Pathology Flashcards
what do you describe in a post mortem
organ
location
distribution
size
shape
demarcation
contour
texture
smell
how would you describe location in a post mortem
which organ
which lobe/part
aspect (dorsal, ventral, medial ect. esspecially important for intestine- changes differential- serosial mucosial)
aaymetric/ symetric
how would ypu discribe distribution of a leasion in a post mortem
diffuse (genrelised)- whole organ
lobular/ regionally diffuse- one lobe
focal/ localized- one discrete spot
genrelised multifocal- multiple discrete spots
localised multifocal- multiple discrete spots in one specific loction
zonal
why is distribution important
it can tell whether a tumour is primary or secondary (e.g a secondaey tumour is more licly to be generalised multifocal as it preads through the bloodstream
demarcation
Clearly demarcated versus blendswith surrounding tissue
contour
Flat versus raised versusdepressed
what could a red colour in a post mortem indicate
Dark red, red-black, pink
Blood – hyperaemia, congestion, haemorrhage, erythrocyte lysis, haemoglobin imbibition
what could a red/black colour in a post mortem indicate
Haemorrhage and necrosis (acute) (often go hand in hand)
what could a yellow colour in a post mortem indicate
icterus
what could a blue/green/black colour in a post mortem indicate
psuedomelanosis (post mortem change)
what could a brown/black colour in a post mortem indicate
melanosis/melanoma (
what could a white/grey/cream colour in a post mortem indicate
necrosis, fibrosis (chronic)
what could texture tell you in a post mortem
firm- firm intervertibral disks can indicate intervertabrale disk disease
friable- can indicate that tisues are breaking down ( could be pathology (amyloidosis) or post mortem effect)
gritty- can result in bloodstream when euthanised with barbituates
incidentaloma
pathology that did not lead to the death of the animal
what are the components of the morphological diagnosis
distribution
severity
timescale
organ or tissue
patholgical process
(a summary of the lesions and an interpreta- tion of the likely disease processes)
what would be the morphological diagnosis of very large mesenteric lymphnoes form a dead foal that are puss filled when insised
Diffuse, severe, suppurative, mesenteric lymphadenitis
supprative indicates bacteria- Rhodococcus equi
what would be the morphological diagnosis of generalised dark lung lesions in a pig
multifocal, mild, suppurative pneumonia
Mycoplasma
hyopneumoniae
what would be the morphological diagnosis of multiple spread out, fiberous lesions on a cow liver
Multifocal, chronic, marked, pyogranulomatous hepatitis
microbaterium bovus- tb
pathognomonic
specifically characteristic or indicative of a particular disease or condition.
what should be taken into acount when deciding whether an animal died suddenly or not
History-Is it sudden or unexpected, both or neither?
Any previous history of illness?
Suspicion of neglect?
Gross examination- Body condition, fat stores (serious atrophy of fat) and muscle coverage
Food in stomach?
Injuries, haemorrhage
Histopathology- Serous atrophy of fat
Heart
what are the body sytems can cause sudden death
nervous
cardiovascular- gdv in gastrointestinal system effects this
respiritory
describe how the nervous system can be involved in sudden death
pathology can be very subtle or very obvious
neurogenic shock
Trauma
Hypoxia/anoxia
Oedema
Toxins
Seizures
neurogenic shock
any factor that stimulates parasympathetic activity or inhibits sympathetic activity of vascular smooth muscle and can cause neurogenic shock, this reults in widespread and massive vasodilation
How can the autonomic system be damaged?
Trauma
Hypoxia/anoxia
Oedema
Toxins
Seizures- can be pathologically subtle. cardiac arythmia, respiritory disfunction
what would we examine the brain for in a case of sudden death to prove it was the cause
History- Trauma, Seizures
Gross examination- Skull fractures, Areas of haemorrhage in the brain
Microscopic examination- Unless obvious trauma/haemorrhage, is difficult
Hypoxic events and seizures will typically leave no trace visible by histopathology- Diagnosis of exclusion
any trauma abouve t5 can result in
damage to the autonomic nervous system and sudden death
the adrenal medulla is primerally responsible fro producing
catecholamines- tese hormones are released into the body in response to physical or emotional stress. The main types of catecholamines are dopamine, norepinephrine, and epinephrine. Epinephrine is also known as adrenaline.
agonal changes
Agonal changes take place immediately before death and are due to circulatory failure. The most common change of which to beware in this category is hypostatic congestion of the lower lung, which may be confused with pneu- monia.
what bosy system is the most common cause of sudden death in dogs and cats
cardiovascular
Pathophysiology of death due to cardiac failure
Structural
Electrical
Ischaemic
Pathophysiology of death due to vascular failure
Ischaemic
Shock
causes of sudden death due to the cardio vascular system
Pathophysiology of death due to cardiac failure-Structural
Electrical- diagnosis of exclusion
Ischaemic - a condition in which the blood flow (and thus oxygen) is restricted or reduced in a part of the body- may see hypoxia if animal lives for 6 hours after
Pathophysiology of death due to vascular failure- Ischaemic- infarction, thrombus,
Shock
describe the pathology of vessels when investigating sudden death due to the cardiovasular system
Pathology of the vessels- Evidence of haemorrhage?
Evidence of disease of organs involved in fluid and electrolyte haemostasis? -GI, Urinary, Endocrine (addisons disease?)
Open pulmonary arteries and aortic bifurcation
Take sections of kidney for histeopath - End arteries therefore good place to look for small thromboemboli
waht would be examined in the heart when inspecting sudden death cuased by the cardiovascular system
Pericardial effusion?
Weight
Measurements
Gross lesions
Sections for histopathology
Sudden death - respiratory
“Respiratory failure occurs when there is inadequate exchange of O2and CO2to meet the needs of metabolism, which leads to hypoxaemia, with or without hypercarbia”
Respiratory failure can be divided into:
Type I respiratory failure, in which processes that impair oxygen transfer in the lung cause hypoxaemia (acute or hypoxaemic respiratory failure)
Type II respiratory failure, in which inadequate ventilation leads to retention of CO2 , with hypercarbia and hypoxaemia
‘Mixed’ respiratory failure, in which there is a combination of type I and type II respiratory failure (acute-on-chronic respiratory failure).
The most common cause of death due to respiratory failure in dogs is reported to be accidental asphyxiation due to choking on food material
Acute respiratory distress syndrome- Secondary to inflammation/infections elsewhere in the body, Often pancreatitis, Sudden but likely expected and/or dog already hospitalised
BOAS- Brachycephalic Obstructive Airway Syndrome
Heat stroke
Peri-anaesthetic
Type I respiratory failure
in which processes that impair oxygen transfer in the lung cause hypoxaemia (acute or hypoxaemic respiratory failure)
low presure- high altitude
hypoventilation under anasthesia
ventilation diffusion imparment
perfuion mismathc
right to left shunt
Type II respiratory failure
in which inadequate ventilation leads to retention of CO2 , with hypercarbia and hypoxaemia
abnomalities of cantral respiritory drive
neuromuscular dysfunction
abnormalities of chest wall
abnormalities of airway
abnormalities of lungs
‘Mixed’ respiratory failure
in which there is a combination of type I and type II respiratory failure (acute-on-chronic respiratory failure).
BOAS
“Brachycephalic obstructive airway syndrome (BOAS) is a term used to describe a raft of upper respiratory tract problems that occur in brachycephalic breeds. Clinical signs vary in severity and include stertor (noise), stridor ( increased effort), exercise intolerance, collapse and cyanosis (blue colouring). Affected dogs are also predisposed to syncope, gastro-oesophageal reflux, vomiting and regurgitation.”
pulmonary haemorrhage in horses
cause eof repiritory sudden death
Pulmonary haemorrhage is a common clinical condition and PMfindingin equine athletes.
Exercise-associated fatal pulmonary haemorrhage (EAFPH)-
describe fatal pulmonary haemorrhages in racehorses
Fatal pulmonary haemorrhage is one of the most frequent causes of sudden death in racehorses, and such lethal pulmonary bleeding has been reported long before the acronym EAFPH was coined
The occurrence of acute cardiac failure or spastic contraction of pulmonary postcapillary sphincters have been listed as possible pathogenetic mechanisms for the occurrence of EAFPH, but this has not been proven
Exercise-induced pulmonary haemorrhage (EIPH)-
The term was first used in1981 to describe epistaxis of pulmonary origin, especially after exercise.
EIPH is believed to be an important cause of reduced athletic performance, especially in cases with severe bleeding, however its role in sudden death is complicated
Exercise-associated fatal pulmonary haemorrhage (EAFPH)
A term first reported in 2015, used to describe fatal pulmonary haemorrhages in racehorses
Fatal pulmonary haemorrhage is one of the most frequent causes of sudden death in racehorses, and such lethal pulmonary bleeding has been reported long before the acronym EAFPH was coined
The occurrence of acute cardiac failure or spastic contraction of pulmonary postcapillary sphincters have been listed as possible pathogenetic mechanisms for the occurrence of EAFPH, but this has not been proven
post mortem findings will show widespread blue/black discolouration on the lungs distinguishabke by its spread from the more schronic case seen in EIPH
Exercise-induced pulmonary haemorrhage (EIPH)
The term was first used in1981 to describe epistaxis of pulmonary origin, especially after exercise.
EIPH is believed to be an important cause of reduced athletic performance, especially in cases with severe bleeding, however its role in sudden death is complicated
post mortem findings of the lungs in which this occurs may show blue black areas on the doral aspect of the lungs
will have haemociderophages- macrophages that have taken up blood
suggests chronic condition
what is the aeitological agent of haemorrhagic pneumonia in kenneled dogs
Aetiology = Streptococcus equi subsp. Zooepidemicus
haemorrhagic pneumonia in kenneled dogs
Aetiology = Streptococcus equi subsp. Zooepidemicus
Pathogenesis is unclear however stress and concurrent viral infections may play a role
Typical gross finding is that of a thoracic cavity filled with blood and histopathology of the lungs reveals a necrotizing suppurative bronchopneumonia: suprative- lots of neutrophils, necrotising- necrosis of the alveolar walls
appart from Streptococcus equi subsp. Zooepidemicus, what may cause haemorrhagic pneumonia in dogs
Extraintestinal E. coli will also cause a haemorrhagic pneumonia
what two aeitiological agents may cause haemorrahgic pneumonia in dogs
Extraintestinal E. coli
Streptococcus equi subsp. Zooepidemicus
what things should you consider in Sudden death in ruminants
Several factors make the definition of ‘sudden death’ in farm animals problematic.
The most commonly accepted definition is death that occurs since the last inspection (ie, within 12 to 24 hours).
However, it can be challenging for the farmer to detect early clinical signs of disease in farm animals due to- Extensive husbandry
Infrequent inspection
Difficulty in recognition of individual animals difficult.
Animals often scavenged
Trauma- Dog attack
Electrocution- Often asked to pronounce on suspected lightning strike due to its common inclusion in insurance policies.
Circumstantial evidence, such as nearby trees, water or wire fencing, plus knowledge of a recent storm, is vital to diagnosis.
Multiple animals dead by metal railings if due to faulty electrical equipment
Death is usually instantaneous with few distinguishing features
There may be singe marks on the skin, a rapid onset and disappearance of rigor mortis and rapid decomposition of the carcase with distension of the rumen.
only consistant finding in electrocution cases is quick onset of rigor mortis in combination with it quickly fading
Acute infection- Anthrax
Clostridial diseases
Anthrax
Anthrax is a cause of outbreaks of sudden death, particularly in ruminants, however can affect other grazing animals and humans.
Clinical signs in animals that do not die suddenly include high fever, tachycardia and tachypnoea, and congested and terminally cyanotic mucosae with haemorrhage.
Animals that survive longer than a day may have dysentery, abortion, oedematous swellings of the perineum, throat and abdominal wall, and blood-stained milk.
The characteristic sign in pigs is swelling of the pharyngeal region and neck.
Anthrax is notifiable and zoonotic, so if you suspect it you must call APHA
Triage all callsbefore accepting dead ruminants for PM
Due to the high fever, animals decompose rapidly resulting in typical saw-horse bloated appearance
DO NOT open up the animal, it is spread by spores which can become aerosolised
If the animal has been accidentally opened up, immediate gross post mortem findings include blood filled cavities and marked splenomegaly- not many other things in cattle cause this
often in sudden death the spleen contracts due to shock unless barbituates are involved
Diagnosed in field by taking a blood smear from the ear
Rod-shaped bacteria with capsule
Sudden death in ruminants – clostridia
Whist the GIT is not an organ that can kill you quickly, clostridial organisms found in the GIT can under the right circumstances produce toxins that affect predominantly affect the CVS and neurological systems
Pathophysiology:
Clostridium perfringens is a gram positive anaerobic bacillus
C. perfringens types B and D produce epsilon toxin (ETX) resulting in enterotoxemia
ETX is a pore forming toxin with particular affinity for vascular endothelial cells
This changes the permeability of the small and large intestine
The other target organs of the toxin include the kidneys, lungs and brain
toxins cause disease
Clostridium perfringens epsilon toxin: the third most potent bacterial toxin known
C. perfringens is a commensal however certain situations can result in overgrowth
Typically fat lambs or animals that have broken into feed containers or gone onto lush grazing
Waning of maternal immunity
Antibiotic use in rodents – C. difficile.
watery bloody diherea
fluid filled intestins
toxins go to kidney lung and brain
effect cardiovascular and neurological systems
Gross pathology
Fluid accumulation, mucosal haemorrhaging and haemorrhagic content in the small intestine and large intestine- may occur in pericardial sack
Also seen in all species with clostridial enteritis
Pigs may have emphysematous wall
Widespread haemorrhages
Hydropericardium, hydrothorax and pulmonary oedema
“Pulpy” (soft) kidneys
Brain
General brain swelling leads to flattening of the gyri and cerebellar coning in some cases. cerebella coning- The herniation of the cerebellar tonsils through the forament magnum
Symmetrical focal malacia (softening) - perhaps due to glutamate as this part of brain is heaily relinant on it and it is an exitable chemicale
looks brown grey
Diagnosis- Culture of intestinal content not useful as is a commensal
Ileal content- Look for the toxin, often breaks down before it is found though ( it is “Labile”)
Glucosuria is typical but not pathognomonic as indicates systemic toxaemia
Histopathology- Brain, white matter
protein-rich perivascular oedema (microangiopathy)- this is due to the pore forming toxin
malacia
softening
Sudden death in pigs – salt poisoning
happens when pigs engorge with water- maybe sue to not having acces for a while
show muscle fasciculation, blindness, seizures or were down, non-responsive.
No significant gross pathological lesions are evident in the brain
eosinophils may be seen
ALBUMIN
protien
Produced in the liver at a constant rate
Major contributor to plasma oncotic pressure
Carries ion molecules (calcium, magnesium)
oncotic pressure
Oncotic pressure, or colloid osmotic-pressure, is a form of osmotic pressure induced by the proteins, notably albumin, in a blood vessel’s plasma (blood/liquid) that causes a pull on fluid back into the capillary.
protiens contribute to this
GLOBULINS
Subdivided into: Alpha, beta, and gamma globulins
Includes: Inflammatory cytokines, immunoglobulins
Produced by many different cell types. Major contributors:
Liver: Acute phase proteins (increased during inflammation), coagulation proteins (clotting factors, anticoagulants)
Lymphocytes: Immunoglobulins
Hyperproteinaemia- High albumin
dehydration
Hyperproteinaemia- High globulins
dehydration, inflammation, neoplasia
Neoplasia refers to lymphoma & myeloma, which produce monoclonal immunoglobulins
Detection of monoclonal immunoglobulins can be done via serum protein electrophoresis
Hypoproteinaemia
Hypoproteinaemia can be categorised as follows:
Selective hypoproteinaemia
Hypoalbuminaemia
Hypoglobulinaemia
Total proteins can be WRI
Panhypoproteinaemia
Both albumin and globulins are below WRI
Selective hypoproteinaemia
Hypoalbuminaemia
Hypoglobulinaemia
Total proteins can be WRI (reference interval) - total protien is normal
albumin and globulins should be looked at seperatly
Panhypoproteinaemia
Both albumin and globulins are below WRI (reference interval
When both albumin and globulin are lost together.
Two main categories:
Protein-losing enteropathy (common)- Lymphoma
IBD
Lymphangiectasia
Parasitism
Protein-losing dermatopathy (rare → severe burns)-
Selective hypoproteinaemia: Hypoalbuminaemia
Can be caused by:
Reduced production
Liver disease
Inflammation- negative acute phase protien so a drop in albumin is a normal response to inflamation
Losses:
Renal disease → protein-losing nephropathy (PLN)- kidneys shouldnt loose protien, damage to the glomerulus can cause this to happen. it tend to be albumin that is lossed first due to it being more passible
Movement from blood into body cavitary effusion
Selective hypoproteinaemia: Hypoglobulinaemia
Rare! Encompasses so many proteins, unusual to lose so much of one that it has a significant impact on total globulins.
Check dehydration is not masking concurrent hypoalbuminaemia
Consider double checking with a reference laboratory
Main differential: Immunodeficiency resulting in severe reductions immunoglobulin production (e.g. Severe combined immunodeficiency)
what are enzymes used to check for
Generally used to check for cellular injury.
Commonly measured enzymes can be broadly categorised into those from:
Liver
Biliary tract
Muscle
Pancreas
Some enzymes are produced by multiple tissues → need to look at panels to work out which tissue is affected. ast is prosuced byt the liver and the muscle
There can be multiple different versions of one enzyme: “isoenzyme”
isoenzyme
when there are multiple different versions of one enzyme
Interpreting enzyme changes- mild
1-2 x upper end of reference interval
Exceptions given to when the half life is very small for that species, and for specific enzymes such as GGT.
Interpreting enzyme changes- moderate
2-4 x upper end of reference interval
Exceptions given to when the half life is very small for that species, and for specific enzymes such as GGT.
interpreting enzyme changes- marked
5+ x upper end of reference interval
Exceptions given to when the half life is very small for that species, and for specific enzymes such as GGT.
SDH
(sorbitol dehydrogenase)
not very stable
GLDH better option
produced in liver
Generally only used in large animals
ALT
produced in Liver, muscle
more sensitive marer for liver than muscle
Not useful in large animals
Cat ALT has much shorter half life compared to dogs → smaller elevations are more clinically significant
GLDH
Liver marker
More stable than SDH
AST
equal markers for Liver, muscle
long half life
ALP
Biliary (within the liver), bone, intestines, steroid- diffrent isoenzyme
Steroid isoenzyme only in dogs- important for cushings
growing animals produce more alp due to bone growth but this can also happen with bone cancer
colicing horses have increse
only specilised equipmetn can tell siffrence between isoenzymes
Cat ALP has much shorter half life compared to dogs → smaller elevations are more clinically significant
Canine steroid ALP isoenzyme is elevated with both drugs (corticosteroids, phenobarbital), chronic stress, and hyperadrenocorticism
GGT
very specifically Biliary
Small increases significant- mild, moderate and mared scale less usefull here
Colostrum is high in GGT → increases in calves
Can be used to check for passive transfer
Also elevated in foals but not due to colostrum
in horses:
Increase in GGT associated with chronic biliary stasis
Good indicator of chronic liver disease
Persistent increases above 400 IU/L associated with poorer prognosis
good sensitivity, low specificity in horses
Other hepatobiliary markers
Bile acids
Bilirubin
Cholesterol
Albumin
Glucose
Coagulation factors
Bile acid cycle:
Produced by hepatocytes and excreted into the bile
Degradation occurs in the gut, then the transformed bile acids are reabsorbed
Transported to hepatocytes via the hepatic portal vein
Hepatocytes uptake the transformed bile acids for reprocessing
Bile acid stimulation test
Tests the ability of the liver to re-uptake bile acids from the portal vein.
Patient is sampled after being starved for 8 hrs so no more bile acids are released, then resampled after being fed.
Increases are supportive of either:
Reduced hepatocellular function (NB: does not necessarily indicate failure)
Portosystemic shunt (blood bypasses liver)
Cholestasis (don’t bother running this test if bilirubin is increased!) → bile acids are usually high before and after stimulation testing
Only measure single BA assay in horses
BA stimulation test not applicable for continual grazers
Will increase with prolonged fasting
Highly specific for liver disease
Good prognostic indicator
Normal <15mmol/l
Persistent increase >50mmol/l = Poor prognosis
Bilirubin
Two main types of bilirubin:
Unconjugated bilirubin
Made during breakdown of heme (from dead RBCs)
Insoluble; transported bound to albumin
Conjugated bilirubin → negligible levels in health
Has been processed by the liver and conjugated with glucuronide
Water soluble; majority is transported free
Delta bilirubin = conjugated bilirubin that is bound to albumin (tiny amount)
Analysers can give three different types of bilirubin measurement:
Total bilirubin- Total bilirubin = direct bilirubin + indirect bilirubin
Direct bilirubin → measured value- Total conjugated bilirubin
Indirect bilirubin → calculated value (total bilirubin - direct bilirubin)- Total unconjugated bilirubin
Most analysers give only total bilirubin
Causes of bilirubin increases can generally be broken down into:
Pre-hepatic = excessive breakdown of heme or inhibition of bilirubin uptake by hepatocytes
Haemolysis, fasting (horses, cattle)
Unconjugated bilirubin increases, can eventually lead to both being increased
Hepatic = reduced ability to conjugate bilirubin
Toxic insult, Leptospirosis (dogs, cattle)
Both conjugated and unconjugated fractions increased
Post-hepatic
Gallstones, mucocoele, pancreatitis (cats)
Unconjugated bilirubin increases first, then both increase as the system “backs up”
Pre-hepatic bilirubin increase
excessive breakdown of heme or inhibition of bilirubin uptake by hepatocytes
Haemolysis, fasting (horses, cattle)- cows and horses get a normal ncrease of this
Unconjugated bilirubin increases, can eventually lead to both being increased
Hepatic billirubin increase
reduced ability to conjugate bilirubin- stays in liver cells
Toxic insult, Leptospirosis (dogs, cattle)
Both conjugated and unconjugated fractions increased
Post-hepatic billirubin inxrease
problem with flow of bile
Gallstones, mucocoele, pancreatitis (cats)
Unconjugated bilirubin increases first, then both increase as the system “backs up”
Cholesterol
Produced in the liver but other sources include:
Uptake from food via lymphatics- Usually triglycerides increase also
Release from adipose tissue during negative energy balance- Usually triglycerides increase also
Increases can be particularly high if animal is overweight
Present within the bile in high concentrations
cholesterol Increases due to:
Cholestasis- Look for concurrent increases in bilirubin, GGT, ALP
Starvation/anorexia- Usually triglycerides increase also
Recent meal- Usually triglycerides increase also
Nephrotic syndrome- hepatocytes stimulated to make more cholesterol. not common
choleserol Decreases due to:
Reduced intestinal absorption
GI disease, hypoadrenocorticism
decrease in albumin and glucose
If the liver is end-stage, then these can drop due to reduced production/storage.
causes of hypoglycaemia include:
Diabetic ketoacidosis
Starvation (puppies, working dogs)
Insulinoma → pancreatic neoplasm which produces insulin
Artefact → use fluoride oxalate tube
Coagulation factors
Liver synthesizes coagulation factors
Liver failure → prolonged coagulation times
Muscular enzymes
CK
AST
ALT
CK
Muscle marker
Short half life
CK vs AST timeline
Half life of CK much shorter than AST.
Ratios of these enzymes can vary depending on time point.
NB: Owner handling and recent exercise
Pancreas: Pancreatic lipase
Used to diagnose pancreatitis but can also go up when GFR is reduced.
LIPASE IS ALSO EXCRETED BY THE KIDNEYS, so kidney damage can also effect this
Measured by a multitude of methods:
DGGR lipase- Not fully sensitive or specific, but good screening test
Can increase in dogs with hyperadrenocorticism
Drugs can increase DGGR lipase: corticosteroids, heparin
Specific pancreatic lipase immunoreactivity (cPLI, fPLI)- More specific and sensitive than DGGR lipase
SNAP pancreatic lipase immunoreactivity - Qualitative test for a quick “yes” or “no”
As a general rule, positive = positive, negative = maybe
Pancreas: amylase
Used to diagnose pancreatitis but can also go up when GFR is reduced.
Poorly sensitive in cats
lipase is generally better
Pancreas: TLI
Usually used to diagnose EPI (exocrine pancreatic insuficiency) (whereby levels are decreased)
Can go up with pancreatitis or with incomplete starvation
nonspecific for pancreatitis
tissue structure of renal pysiology
Glomerulus
Renal tubules- Proximal tubule
Loop of Henlé
Distal convoluted tubule
Collecting duct
Renal physiology: Glomerulus
Electrolytes filtered out.
Proteins should remain in blood.- Small amount of protein present in canine urine
Location of juxtaglomerular apparatus (RAAS)
Renal physiology: Proximal tubule
Resorb most electrolytes
Activate Vitamin D- calceum homeostasus
Renal physiology: Loop of Henlé
Absorption of H2O in the descending limb.
Absorption of NaCl in the ascending limb.
Creates the medullary concentration gradient required to concentrate urine in the collecting duct.
Renal physiology: Distal convoluted tubule & collecting duct
Small amounts of electrolytes resorbed in DCT
Collecting duct reabsorbs H2O → concentrated urine
Glomerular filtration rate
Speed at which fluid is filtered out of the blood into the Bowman’s capsule
Controlled by:
Hydrostatic pressure- The rate at which blood enters the glomerular capillaries
The rate at which blood leaves the glomerular capillaries
The rate at which filtered fluid moves through the renal tubules
Oncotic pressure- Amount of albumin within the peripheral blood
Alterations in hydrostatic pressure - renal in-flow
Increased in-flow: High cardiac output
High blood pressure → idiopathic, hyperthyroidism
Decreased in-flow: Low cardiac output → heart failure, shock
Water loss (decreased hydrostatic pressure) → dehydration
less inflow means thing sflow through slower and filtration slows down
Compensation occurs via dilation/constriction of efferent vessel
Compensation limited
Reduced flow through tubules:
Injury to glomerulus
Injury to tubules
Urinary obstruction → urolithiasis
Increased flow through tubules
Excretion of osmoactive substances
Glucose → diabetes
Mannitol → therapy
Diuretics
Loss of medullary tonicity - Psychogenic polydipsia (drinking an exessive amount) or diabetes insipidus → loss of electrolytes = “medullary washout”
Liver failure → loss of urea production
Renal biomarkers
Urea
Creatinine
SDMA
Others used in literature but not routinely in clinical practice:
Clearance of inulin or iohexol
Neutrophil gelatinase-associated lipocalin (NGAL)
Retinol binding protein
Creatinine
Released by muscles at a constant rate
Excreted entirely by kidneys - no reuptake
Concentration in blood dependent on:
Production- Higher with heavy muscle mass → greyhounds
Lower with muscle wasting → young and elderly patients
Rate of excretion (i.e. GFR)- main reason to look at creatinine
kidneys are resiliat- Requires damage to 75% of nephrons for increase so not sensative
Urea
Produced by the liver during protein metabolism
Excreted by the kidneys - small amount of reuptake
Provides the concentration gradient for loop of Henle
raw diet may increase abouve reference interval
GI bleeding may cause it but must be severe and is usually not main reason
Concentration dependent on:
Production- Reduced with liver failure
Increased with high protein diet
Increased with GI bleeding —> Controversy
Rate of excretion (i.e. GFR)- Requires damage to 75% of nephrons
SDMA (symmetric dimethylarginine)
not dependent on muscle mass like creatanine
Released by all nucleated cells at a constant rate
Excreted entirely by kidneys - no reuptake
Concentration in blood dependent on:
Rate of excretion (i.e. GFR)
Requires damage to 25% of nephrons unlike urea
NB: Greyhounds have naturally high SDMA
Other experimental markers for kidneys
Clearance of inulin or iohexol- Used routinely in human medicine
Neutrophil gelatinase-associated lipocalin (NGAL)- Released by injured renal tissues
Measured as urinary NGAL:Creatinine ratio
High sensitivity, specificity unclear (also released by neutrophils)
Retinol binding protein (RBP)- Made by liver and freely filtered
Measured as urinary RBP:Creatinine ratio
Azotaemia
Increase in urea, creatinine, and/or SDMA
Classification:
Pre-renal → renal blood supply, increased urea production
Renal → problem with the kidney itself
Post-renal → obstruction of urine outflow
Azotaemia- Pre-renal
how good is renal blood supply, increased urea production
diet?
Azotaemia- renal
problem with the kidney itself
Azotaemia- Post-renal
obstruction of urine outflow
Azotaemia - urea and creatinine
Require a loss of 75% of functioning nephrons before increases are detected.
For every doubling above reference interval, GFR reduces by 50%.
IRIS scheme
Used to evaluate the degree of renal injury via staging
Useful in guiding therapy
Schemes available for both acute and chronic renal disease
Acute Kidney Iinflation vs Chronic Kidney Disease
Step 1: Signalment
Age
Breed
Step 2: History
Onset of PUPD or anuria
Collapse?
Known toxin ingestion
Skin lesions (Alabama rot)
Step 3: Biochemistry / CBC
Severity of the azotaemia
Multiple organs affected
Anaemia
mild to moderate azitaemia- chronic
marked- acute
other organs effected? liver effected could indicate toxin
end stage disease can lead to non regenerative aneamia
Uraemia
build up of ureamic acids- bosy goes into acidosis
Clinical syndrome:
Lethargy/depression
Mucosal ulceration → oral, gastric
Vomiting/diarrhoea
Respiratory signs → uraemic pneumonitis, metastatic calcification
Hypertension → can lead to hypertrophic cardiomyopathy
Hypokalaemic myopathy (cats) → plantigrade stance, cervical ventroflexion
Hyperkalaemic bradycardia → acute kidney injury & urinary obstruction
Anaemia → non-regenerative
renl problems- Electrolyte disturbances
Sodium- Drops
Chloride- Usually as per sodium, but can increase independently depending on the cause of the injury
E.g. Fanconi’s syndrome
Potassium- AKI or urinary obstruction: Increases in all species → can be severe
CKD:
Dogs & horses: Increases
Cats: Decreases → may need supplementation
Calcium- Variable
AKI: Increases
CKD: Increases at first, then drops during end-stage failure
Urinary obstruction: Drops - but we don’t know why!
Phosphate- Increases, cant be excreted
Magnesium- Increases, cnat be excreted
Renal handling of major electrolytes
Aim is to conserve water by retaining sodium
Creates a concentration gradient to reabsorb H2O
Chloride generally moves with sodium → NaCl
Potassium secreted in exchange for sodium
Sodium as an electrolyte
Most abundant electrolyte
Important factor in maintaining tonicity/osmotic pressure
Increases due to:
Free water loss → diabetes insipidus
Water deprivation
Too much- Salt poisoning
Hyperaldosteronism- aldosterone is th ehormone that encorages the swithcing of sodium and potassium n the renal tubules
Decreases due to losses from:
GI tract → diarrhoea, vomiting
Kidneys → medullary washout, diabetes mellitus (increases gfr) , hypoadrenocorticism (less aldosterone)
Cavitary effusions
Perspiration → horses
electrolytes- Chloride
Second most abundant electrolyte
Increases and decreases are usually in association with sodium
Instances where you lose more chloride that sodium:
Vomiting
Pyloric outflow obstruction → GDV, LDA, foreign body
Instances where you lose more sodium than chloride:
Proximal small intestinal diarrhoea → pancreatitis
Renal tubular injury → Fanconi’s syndrome
Hypoadrenocorticism- not enough ardosterone
Corrected chloride
If NaCl is lost or gained, then sodium and chloride should increase or decrease in equal proportions. In order to work out if chloride levels are in proportion with sodium, a corrected chloride can be calculated.
Corrected chloride = (Na / [centre of Na reference interval]) * Cl
If the corrected chloride is WRI, then chloride is proportionate to sodium
electrolytes- Potassium
Important regulator of pH and cell electrochemical gradient- Used by cells to exchange for H+ when blood pH is altered
Exchanged for Na+ to maintain electrochemical gradient- Higher amounts of K+ inside cells vs outside
Decreases are due to:
Alkalosis
Decreased intake → anorexia (very common in horses)
Perspiration → horses
Increases are due to:
Acidosis
Reduced renal excretion → CKD, AKI, urinary obstruction, hypoadrenocorticism
Artefact (common) → haemolysis, delayed serum separation
Acidosis
Blood pH is tightly regulated ~7.4
Drop in blood pH = acidosis → increased H+
alkalosis
Blood pH is tightly regulated ~7.4
Climb in blood pH = alkalosis → decreased H+
metabolic changes in blood ph
acids or bases building up in tissues/blood
respiritory changes in blood ph
affected by ability to exhale CO2
Metabolic acidosis
Occurs when acids start building up in the tissues/blood or when bases are lost
Metabolic acidosis causes:
If you lose Na in excess of Cl (i.e. loss of NaHCO3)
H2CO3 + NaCl → NaHCO3 + HCl ( retention of hydrochloric acid)
NaHCO3 is excreted in:
Pancreatic/biliary secretions → reabsorbed in small intestines in health
Kidneys → reabsorbed again within tubules in health
HCl gets left behind if you have:
SMALL INTESTINAL DIARRHOEA
Specific types of RENAL TUBULAR INJURY (e.g. Fanconi’s Syndrome)
HYPOADRENOCORTICISM (affects ion exchange in kidney)
Metabolic acidosis causes:
If you retain acids → measurable with Anion Gap
Ketones → DIABETES MELLITUS
Lactate → INJURED OR HYPOXIC TISSUES
Uraemic acids → RENAL INJURY
Metabolic alkalosis
Occurs when acid is lost
Metabolic alkalosis causes:
If you lose HCl- VOMITING → gastric secretions high in HCl
TWISTED STOMACH (GDV) or DISPLACED ABOMASUM → HCl secreted into stomach but cannot enter small intestine to be resorbed → “lost” in the stomach
Pyloric outflow obstruction (GASTRIC FOREIGN BODY) → as above
GASTROINTESTINAL STASIS → as above
Respiratory acidosis
Occurs when CO2 is not exhaled sufficiently
CO2 is an acid → decreased exchange → build up of CO2 → acidosis
Respiratory acidosis causes:
Respiratory tract obstruction
Pulmonary fibrosis
Pulmonary thromboembolism
Pulmonary neoplasia
Pneumonia
Anything that reduces O2/CO2 exchange…
Respiratory alkalosis
Occurs when CO2 is exhaled excessively
Respiratory alkalosis causes:
Tachypnoea
CO2 is an acid → increased exhalation → alkalosis
Mixed acid/base disorders
Where you have more than one acid/base disorder occurring concurrently:
Renal failure with vomiting: Renal failure = metabolic acidosis
Vomiting = metabolic alkalosis
Diabetic ketoacidosis and pancreatitis:
Ketoacidosis = metabolic acidosis
Pancreatitis = metabolic acidosis +/- metabolic alkalosis (if there is vomiting)
Septic abdomen (lactic acidosis) and hyperventilation:
Sepsis = metabolic acidosis
Hyperventilation = respiratory alkalosis
Vomiting causing aspiration pneumonia:
Vomiting = metabolic alkalosis
Pneumonia = respiratory acidosis
Potassium - acidosis
Acidosis = excess H+
H+ taken into tissue and exchanged for K+ → rise in blood K+
Potassium - alkalosis
Alkalosis = H+ deficit
H+ taken out tissue and exchanged for K+ → drop in blood K+
balence of calceum and phosphorous
Balanced controlled by PTH and Vitamin D
Vitamin D less important in horses
Excreted by the kidneys and absorbed by the intestines
UV light for vitamin D production not applicable in veterinary species
Dietary intake and balance important, especially in horses
Total calcium
total calcium bound to albumin and uraemic acids
Total can increase or decrease with fluctuations in these negatively charged molecules → especially albumin
low albumin should cause low calcium- if not check unbounded calcium
Free (aka ionised) calcium
unbound calcium
Levels very tightly controlled by PTH, vitamin D and calcitonin
differentials of Hypercalcaemia-
HARD IONS G
Hyperparathyroidism → decreased excretion and increased bone resorption
Addison’s disease → decreased excretion
Renal disease → decreased excretion
D-hypervitaminosis → psoriasis cream, rodenticide poisoning
Idiopathic → most common cause in cats
Osteolytic → osteosarcoma
Neoplastic → PTHrp
Spurious → artefact, analyser error
Granulomatous disease → macrophages produce vitamin D
differentials of hypocalcaemia
Nutritional- Insufficient dietary intake
Excessive phosphorus intake
Hypomagnesaemia
Renal- Chronic: insufficient Vitamin D production
Not relevant in horses
Acute: reduced tubular reabsorption
Urinary tract obstruction: unknown
Pregnancy/lactation
Pancreatic pathology- EPI: reduced vit D absorption
Acute pancreatitis: unknown
Drugs/toxins- Ethylene glycol
Furosemide
Tissue injury- Massive necrosis (e.g. in tumours)
Rhabdomyolysis, polysaccharide storage myopathy
Rumen overload: unknown
phosphorus increase
Decreased excretion- Renal injury (but not in horses!)
Release from injured cells- Massive necrosis (e.g. in tumours)
Rhabdomyolysis, polysaccharide storage myopathy
Artefact with haemolysis or sample storage
Excessive vitamin D
decreased phosphorous
Increased excretion- Hyperparathyroidism
Fanconi’s syndrome (dogs)
Renal failure in horses
Reduced intake
Hypovitaminosis D
changes in Magnesium level
Only rarely measured in practice.
Has bound and unbound fractions like calcium.
Most important aberrations:
Increases with renal disease (reduced excretion)
Decreases due to dietary deficiencies (aka staggers)
Limitations of population-based reference intervals
Some analytes are very specific to that individual- Intra-individual variation is small but group variation is wide
E.g. creatinine
Analyser precision and accuracy may not be perfect
All analysers should be precise around decision thresholds
A small degree of inaccuracy allowed → varies between analyte
Analysers should be checked regularly → QC very important!
Not all assays are perfectly linear
Once a threshold is reached, higher or lower measurements can become less accurate and precise
Sample haemolysis/lipaemia/icterus can interfere with some assays
Seasonal/diurnal variation- Reference intervals may vary depending on the season or time of day
Can be very important when monitoring medication
Variations with breed and age- Greyhounds have many breed-specific variations
Some analytes change as patients age
Use of generic intervals for exotic species- “Reptile” intervals for lizards and snakes
“Avian” intervals for chickens and parrots
Seasonal ACTH variations in horses
ACTH levels used to help diagnose PPID
ACTH levels peak naturally in Autumn
Different reference ranges required in Autumn
canine t4 varies with
age
sensitivity
the ability of a test to detect sick patients
the ability of a test to exclude a disease when you get a negative result
specificity
the ability of a test to exclude a disease when you get a negative result
when you get a positive reusult you know that the disese is present
Decision thresholds
Some diseases use decision thresholds to rule in/out disease. Very common when diagnosing endocrine disease.
Examples:
Basal cortisol → hypoadrenocorticism
Total T4 → hypothyroidism/hyperthyroidism
ACTH → PPID in horses
IGF-1 → acromegaly in cats
Fructosamine → diabetes mellitus
Can vary depending on severity of the illness being diagnose-
Infectious disease assays usually very sensitive, but may be a trade off for low specificity
Screening tests often less specific
Confirmatory tests often highly specific
ROC curve analysis most common method- Enables selection of cut-off with highest sensitivity and specificity
checklist for trustworthy results
Is my analyser QC and calibration up to date?
Do I know the grey zone for the analyte?
Electrolytes have very small grey zone
Hormones typically have ~20% variability in assay precision
How reliable is my decision threshold?
Check recent papers or textbooks for sensitivity and specificities
Is the sample haemolysed/lipaemic/icteric?- Check reagent inserts to work out if that analyte is affected
Has my sample been taken/handled properly?- Artefacts can occur if not stored properly, Serum should be separated/spun soon after collection, Gel in serum tubes can interfere with some tests e.g. progesterone
Is this test fully sensitive/specific?- Especially important with positive/negative results
Sensitivity and specificity highly important
Consider further tests if:
Result does not fit clinical picture
E.g. FIV positive antibody test in a young indoor cat
Sensitivity or specificity are not sufficient for a confident diagnosis
E.g. Patient tests positive highly sensitive but poorly specific test
Quantitative result required for confirmation or monitoring purposes
E.g. SNAP cPLI/fPLI tests vs quantitative lipase measurement
Summarise the differences in reasons for performing a post mortem on a farm animal compared to a small domestic animal (dog/cat)
Farm animal:
mostly herd health and disease control reasons: can do a thorough search for all kinds of disease that is just not possible on live animals
domestic animals:
in cases of sudden, uneplained death.
to confirm/refine a clinical diagnosis, to obtain samples for further tests (microbial culture, histopathology), to assess the effect of treatment(s), to collect evidence in forensic cases, or to prevent further illnesses and deaths within in-contact animals (for example, within litters of young puppies or kittens).
List the potential zoonotic pathogens that pose a risk to the pathologist when performing a post mortem on a farm animal
E.coli VTEC 0175
anthrax
TB
Camplyobateriosis
Avian influenza
salmonella
cryptosporisiosis
leptosporosis
orf
ovine chlamysiosis
psittacosis
q fever
ring worm
zoonotic diphtheria
agonal changes caused by barbituate
The spleen is particularly susceptible to extreme congestion relating to barbiturate euthanasia
Crystal deposition on the endocardium is another common barbiturate associated change.
which post mortem changes can help with assessing time of death
rigor mortis, livor mortis, and algor mortis
Algor Mortis- the cooling of the body after death
Livor Mortis
The purple-red discoloration of the soft tissues due to postmortem gravity-dependent pooling of blood is livor mortis. Livor mortis may be observed either externally in the skin and mucous membranes or internally in the abdominal or thoracic viscera, most notably the lung, and typically develops within 30 minutes to 2 hours after death in humans.22 Livor mortis must be distinguished from hemorrhage. In livor mortis, the pooling of blood is entirely within dilated vascular channels, whereas hemorrhage is the escape of blood from the blood vessels and into the connective tissues or internal or external spaces. Therefore, hemorrhage within the soft tissues will not blanch when subjected to digital pressure. Livor mortis, however, depending on its stage of development may blanch when subjected to digital pressure.
Rigor Mortis
Immediately after death, a series of biochemical reactions occurs within the skeletal and cardiac muscle fibers throughout the body. Specifically, adenosine triphosphate (ATP), the molecular source of energy for muscular contraction, continues to be consumed by the muscle cells, resulting in cross-bridge formation between myosin and actin fibers. However, the regeneration of new ATP ceases upon death. Because ATP is required for the decoupling of actin and myosin fibers and the resultant relaxation of the muscle, relaxation can no longer occur after the limited supply of ATP is exhausted. As a result, the muscle fibers remain in a state of permanent contraction, unable to relax because of the lack of additional ATP.
Algor Mortis-
the cooling of the body after death
Livor Mortis
The purple-red discoloration of the soft tissues due to postmortem gravity-dependent pooling of blood is livor mortis. Livor mortis may be observed either externally in the skin and mucous membranes or internally in the abdominal or thoracic viscera, most notably the lung, and typically develops within 30 minutes to 2 hours after death in humans.22 Livor mortis must be distinguished from hemorrhage. In livor mortis, the pooling of blood is entirely within dilated vascular channels, whereas hemorrhage is the escape of blood from the blood vessels and into the connective tissues or internal or external spaces. Therefore, hemorrhage within the soft tissues will not blanch when subjected to digital pressure. Livor mortis, however, depending on its stage of development may blanch when subjected to digital pressure.
Rigor Mortis
Immediately after death, a series of biochemical reactions occurs within the skeletal and cardiac muscle fibers throughout the body. Specifically, adenosine triphosphate (ATP), the molecular source of energy for muscular contraction, continues to be consumed by the muscle cells, resulting in cross-bridge formation between myosin and actin fibers. However, the regeneration of new ATP ceases upon death. Because ATP is required for the decoupling of actin and myosin fibers and the resultant relaxation of the muscle, relaxation can no longer occur after the limited supply of ATP is exhausted. As a result, the muscle fibers remain in a state of permanent contraction, unable to relax because of the lack of additional ATP.
Summarise the procedure for post mortem examination of zoo animals
Adequate facilities must be available either at the zoo or within a reasonable distance
for the post-mortem examination of all species held at the zoo
Animals that die at the zoo should be examined post-mortem in accordance with
veterinary advice. Where appropriate, samples for diagnosis or health monitoring should
be taken for laboratory examination
Following post-mortem examinations conducted on the zoo premises, carcasses and
organs should be disposed of swiftly and in accordance with the Animals By-Products- if possible carcasses of interesting or importan tspecies should be offered to a recognised scientidic institution
(Enforcement) (England) Regulations 2011
List the potential zoonotic pathogens that pose a risk to the pathologist when performing a post mortem on an avian species
psittacosis
avian influenza
campylobacteriosis
salmonella
toxoplasmosis
west nile virus
List the available fixatives for preserving tissues for histopathology
Immersion fixation involves the use of fixative solutions.
Formaldehyde (10% neutral buffered formalin) is by far the most popular fixative used in histology since it penetrates the tissue well and creates crosslinks without affecting the sample tissue’s antigenicity. While it is relatively slow to fix, it is highly recommended for immunohistochemical techniques
Glutaraldehyde fixes quickly and provides great cytoplasmic and nuclear detail, but it penetrates poorly and deforms the alpha helix structure in proteins. As such, it is good for electron microscopy but not so for immunohistochemical staining.
Paraformaldehyde (PFA) is an effective fixative that reacts with primary amines found in the protein to form crosslinks (“methylene bridges”). PFA works great in stabilizing proteins and preserving morphology, but it fixes very slowly (more than 24 hours for smaller tissues and up to a few weeks for larger tissues) and may mask antigenic sites.
Perfusion fixation can best be described as fixation through blood flow. The fixative is injected into the heart and spreads through the entire body. Since the tissue doesn’t die until it is fixed, you can get a sample with perfect morphology. Unfortunately, the subject dies during the process.
Outline how formalin fixation preserves tissues
Formalin (a solution of formaldehyde in water) preserves proteins and cellular organelles in a stepwise process. It penetrates tissues quickly then binds to lysine, tyrosine, asparagine, tryptophan, histidine, arginine, cysteine, and glutamine in all of the proteins present in a specimen. It is the reaction between formalin and uncharged reactive amino groups that leads to the formation of cross-links.
Describe the risk posed by the use of formalin as a fixative and how this is mitigated
Formalin fixation is not selective, so cross-linking of target proteins with unrelated proteins can reduce immunoreactivity with target-specific antibodies. In addition, cross-linking can lead to significant changes in the three-dimensional conformation of proteins which may also reduce immunoreactivity. Fortunately, antigen retrieval methods, such as heat-based or enzymatic procedures, can reverse the undesirable changes caused by fixation
why would we sample blood from exotic species
Health screening – to prove animal is healthy (pre GA/mixing/transfer)
To uncover subclinical disease- Many exotics v good at hiding clinical signs, Some species unable to do thorough clinical examination eg. Tortoise (unable to palpate)
To make a diagnosis
To confirm a diagnosis
To guide further clinical investigation/next steps- Focussed testing important
To help determine prognosis
To help monitor progress/changes
Because we can??!
what considerations must be made for reference ranges of exotic species
Consider reference ranges very critically:
Different populations- diffrent genders may greatly vary unlike domestic species
Clinical context
Management context
Lifestage/signalment
Care with extrapolation between species
Consider panels offered and if appropriate for exotic species
Often very non specific clinical signs - Prey species so mask clinical signs
Often seeing advanced disease process in these animals due to masking signs- Rapid diagnostics often important
Need to narrow down differential diagnoses
considerations when prepping an exotic species for blood collection
Warm reptiles
Fasting?- Crop emptying/species variation
Post meal effects- Hypoglycaemia risks when starving these animals
Prepare in advance- Consider which parameters are priority
Skin preparation
Clipping/plucking?- minimally as possible
Cleaning- reptiles grimy
Care with spirit/alcohol- cools reptiles
Suitable equipment gotten before animal is anethsitised- Needle/syringe
Microhaematocrit tubes
Small sample tubes
0.3ml tubes/1.1ml tubes
considerations for blood sample collection in exotics
Venipuncture techniques
Appropriate restraint- Manual/chemical
do we wan t a pre-anesthetic sample
Anaesthesia/Sedation/Conscious- Stress of GA vs handling
Other procedures
Safety of isoflurane vs stress
Experience/confidence level of operator- ga better for lessed experience
stress and GA Can impact on bloods (eg pH/electrolytes from GA/CK from conscious handling)
Appropriate anticoagulant
Heparinised syringes- reduces risk of loosing blood form already small sample. rabbits and rodents also hsve very rapid clotting times
EDTA – effective in some species but some birds & reptiles this will lyse red blood cells
Lithium Heparin – usually appropriate anticoagulant, appropriate size, reduces need to take more samples
Lipaemia
Lipemia is a turbidity of the sample caused by accumulation of lipoprotein particles
Changes can be pathological or physiological
May affect analysis/parameters
Lymph dilution
lymps vessel or sinus has been sampled through and so tissue fluid is in sample
some exotics can only have small blodsamples taken from them. what can be done with this?
Blood smear – 1 drop required- Huge amount of information
PCV – can use microhaemtocrit tubes (40-75ul tubes)- Total Solids from spun section, Assessment of buffy coat
Critical care parameters – 0.1-0.5ml blood- Electrolytes, pH, Glucose etc
Use lithium heparin and don’t spin- Can then use for haematology & biochemistry
what can imapct blood samples from exotic species
Anticoagulants- Haemolysis protein, electrolytes, cell counts, enzymes
Fasting- Ferrets, other small mammals – see lower levels
Post meal- Elevations in glucose, total protein, uric acid
Restraint -Elevations in creatinine kinase, AST
Anaesthesia- Changes in electrolytes, creatinine kinase, . Consider preanaesthetic blood sampling if apprpriate
how much blood can be sampled from a healthy individual (exotics)
Maximum of 10% of total blood volume may be sampled from a healthy individual.
We need to know the blood volume per kg of body weight
Only 5% should be sampled in sick/debilitated animals
Must consider blood loss through haematoma formation
Most patients are compromised
Avian Blood Sampling Volumes
Blood volume calculated as 10% bodyweight- Eg. 10ml circulating blood in 100g bird
Blood volume that can safely be taken in birds around 1% BW- Eg. 1ml sample collection in 100g bird, 3.5ml from 350g bird
Examples:
Canary – 0.2ml
Cockatiel – 1ml
African Grey Parrot – 5ml
Harris Hawk – 10ml
Mute Swan – 100ml
Consider post sampling haemorrhage
Reptilian Blood Sampling Volumes
Lower blood volume than equivalent sized mammal/bird
Blood volume calculated as 4-8% bodyweight- Eg. 4-8ml circulating blood in 100g reptile
Sample volume that can safely be taken around 10% of Blood volume
This equates to approximately 0.5% bodyweight
Eg. 0.5ml from 100g snake, 3.5ml from 700g lizard
exotic Mammalian Blood Sampling Volumes
Blood volume calculated as 6-8% bodyweight- Eg. 6-8ml circulating blood in a 100g mammal
Blood volume that can safely be taken in mammals around 1-2% of BW
Examples:
Dwarf Rabbit – 5ml
Standard Rabbit– 20ml
Giant breed Rabbit – 36ml
Ferret – Jill 5ml Hob 10ml
Guinea Pig – 8ml
Rat – 2-3ml
Mouse – 0.2-0.3ml
Hedgehog 2-6ml
venipuncture sites in exotic mammels-
Cranial Vena Cava- Blind technique
Anaesthesia (or moribund animals)
Landmarks- clavical
use short needle to avoid heart, slightly longer with ferret
Ferret, Guinea pig, Hedgehog
Jugular Vein
Conformation may limit- short neck in guinie pigs
Stress
Respiratory compromise- rabbits breathing compromised in this position- glottis disloged from soft pallet
Cranial pressure can be increased by occluding the jugular
Rabbits, Ferrets, Hedgehogs , Other rodents
Cephalic-
As per dogs/cats
Conformation may limit
Gentle restraint
Small blood samples
Rabbits, Ferrets, Guinea Pigs and other hystricomorphs, Hedgehogs , Other rodents
Lateral Saphenous-
Ideal in rabbits
Often smaller blood samples
Lateral hind leg – cranial to hock
Prone to collapse
Lateral & Dorsal Tail Veins
Rats & Mice
Vasodilation helpful- warm tail in waterbath, anethetic agent, tourocate
Avoid in Gerbils (tail slip)
Marginal Ear Vein
Rabbits, some deer
Small Volumes
Vasodilation helpful- warm ear with hand
Head shaking can->vein laceration- EMLA/Local anaesthetic
venipuncture sites in birds
Basilic/Wing/Brachial/Ulnar Vein-
ventral aspect of elbow
Bend the needle- not much sorft tissue
Very fragile vein prone to haemorrhage- Can bruise easily
Good for: most bird spp. esp if under GA
Less easy in: very small or wriggly patients
Medial Tarsal Vein-
not GA needed
Good for: most bird spp. esp waterfowl, gulls, Less easy in: Raptors (talons), corvids(scaly legs), v small passerines (small)
Right Jugular Vein-
Not all birds have a left jugular or is v. small
Jugular apterium- one of the bare spaces between the feathered areas on the body of a bird.
More difficult for left handed people
Good for: Small passerines/psittacines/ raptors/ corvidsNot in: Pigeons (have no jugular vein or apterium, cervical plexux instead), Waterfowl ( no jugular apterium), Gulls
sites of venipuncture in Chelonians
Jugular vein-
Regarded as gold standard- low risk of lymp dilution
Dorsal branch runs in line with ear (auricular) scale
Ventral branch runs below ear scale
Both v superficial
Handling key – can be very stubborn
Pressure after sampling very important- Can hit carotid artery- Can get haematomas due to clotting defects common in reptiles
Subcarapacial sinus-
Blind technique- Good for larger samples
Higher risk of lymphodilution c/f jugular
Bend the needle
Can use even in drawn in/small animals
Dorsal tail vein-
Dorsal midline
Palpate spine
Smaller volumes
Higher risk of lymphodilution c/f jugular
Brachial plexus-
Useful in larger tortoises
Leg drawn out
Can feel tendon behind carpal joint
venipuncture sites in squamates
Ventral Tail Vein-
Care if species which autotomizes-
Avoid hemipenes- go a quarter of the way down the tail
Midline (like a cow!)
Hit spine and draw back
Reasonable sample sizes
Common in lizards
Only in large snakes
Care if species which autotomizes
Midline (like a cow!)
¼-1/3 way down to avoid hemipenes
Hit spine and draw back
Reasonable sample sizes
Cardiocentesis-
Safer than it sounds
Some clinicians prefer to sedate
Locate using doppler
Stabilise heart
Enter from caudal direction
Advance the needle into the ventricle
Allow to fill with the cardiac output
biochemicla markers of inflamation in exotics
Protein electrophoresis
Albumin:Globulin ratio
Acute phase proteins (Early stages of use in exotics)
Total Protein
Not very sensitive as doesn’t differentiate between different proteins
Includes albumin and globulins
↑ Haemoconcentration, Inflammation, vitellogenesis, lipaemia
↓Malnutrition/absorption, parasitism, hepatopathy, nephropathy, enteropathy, skin losses, lymph dilution
Albumin in exotics
Difficult to assay accurately in practice- Low levels compared to domestic patients, Pre-albumin can affect analysis of albumin
Protein Electrophoresis most accurate way to assay proteins- interpretation needs to be species specific expert
Avian/Reptilian
↑ Haemoconcentration, vitellogenesis, follicular stasis
↓Malnutrition/absorption, parasitism, hepatopathy, nephropathy, enteropathy, skin losses
Globulins in exotics
Avian
Alpha globulins (acute phase proteins)
↑ Acute inflammation, reproductively active female (vitellogenesis)
↓hepatic disease but rarely seen
Beta globulins (acute phase proteins & immunoglobulins)
↑ Acute inflammation, Acute or chronic disease response eg Aspergillosis, psittacosis
Gamma globulin (immunoglobulins)
↑ Chronic inflammation, Acute or chronic disease response eg Aspergillosis, psittacosis
Mammals
Rabbits with E cuniculi often have higher gamma globulins
Decreased Albumin:Globulin Ratio
Alanine Transferase (ALT) & Alkaline Phosphatase (ALP) in exotics
ALT
Widely used as marker of hepatocellular injury in domestic patients
Not released in liver damage in exotic species so of little use
ALP
No use in relation to cholestasis
Purely a marker of bone damage and turnover, elevated in young animals & MBD
Aspartate aminotransferase (AST) in exotics
Elevated in liver and muscle damage
Must assess alongside Creatine Kinase for muscle damage and GLDH for liver damage
↑Hepatocellular damage, tissue damage
Creatine Kinase (CK) in exotics
Avian
Can be elevated from difficult venipuncture of muscle damage/necrosis
↑tissue damage (can see large magnitude increases), IM injections, catabolic states
Short half life (16 hours)
if very high pay attention
Reptilian
Present in skeletal and heart muscle and less in kidneys
↑ with muscle damage and post traumatic venipuncture
Mammalian
In skeletal, smooth & cardiac muscle
↑ with any disease process associated with muscle
Glutamate Dehydrogenase (GLDH) in exotics
Very short half life
specific to liver damage but not sensitive to it
Avian
Specific for hepatocellular damage but not very sensitive
↑Hepatocellular damage
Reptilian
Useful indicator of hepatocellular damage but limited evidence
Mammalian
Not widely used
Gamma-glutamyl transferase (GGT) in exotics
Marker of cholestasis in domestic patients AND exotics
Also present in renal tissue in exotics- Excreted into urine so can’t be picked up on blood biochemistry
Avian
Specific for hepatocellular damage but not very sensitive
↑Biliary Stasis (Similar to ALT in mammals)
Bile acids in exotics
Mammals
Circadian rhythm
In rabbits caecotrophy makes fasted sample collection challenging so hard to tell if elevated levels relevant
Only useful if consistently raised
Hepatic coccidiosis in rabbits
Avian
Reliable indicator of liver function
Beware post prandial increases up to 4.5 x normal range
Some species lack gall bladder
↓ common in birds with microhepatica, poor feathering, overgrown malformed beak
↑Hepatic insufficiency
Reptiles
May be useful – major bile acid varies across reptilian taxa
Much reduced post prandial elevations c/f birds (max 1.7 x range)
Bile Pigments in exotics
Bilirubin
Some birds produce this and see inconsistent elevations with liver disease
Some birds cannot produce bilirubin as most don’t have biliverdin reductase
Generally don’t see icterus in avian patients
Biliverdin
Biliverdin primary bile pigment/end product of haemoglobin in reptiles
Reptiles lack biliverdin reductase enzyme to produce bilirubin from biliverdin
No commercial assay- so detect with Biliverdinuria-green urin
Glucose in exotics
Handheld vs laboratory assays
Human glucometers tend to underestimate) vs Veterinary glucometers oversestimate
Mammals
Herbivores vs carnivores
Rabbits – useful prognostic indicator
↑ Stress, pain, food intake, severity of disease, GI obstruction vs stasis
Ferrets (Guinea Pigs)- ↓ Insulinomas, septicaemia, severe liver disease, starvation- sick ferrets should have glucose checked
Reptiles
Very variable with spp, nutrition, environment, season
↑ with stress, high temps, pancreatic neoplasia and rarely DM
↓ anorexia, malnutrition, severe hepatic dysfunction, sepsis
Lactate in exotics
Produced during times of tissue hypoperfusion
Serial monitoring rather than single value for porgnosis
↑ shock, low cardiac output, acute liver failure, sepsis, seizures
Mammals
Ranges not well defined – rabbits may have higher lactate values than other mammals
Reptiles
Is a marker of anaerobic metabolism, can be used to assess physiological stress
Birds
Capture myopathy
Uric Acid in exotics
Is useful marker to detect renal insufficiency
Not v sensitive s doesn’t elevate quickly
Avian
Main indicator of renal function
↑ Renal disease, postprandial, esp in carnivores, dehydration, egg production, gout
↓Malnutrition/absorption, liver disease
Reptiles
Also primary end product of protein metabolism
Dependent on reptile’s natural environment
Terrestrial reptiles are uricotelic, Aquatic usually ureotelic
Mammals
Not useful – mammals excrete the water soluble nitrogenous waste product urea
Urea in exotics
Mammals
Main marker of renal function alongside creatinine
↑dehydration, renal dysfunction (NB once 50-75% nephrons affected)
Rabbits
Diurnal fluctuation (related to caecotroph ingestion)
Peaks in late afternoon/evening
Avian
Limited value
↑ 4-5 x with dehydration, not sensitive for detecting renal insufficiency
Reptiles
Less useful parameter except for in tortoises
↑dehydration as urea can be resorbed across the bladder to reduce water losos
Creatinine in exotics
Levels low consistently in birds and reptiles
Don’t change with renal insufficiency
Calcium
Total Calcium
Ionised (c. 45%) – metabolically active (can diffuse into cells)
Bound to Albumin (c. 40%) Being transported – not metabolically active
Associated with other ions eg Lactate and Phosphate 10-15% - biologically inert
Essential to measure Ionised calcium
Ca:P ratio important
In egg laying females
See huge elevation in Calcium to produce egg shell
This is predominantly Bound and not metabolically active
Mammals
↑ neoplasia, renal failure, impaired excretion, Ca-rich diets (rabbits/G pigs)
Hypocalcaemia
Again total Ca can be misleading if iCa low but total Ca normal
Mechanisms of cell injury
Anything that causes cell injury disrupts cellular homeostasis.
Cells can be injured by myriad causes, both from intrinsic and extrinsic sources.
Damage occurs to cells through one or a combination of of four basic mechanisms:
Adenosine triphosphate (ATP) depletion
Permeabilization of cell membranes
Disruption of biochemical pathways, especially those of protein synthesis
DNA damage
Damage occurs to cells through one or a combination of of four basic mechanisms:
Adenosine triphosphate (ATP) depletion
Permeabilization of cell membranes
Disruption of biochemical pathways, especially those of protein synthesis
DNA damage
causes of atp depletion
Hypoxia/anoxia- oxygen essentail to make
Specific toxins
causes of Permeabilization of cell membranes
Hypoxia/anoxia
Reactive oxygen species (free radicals)
causes of Disruption of biochemical pathways
Hypoxia/anoxia
Reactive oxygen species (free radicals)
causes of DNA damage
Endogenous causes
Reactive oxygen species (free radicals)
Replication errors
Exogenous causes
Ultraviolet light
X-rays and gamma rays
Certain plant toxins
Viruses
Morphology of cell injury: The common appearance of an injured cell is-
Due to
Failure of ATP-dependent enzymes and pumps/channels
Increased membrane permeability
Acute cell swelling is also known as hydropic degeneration
Particularly in the liver (hepatocytes) and kidney(renal tubular epithelial cells
In other cell types such as the skin (keratinocytes), cell swelling from influx of water is called ballooning degeneration.
Can be reversible if inciting factor/agent is gone
Three key histopathological changes in acute
early and reversible cell injury visible with light microscopy are:
Cell swelling
Cytoplasmic vacuolation
Hypereosinophilia
Organelle changes, membrane blebs and myelin figures are typically only seen using ultrastructural examination (transmission electron microscopy)
cell injury: Fatty change
Physiology of lipid metabolism
Lipid is delivered to the hepatocyte from dietary sources or body fat stores in the form of free fatty acids (FFAs).
A small amount of FFAs are also synthesized in the hepatocyte itself from acetate.
Some of the FFAs are utilized for the synthesis of cholesterol and phospholipids, and some may be oxidized to ketone bodies (1).
Most of the intracellular FFAs are esterified to triglycerides (2).
Once triglycerides are produced, they must be complexed to a lipid acceptor protein (or apoprotein) prior to export from the cell (3) as lipoproteins.
This requires protein and energy
Triglycerides may accumulate if the balance between the synthesis of triglycerides and their utilization or mobilization is deranged. When intracellular triglycerides accumulate, a fatty liver results.
Hypoxia
Protein synthesis- Aflatoxin, Carbon tetrachloride
Outcomes of cell injury
Four possible outcomes
Repair
Adapt- chronic low grade injury
Senescence- dna damage
Death
Dysplasia -> dna damage- neoplasia
Unsurprisingly, mitochondria, which are the organelles most susceptible to injury, are thought to direct many of the processes of cellular adaptation, senescence, and programmed death.
The point at which reversible cell injury becomes irreversible is debateable, but likely is dependent on calcium haemostasis within the cell
cellular adaptation
In the face of chronic sub-lethal injury (or stressor), cells can adapt involving the following mechanisms:
Hypertrophy
an increase in cell size by virtue of an increase in number and size of organelles
Hyperplasia
an increase in cell number that only those cells capable of mitosis can undergo
Atrophy
a decrease in cell size by virtue of a decrease in number and size of organelles
Metaplasia
a change from one differentiated cell type to another of the same germ layer (e.g., from ciliated epithelium to stratified squamous epithelium in the respiratory tract)
Dysplasia
abnormal differentiation with features of cellular atypia
These are physiologically normal responses, however can result in their own pathologies.
Hypertrophy in cell adaptation
an increase in cell size by virtue of an increase in number and size of organelles
Cellular hypertrophy is the process by which postmitotic cells, such as cardiac or skeletal myocytes, can grow.
Physiological response to increased workload and/or hypoxia.
In the heart, in the short term this is compensatory resulting in increased capacity.
In the long term, accompanying changes, can lead to decompensation of the affected organ.
The classic example in veterinary medicine is hypertrophic cardiomyopathy (HCM) in cats.
The complex pathophysiology of HCM is still unclear.
Reversible if due to treatable disease
hyperthyroidism
Do not confuse hypertrophy with hyperplasia
Hyperplasia
an increase in cell number that only those cells capable of mitosis can undergo
Physiological response to increased, often hormonal, stimulus
Puberty and pregnancy
Thyroid hyperplasia - Goitre
Maternal iodine deficiency will result in hyperplasia (and hypertrophy) of thyroid follicular epithelial cells in ruminants
Rarely see it as bad as the image to the right, so should always weight and store thyroid glands (fixed and frozen) in cases of perinatal/neonatal death in ruminants
Non-neoplastic enlargement of a tissue.
Hyperplasia is often the result of hormonal influences (e.g. benign prostatic hyperplasia, perianal gland hyperplasia), tissue injury (e.g. regenerative nodules in the liver, granulation tissue with fibroplasia) or antigenic stimulation (lymphoid hyperplasia).
Aspiration of hyperplastic lesions:
Higher than expected cellularity
Cells may display some mild criteria of malignancy
Mildly increased N:C ratio
Darker blue cytoplasm
More prominent nucleoli
Finer chromatin than normal
Atrophy
a decrease in cell size by virtue of a decrease in number and size of organelles
Physiological response to lack of use/innervation/stimulation
Classic example is the small liver of the puppy with a portosystemic shunt
Metaplasia
a change from one differentiated cell type to another of the same germ layer (e.g., from ciliated epithelium to stratified squamous epithelium in the respiratory tract)
Typically from a specialised and/or fragile type (ciliated or simple cuboidal) to a less specialised, more protective type (eg: stratified squamous or goblet cell)
Vitamin A deficiency in parrots results in squamous metaplasia of respiratory and upper GIT epithelium
Poorly understood mechanism
Results in hyperkeratosis of oral cavity, conjunctiva, nasal lacrimal duct, upper alimentary tract, and respiratory tract
Ducts of glands can become blocked by keratin, often resulting in huge keratin granulomas and rhinoliths
Dysplasia
abnormal differentiation with features of cellular atypia
When applied to epithelium, dysplasia implies an increase in the number of poorly differentiated or immature cells
Can be a precursor to neoplasia
Microscopic features:
Variation in size (anisocytosis)
Variation in shape (poikilocytosis)
Hyperchromatic nuclei
Large nuclei (karyomegaly)
Increased size or number of nucleoli
Mitotic figures
Making the call between dysplasia and neoplasia is thus difficult
A continuum
Classic example is actinic keratosis on the pinna of white cats due to UV light
A carcinoma will breach the basement membrane
Dysplasia = disordered growth
Common in epithelial tissue secondary to inflammation or irritation.
Loss of uniformity of the individual cells
Disordered architectural arrangement of the cells.
Atypical cytologic features:
Nuclear to cytoplasmic asynchrony
Increased cytoplasmic basophilia
Anisokaryosis and anisocytosis.
Dysplasia can be cytologically difficult to distinguish from neoplasia as dysplastic lesions often contain more criteria of malignancy than strictly hyperplastic lesions.
labile cells
cell with rapid turnover
cells that continuously multiply and divide throughout life. This continual division of labile cells allows them to reproduce new stem cells and replace functional cells that are lost in the body.
quiesecent cells
a cellular state in which a cell remains out of the cell cycle but retains the capacity to divide. The unique ability of adult stem cells to maintain quiescence is crucial for life-long tissue homeostasis and regenerative capacity
liver ect
terminally differentaited cells
neurons
in the course of acquiring specialized functions, has irreversibly lost its ability to proliferate
stem cells
an undifferentiated cell of a multicellular organism which is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation
Senescence
Senescent cells are somatic cells that stop dividing- previously laibile or quessent cells can become senescent
Senescent cells remain metabolically active
Signals that induce senescence are typically due to DNA damage and/or tumour suppressor genes
mediated by p53-21 or p16
p53 tells damaged cells to stop
causes:
geonimoc instability
telomere attrition- aging causes these to get shorter
epigenetic alteration
loss of proteostasis
deregulated nutrient sensing
mitochondrial dysfunction
cellular senesence
stem cel exhastion
altered intracelleular communication
describert the Morphological appearance of cell ageing
Long-lived post mitotic cells (terminally diferentiated)- Neurones and muscle- will see Lipofuscin
Senescent cells- Heterochromatin (dense and innactive, non replicating chromatin) accumulations
seen by Transmission electron microscopy
Not clinically relevant
Biochemical markers of senescence- Lack proliferation markers
Senescence-associated secretory phenotype (SASP)
Research orientated
Lipofuscin in the context of cell aging
Wear-and-tear pigment
Normal accumulation over time of lipoprotein in secondary lysosomes
May accumulate excessively in certain circumstances- Phalaris poisoning in ruminants- the pigment wouth be seen in cytoplasm of neurons
Intracellular, golden-brown, globular
Ceroid- Very similar to lipofuscin but only accumulates in disease states- rare to see
Brown gut in dogs with vitamin E deficiency
Intracellular and extracellular
Ceroid
Very similar to lipofuscin but only accumulates in disease states- rare to see
Brown gut in dogs with vitamin E deficiency
Intracellular and extracellular
Lysosomes
membrane-bound cell organelle that contains digestive enzymes. Lysosomes are involved with various cell processes. They break down excess or worn-out cell parts. They may be used to destroy invading viruses and bacteria.
Intracellular
Membrane-bound vesicles
Contain enzymes
Genetic disorders- lysosomal storage disorders- effects the brain- quite rare
two types of intracellular pigment
exgenous- carbon, tattoo ink-can be seen in post mortem of lympnodes- vaccine adjuvant carotenoids, tetracyclins-
endogenous- heamatogenous, non-heamatogenous
Endogenous pigmentation – non-haematogenous
Lipofuscin and ceroid
Melanin- Incidental colouration: Leptomeninges, Pig lungs - melanosis- distingushed form melanoma by flat symetrical appearence
Hyperpigmentation- Endocrine skin disease (unclear why)
Melanoma
Hypopigmentation- Vitiligo- immune sytstem attacks melanin, Melanin incontinence: Some skin diseases of dermo-epidermal junction- could be indication od disease in dermis(pemphigus)
Endogenous pigmentation - haematogenous
from Blood-
Haemoglobin
Haemosiderin- brown pigment form broken down blood in macrophages- heamociderophages- stain blue. happens with heamorage. can indicate heart failure when found in the lungs
Haematoidi
Porphyria- Heme synthesis disorder
Deposition of porphyrin pigments in tissues
can turn bone pinker and makes them florese
cattle teeth may turn brown pink
Parastitic haematin- Liver fluke eat blood and pass it out as parasitic haemotin- seen in liver
Methaemoglobinaemina- Heme iron is oxidized from the ferrous (2+ ) to the ferric (3+ ) form
Methaemoglobin is constantly being formed, but it is reduced to haemoglobin by the methaemoglobin reductase pathway
Marked oxidant exposure may promote the formation of methaemoglobin.
Oxidative agents include gallotannin metabolites- Red Maple/Acercan induce this in horses
Associated with Heinz bodies (see haematology lectures next week)
May also see haemolytic crisis
The blood and mucous membranes may appear brown when >10% of the total hemoglobin has been converted to methemoglobin
Rare genetic disease in humans
causes brown pigmant in skin
Carbon monoxide
CO bind haemoglobin, forming carboxyhaemoglobin
Much stronger binding than oxygen and slow to revert
Cherry red mucous membranes, muscle and brain
Bile and breakdown products- juandice
Endogenous pigmentation – post mortem
Haemoglobin imbibition- freeze thaw artifact, animal may have had masave haemorage then not pm-ed for a number of days
Psuedomelanosis
blue green streaking of tissue and facea
Action of hydrogen sulphide (bacteria) on haemoglobin changes into FeS (ferris sulphide)
Exogenous pigmentation - carotenoids
Carotenoids are found in leafy vegetables and in horses and Jersey cattle impart a yellow colour to adipose tissue and lipid-laden organs.
dont confuse with yellow fat disease
Calcification
Pathological calcification = deposition of calcium salts in soft tissues - typically as phosphates and carbonates
Metastatic calcifi
cation is due to increased circulating calcium levels
Dystrophic calcification is secondary to necrosis
Liquefactive/lytic necrosis
Cells are lysed, and the necrotic tissue is converted to a fluid phase
Caused by:
Bacteria
Fungi- cryptococcus neoformans in the brain
Most common in the CNS- cant really get any other type of necrosis
Due to hypoxia
Large amount of cells and cell membranes with little connective tissue so nithing really holds it in
Gross-
Soft, viscous focus, often with cavity containing creamy-yellow material (pus).
Histo:
Cell debris, eosinophilic fluid
Very messy- hard to tell what struture is being observed
Coagulative necrosis
Tissue architecture/basic outline of necrotic cells is preserved. Suggestive of:
hypoxic injury
bacterial toxins
chemical toxins
Gross- Often well demarcated
Especially if due to infarction
Rim of inflammation
Histo-
Overall tissue architecture preserved, often with retention of basement membranes
Necrotic cells display typical histologic evidence of necrosis
Inflammation
Early attempts at healing- Especially in kidney if basement membrane intact
Caseous necrosis
Cheese-like
A chronic coagulation necrosis- Typically due to body’s inability to remove the agent
- intracellular bacteria
Common in birds and reptiles - Reduced amounts of myeloperoxidase in heterophils (neutrophils).
Gross:
Friable, granular, white appearance
Typically encapsulated
Abscess/granuloma/pyogranuloma
Histo:
Loss of architecture- mush of calcified tissue
Central accumulation of remnants of lysed leukocytes
May have border of granulomatous inflammation and outer fibrous tissue (‘granuloma’)
Often dystrophic calcification centrally.
A classic bacterial example is
Corynebacterium pseudotuberculosis
types of gangrenous necrosis
wet/moist, gaesious, dry
Gangrenous necrosis
Three types
Wet/moist:
Area of necrotic tissue further degraded by liquefactive action of saprophytic bacteria.
Death of animal may occur due to toxaemia/ sloughing of tissue
Gross: soft, moist, red-brown to black. +/- gas, putrid odor (hydrogen sulfide).
Gaseous:
Bacteria proliferate and produce toxins in necrotic tissue.
Usually anaerobic bacteria eg. Clostridium perfringens/ septicum.
Bacteria introduced by penetrating wounds, necrotic tissue becomes anaerobic, bacterial growth and toxin production.
Gross : dark red-black, gas bubbles, fluid and haemorrhagic exudate.
Dry:
Coagulation necrosis secondary to infarction followed by mummification (dehydration).
Usually lower portion of extremity (tail, ears, udder).
Ingested toxins- ergot, fescue, and frostbite. Peripheral arteriolar constriction and damage to capillaries. Thrombosis and infarction (also direct freezing injury and ice crystal formation in frostbite).
Necrotic tissues depleted of water eg. by low humidity, resulting in mummification.
NO bacteria proliferation.
Gross: dry, shrivelled, brown-black. May slough.
wet/moist gangrenous necrosis
Area of necrotic tissue further degraded by liquefactive action of saprophytic bacteria.
Death of animal may occur due to toxaemia/ sloughing of tissue
Gross: soft, moist, red-brown to black. +/- gas, putrid odor (hydrogen sulfide).
gaseous gangrenous necrosis
Bacteria proliferate and produce toxins in necrotic tissue.
Usually anaerobic bacteria eg. Clostridium perfringens/ septicum.
Bacteria introduced by penetrating wounds, necrotic tissue becomes anaerobic, bacterial growth and toxin production.
Gross : dark red-black, gas bubbles, fluid and haemorrhagic exudate.
can occur post death
dry gangerenous necrosis
Coagulation necrosis secondary to infarction followed by mummification (dehydration)- trapped animals in dry enviroments may display this
Usually lower portion of extremity (tail, ears, udder).
Ingested toxins- ergot, fescue,
frostbite- Peripheral arteriolar constriction and damage to capillaries. Thrombosis and infarction (also direct freezing injury and ice crystal formation in frostbite).
Necrotic tissues depleted of water eg. by low humidity, resulting in mummification.
NO bacteria proliferation.
Gross: dry, shrivelled, brown-black. May slough.
Fat necrosis
Nutritional, enzymatic, traumatic, and idiopathic.
Focal areas of fat destruction.
Nutritional fat necrosis
Also known as steatitis or yellow fat disease
Diet high in unsaturated fatty acids and low in vitamin E or other antioxidants
ROS production and lipid peroxidation.
Enzymatic necrosis of fat
Pancreatitis
Release of activated pancreatic lipases which liquefy adipocytes
Fatty acids combine with calcium to form chalky white areas (saponification)
Faint outlines of cells with basophilic calcium deposits and inflammation
Traumatic necrosis of fat
Crushing
Idiopathic fat necrosis
Necrosis of abdominal fat of Jersey/ Guernsey breeds
Large masses of necrotic fat in mesentery, omentum and retroperitoneum.
May cause intestinal stricture/stenosis.
Gross:
Firm, white, chalky.
Histo:
Necrotic fat not lost in processing.
Eosinophilic to basophilic (if FFA’s react with Ca2+ to form soap) necrotic adipocytes.
Nutritional fat necrosis
Also known as steatitis or yellow fat disease- dont confuse with normal yellowing in horses
Diet high in unsaturated fatty acids and low in vitamin E or other antioxidants- ROS production and lipid peroxidation.
Enzymatic necrosis of fat
Pancreatitis
Release of activated pancreatic lipases which liquefy adipocytes
Fatty acids combine with calcium to form chalky white areas (saponification)
Faint outlines of cells with basophilic calcium deposits and inflammation
hiseologically will show as spaces for fat surrounded by inflamation and heamorage. soponificaition will leave blue material
Traumatic necrosis of fat
Crushing
Idiopathic fat necrosis
Necrosis of abdominal fat of Jersey/ Guernsey breeds-
Large masses of necrotic fat in mesentery, omentum and retroperitoneum.
May cause intestinal stricture/stenosis.
Gross:
Firm, white, chalky.
Histo:
Necrotic fat not lost in processing.
Eosinophilic to basophilic (if FFA’s react with Ca2+ to form soap) necrotic adipocytes.
Fibrinoid necrosis
Blood vessel wall necrosis- associated with inflammation = vasculitis
Antigen and antibody complexes deposition in arterial walls and fibrin leakage.
Histo:
Bright pink, amorphous hyaline (glassy)
Thrombosis- inflamation
hypertoropic epithelil cells in lumen
Haematopoeisis
Definition - The formation of the cellular components of blood
Location - In the mature animal this occurs primarily in the bone marrow
Maturation, activation and some proliferation of lymphoid cells occurs in thymus, spleen and LNs
Liver and spleen can also be recruited to produce blood cells – “extramedullary haematopoeisis”
Erythropoeisis
the production of red blood cells.
Tissue hypoxia detected in peritubular interstitial cells kidney
These cells produce erythropoietin (EPO)
EPO binds to BLU-E/CFU-E/rubriblasts stimulating signalling cascade
Results in differentiation and survival of erythroid progenitors
Leading to increased production of mature RBCs
Other growth factors involved include IL-3, GM-CSF and Thrombopoeitin (TPO)
Hormones that promote erythropoiesis in combination with EPO – thyroid hormone, androgens, glucocorticoid
this means significant kidney disease can result in anemia- chronic renal disease
Myelopoeisis
the production of leukocytes in blood, such as MONOCYTES and GRANULOCYTES. This process also produces precursor cells for MACROPHAGE and DENDRITIC CELLS found in the lymphoid tissue.
Stimulated by factors such as IL-3, GM-CSF and G-CSF
Act on CMPs/GMPs to differentiate into myeloblasts
Production massively upregulated in response to inflammatory stimulus (eg macrophage inflammatory protein-2, IL-8, C5a
Eosinophil differentiation – TH2 lymphocytes involved by producing Il-5
Basophil differentiation – IL-3 and others involved
Thrombopoeisis
the formation of platelets in the Bone marrow
Stimulated by thrombopoietin (TPO) which is produced mainly in liver
TPO stimulates megakaryocyte production and survival from megakaryoblasts
Other factors involved include IL-3, GM-CSF, IL-11 and EPO
animals anemic due to iron deficiency will have increased no. of platlets
animals with liver disese still produce adiquate platlets
Neutrophils
recognised by segmented nucleus
granulocites
Vital part of innate immune system
“First responders” – hallmark of acute inflammation
Methods of attack – phagocytosis, degranulation and extracellular traps (NETs)
Eosinophils
recognised by pink granuals
Involved in response to parasitic infection
?Involved in response to some viral infections- not clasically assositated with this though
Major mediators of allergic responses
Basophils
Play a role in reactions to parasites and allergic reactions
Release histamine (along with mast cells)
Lymphocytes
mononuclear cells. thin rim of cytoplasm. smallest luekocyte
Adaptive immune response
T cells – cell mediated immunity
B cells – humoral (antibody) production
NK cells – innate immune system
Many functions!
Monocytes
can be confused with neutrophils of leukocytes. bigger with more blue colouring an dmore cytoplasm
Orchestrators of the immune response
Phagocytosis and microbicidal
Regulates immune responsevia cytokines
Scavenger role
Secretory
Leave circulation to become tissue macrophages
what can be diagnosed from Blood film examination
Clinically significant thrombocytopenia
Regenerative vs non-regenerative anemia
Spherocytes
Rouleux vs agglutination
Hypochromia (iron deficiency)?
Check machine leukocyte differentials
Left shifts
How to perform a manual platelet count:
Must be performed at x1000 (ie x100 oil lens)
Count number of platelets in 10 x1000 fields of view
Take average and multiply by 15-20
This gives an approximate count x10^9/L
Don’t forget to correlate with clinical signs (eg petechiae)
Remember clinically significant bleeding 2nd to thrombocytopenia unlikely unless count <50x10^9
Rule of thumb – if you can find platelets easily on the film patient unlikely to be bleeding from thrombocytopenia
Try and perform the count in the monolayer – not too thin and not too thick
how to distinguish if the patient’s anemia regenerative or not?
Key to answering this question is to assess for the degree of polychromasia
Polychromatic red cells larger and bluer – retained RNA, released earlier from bone marrow- indicates regenerative anemia
spherocytes
Spherocytes are red blood cells that are sphere-shaped rather than the usual round doughnut shape. Spherocytes are more fragile than normal red cells and their presence is accompanied by anemias of varying severity.
Dogs not cats
Must look in right area of blood film – in monolayer where you can compare to red cells with central pallor
Not in tail of film – everything will look like spherocytes!!
Spherocytes appear smaller, perfectly round and more densely staining
Their presence in significant numbers is suggestive of IMHA
Rouleux vs Agglutination
Agglutination (“bunch of grapes”)- immune mediated anemia
Rouleux (“stack of coins”)- high protien level
Hypochromia
Iron deficiency
Increased central pallour
Pale staining
Frequently fragile red cells (schistocytes, acanthocytes and keratocytes)
Often associated thrombocytosis
What is a left shift and how do I recognise it?
an increase in the number of immature cell types among the blood cells in a sample of blood. Many (perhaps most) clinical mentions of left shift refer to the white blood cell lineage, particularly neutrophil-precursor band cells, thus signifying bandemia.
Release of earlier granulocyte precursors from marrow
Indication of increased neutrophil demand/consumption
Inflammation/infection
“Band” neutrophils
What should I confirm with an external lab for haematology?
Neoplastic cells
Toxic change?
Infectious agents?
Dysplastic change
Laboratory assessment of Erythrocytes:
Complete blood count (CBC)
Blood film examination
Ancillary tests
Measured Red Cell Parameters
Haemoglobin (Hb) (uses a biochemical method)
Red blood cell concentration (RBC/ul)
Mean cell volume (MCV); average size of RBCs
Calculated Red cell parameters: Haematocrit(HCT)
calculatedfrom those measured (HCT = MCV x RBC)
Equivalent of manual PCV
Calculated Red cell parameters: Mean corpuscularhaemoglobin(MCH)
calculated (MCH =Hbx10 / RBC)
Calculated Red cell parameters:Mean corpuscularhaemoglobinconcentration (MCHC)
MCHC=Hb/HCT
analysers in haemotology
Red cell distribution width (RDW) – indication of variation in red cell size- bone marrow is trying to respond to an anema, larger cells are being released
Reticulocyte counts/percentage – measure of regeneration, how many immature cells are being released from bone marrow
Reticulocyte Hb – potential marker for iron deficiency
Plateletcrit (PCT) – equivalent of HCT for platelets
Packed cell volume (PCV)
PCV – percentage of red cells in a volume of blood. Manual technique.
Centrifuged whole blood, red cells read as a % of column.
Buffy coat assessment
Plasma – clear/ straw or pink if haemolysed
Total proteins measurement
Blood film exam of RBCs
Evaluating 3 main things:
Red cell density – does it look anemic?
Red cell regeneration – is the marrow trying to regenerate?
Red cell morphology – are there any clues to the cause of an anemia? (Eg spherocytes, organisms etc)
is the patient anaemic?
Very subjective
Will depend on how the blood film is made
Use as a crude quality control measure – does the red cell density appear compatible with the HCT provided by our analyser?
why is it good to differentiate between regenerative and non regenerative anemia
Regenerative anemia – relatively short differential diagnosis list
Non-regenerative - long differential diagnosis list
Regenerative anemia signs
Anisocytosis
Polychromatophils- when stained with diff quick type stain. Reticulocytes- stained with methalyn blue. same thing. these are immature red celss that still contain ribosomes
mathalyn blue precipitates ribotsomes, making them reticulated. hence reticulocytes
these immature red cells are seen in regenerative anemia as bone marrow is putting them out to regenerate the red blood cells
Nucleated RBC- not cliniclaly significant in birds and reptiles. earlier stage of maturation of ed blood cells. shows bone marrow is trying to regenerate red blood cell count in the case of re generative anemia
Howell-Jolly bodies- Are nuclear remnants. usually would be removed in bone marrow except in this case
Reticulocytes and Polychromatophils
On a Diff – Quik or Giemsa stained smear, young red cells containing reticulin show up as larger, bluer cells: polychromatophils
Stain the same cells with New Methylene Blue, and you can see the reticulin : the cells are then called reticulocytes
THEY ARE THE SAME CELLS
RBCs – Morphological abnormalities to help distiguifh causes of anemia
Most helpful/specific-
Spherocytes
Agglutination
Eccentrocytes
Heinz bodies
Hypochromia
Acanthocytes
Schistocytes
Less helpful/specific-
Echinocytes (crenated cells)
Keratocytes
Ovalocytes
Dacrocytes
Heinz bodies and eccentrocytes
sign of oxidative injury which can cause anemia. Haemoglobin is oxidised and pushed to cell margin, no longer functiona
eccentrocytes - cresent moon shape
heinz bodies- protruding heamoglobin, red nose shape
Paracetamol in cats, onions, some toxins (eg Zinc), diabetic ketoacidosis are some common causes of Heinz bodies/eccentrocytes
Acanthocytes
red cells with spicules (small uneaven projections)
form with alteration of lipid metabolsm which effects the cells membrane
Lipid disorders
Liver disease
Fragmentation injury (eg haemangiosarcoma- neoplams of blood vessels involving liver and spleen)
Schistocytes
Red cell fragments forming secondary to being squeezed through abnormal blood vessels (eg haemangiosarcoma) or being fragile (eg iron deficiency)
Hypochromic RBCs
This usually occurs when there is not enough of the pigment that carries oxygen (hemoglobin) in the red blood cells.
ancillary PCR (EDTA sample) tests are available for:
the haemotropic Mycoplasmas in cats
Babesia species in dogs
Ehrlichia and Anaplasma in dogs
FIV/FeLV
ancillary Serology (serum sample) is available for
Leptospirosis
Panleukopaenia,
canine parvovirus
equine infectious anaemia
Feline coronavirus
Slide agglutination test
To try and distinguish rouleux and true agglutination
The sample is examined microscopically after the addition of saline.
Rouleaux formations disperse, but agglutination persists.
Coomb’s test
Coomb’s reagent (containing antibodies to IgG, Igm and C3) in dilutions is reacted with washed patient red cells to detect those cells opsonised with antibody and complement
Opsonised cells binding antibody agglutinate
Agglutinated red cells fail to settle in round bottom wells
Significantly positive result provides support for immune mediated component to anemia
Faecal occult blood test
Up to 50% blood volume may be lost into the GI tract before it is grossly visible in the faeces.
These tests generally detect peroxidase activity (present in haemoglobin) and may be 50x more sensitive than visual examination.
They are prone to false positives due to meat diets, vitamin C and some vegetables (eg brassicas, cantaloupe melon (true, it’s on Wikipedia!!)).
It is advisable to feed restricted diets for at least 3d prior to the test. Which diets?
Traditionally white meat has been used
Rice / cottage cheese may be better
Commercial dry diets. Variable but if heat treated may be OK. Can always send in sample of dry commercial food at same time as faeces.
Compensatory mechanisms of tissue hypoxia
so a higher proportion of O2, which is carried by the Hb, is available to be released to the tissues.
Increased cardiac output: Serves to increase tissue oxygenation
Increased RBC production: Tissue hypoxia causes the release of the hormone erythropoietin from the kidneys.
Vasoconstriction: Shunting of blood away from tissues with low O2 demand (i.e. skin) to tissues with high O2 n demand (i.e. brain).
Potential clinical signs of anemia
Mucous membrane pallor
Lethargy
Exercise intolerance
Tachycardia
Tachypnoea
Collapse
Icterus
Melaena
Pica
RBC indices
Based on MCV values
Normocytic: erythrocytes of unremarkable size
Microcytic (low MCV): iron deficiency
Macrocytic (high MCV):
Presence of immature RBCs (ie marrow trying to respond)
some poodles,
in some bone marrow disorders
a common artefact in stored/old (usually posted) blood samples (RBCs swell up)
Normochromic
Hypochromic (low MCHC/MCH):
in iron deficiency/ poor iron incorporation (with microcytosis)
Presence of immature RBCs (are not fully haemoglobinised)
Hyperchromic (high MCHC/MCH):
Not physiologically possible
Always artefact (i.e. haemolysis)
regeneration of rbc
Regeneration is the body’s response to a fall in oxygenation
The kidneys respond by releasing erythropoietin (EPO)
This stimulates the bone marrow to increase red cell production
Takes 3-5 days, and younger red cells (polychromatophils/ reticulocytes) increase in circulation
Dogs and cats - expect reticulocyte response – horses retain retics in bone marrow, not seen in circulation; cattle/ sheep only with severe anaemia
Regenerative anaemia
Haemorrhage, haemolysis
Non-regenerative anaemia
Intra- and Extra-marrow diseases
Haemorrhage (external)
Melaena (GI bleeding)
Haematuria (Urinary tract)
Epistaxis (nose bleeds)
Post trauma/ surgery
Marked ectoparasitism
Some endoparasites (e.g. hookworm)
With acute haemorrhage, 3 – 5 days needed for a marrow response – before this, appears non or poorly regenerative : ‘pre-regenerative’
lab results:
Anaemia
initially regenerative BUT
prolonged external haemorrhage»_space;> iron deficiency»_space;> non-regenerative anaemia as iron supplies are exhausted
Proteins
will be normal in the acute stage, then decrease as fluid re-equilibrates
Haemorrhage (internal)
Cause not always obvious-
Bleeding tumours
Trauma
Bleeding disorders
Into tissue, cavities, lungs
Surgery
Respiratory” blood may be coughed, swallowed and appear as melaena
No iron deficiency
RBC breakdown products available for recycling
Proteins normal or raised
types of haemolysis
a cause of regenerative anemia
Extravascular- outside of blood vessels-
More common
Macrophages
Spleen and liver
± Icterus (jaundice)
Intravascular-
Acute, severe
Haemoglobinaemia
Haemoglobinuria
Ghost cells
+/- icterus
boith can occur at once- presentation is very accute
Haemolytic anaemia - Causes
Immune-mediated (common – primary verses secondary)
Infections (less common)
Babesia
Mycoplasma
Inherited RBC metabolic defects (rare)
Toxins
Severe Hypophosphataemia (rare)
Immune-mediated heamolitic anemia
One of the most common causes of anaemia in dogs
One of the most common immune-mediated Dz
Primary IMHA (AIHA)
Most common
Idiopathic
Breed predispositions
Young-middle aged
Female>male
clinical signs-
Lethargy, anorexia
Pale mucous membranes +/- tachycardia, bounding pulses, systolic murmur
±
Tachypnoea
Jaundice
Hepatosplenomegaly
Pyrexia, mild lymphadenopathy
Secondary IMHA
Infections
Neoplasia
Drugs
Systemic extra bone marrow disorders causing anemia
common
. Chronic inflammation
Most common cause
Usually mild/moderate
Fe sequestration and inflammatory mediators shorten erythrocyte survival
Endocrinopathies
Hypothyroidism
Hypoadrenocorticism
Chronic renal failure
Decreased erythropoietin production
Decreased RBC lifespan with uraemic toxins
At risk of GI haemorrhage
Primary intra-bone marrow disorders causing anemia –
less common
. Aplastic anaemia
Damage to stem cells, microenvironment or both
Non-regenerative anaemia, bicytopenia or pancytopenia
Idiopathic
Secondary to
Toxins (i.e. bracken fern)
Drugs (i.e. chemotherapy)
Infections (i.e. Parvo)
Immune mediated mechanisms
- Pure red cell aplasia/PIMA
Selective BM erythroid precursor damage
Non-regenerative anaemia
Immune mediated
Secondary to FeLV - Myelophthisis
Represents a space-occupying lesion in the BM that inhibits or displaces normal haematopoietic cells
NEOPLASIA usually
bone marrow derived but may originate elsewhere
Lymphoma, Metastatic disease
Non-regenerative anaemia, - Myelofibrosis
Proliferation of BM with fibrous elements that inhibits or displaces normal haematopoietic cells
Idiopathic
Secondary to other BM diseases
Often need BM biopsy for histopathology, not aspirate, to diagnose
ERYTHROCYTOSIS
having a high concentration of red blood cells in your blood. This makes the blood thicker and less able to travel through blood vessels and organs. Many of the symptoms of polycythaemia are caused by this sluggish flow of blood
Increased red cell mass, evidenced in increased :
Haemoglobin
Packed cell volume (PCV)
Haematocrit (HCT)
Red blood cell count (RBC)
Physiological-
Breed related
Reference intervals should be different for
Greyhounds vs other dogs
Thoroughbreds vs ponies
Relative
Dehydration (PCV up to 60%)
fluid loss with a stable red cell mass
Clinical signs may be present
Lab test abnormalities
increased serum total proteins
Often but not always increased serum sodium
increased urine specific gravity
PRIMARY(absolute)
Polycythaemia rubra vera
Bone marrow neoplastic dz
Clonal proliferation and maturation of RBCs WITHOUT normal feedback mechanisms
EPO low (in theory!)
neurological signs, seizures, paroxysmal sneezing, cardiopulmonary signs, retinal changes (high blood viscosity)
High PCV!! (>65
SECONDARY(absolute)
Hypoxia (altitude, heart/pulmonary dz)
Bone Marrow responds>EPO»RBC
Solid tumours
Renal carcinoma» EPO»»_space;RBC
WBC morphology
Left shift
Toxic change
Reactive lymphocytes
Atypical cells
Infectious agents
(NB – Analysers will not reliably pick out these things)
WBC Ancillary tests
Acute phase proteins (Dogs CRP, Horses Fibrinogen and SAA)
PCR and serology for infectious agents
Bone marrow aspiration/biopsy
PARR test (lymphoproliferative disease)
Flow cytometry (classification of leukemias)
Anti-neutrophil antibodies (uncommonly tested)
Neutrophilia
a higher neutrophil count in the blood than the normal reference range of absolute neutrophil count.
- TO MEET DEMAND
Infections
Immune mediated diseases
Inflammation
Neoplasia
(COMMON) - INDEPENDENT OF DEMAND
Bone marrow neoplasia = Leukaemia
(UNCOMMON)
- Persistence in circulation
Chronic stress
Glucocorticoids (steroids) - Redistribution (shift from marginating to circulating pool)
Excitement (epinephrine)
Stress(glucocorticoids)
increased blood pressure
Neutropenia: Causes
Increased demand (migration into tissue)
Bacterial sepsis, abscess
Endotoxaemia, tumour necrosis
Redistribution
In response to acute endotoxaemia (shift from circulating to marginating pool)
Decreased production
Bone marrow dz, Drugs
Increased destruction
Immune mediated
Neutrophils- Morphological assessment
Band neutrophils-
released with increased demand
Usually “U” shaped or “S” shaped nucleus with parallel sides ie minimal indentation/ segmentation
Toxic neutrophils-
Maturation defects
Seen with increased demand
Not necessarily sepsis, can happen with sterile demand
Pyothorax, pancreatitis, pyometra etc.
Dohle bodies
Foamy cytoplasm
Bluish cytoplasm
Toxic granules - rare
diagnosing toxicity is objective
LYMPHOCYTOSIS
- Increased production in response to increased demand
Persistent antigenic stimulation (fungal, protozoal, viral), Post vaccination, young animals - Increased production without demand
Lymphoid Leukaemia, Lymphoma - Redistribution
Excitement/acute stress (epinephrine response) (physiological; as for neutrophils)
inhibition of recirculation, release from the thoracic duct
Hypoadrenocorticism (10-20% of cases)
LYMPHOPENIA
Loss of lymphocytes
Loss of chylous fluid (rich in lymphocytes)
Protein losing enteropathy, chylothorax
Decreased production
Viral infections, lympholytic drugs (for chemotherapy)
Redistribution
Chronic stress, Glucocorticoids (steroids)
Trapped in lymph nodes
move from circulation into bone marrow and tissues
lymphocytolysis
MONOCYTOSIS
- Increased production by the bone marrow to meet demand
Infections, immune-mediated dz, inflammation, necrosis, sepsis, neoplasia - Increased production by the bone marrow without demand
Leukaemia (myelomonocytic) - Redistribution
Chronic stress, Glucocorticoids (steroids)
Move monocytes from the marginating to the circulating pool
EOSINOPHILIA
- Increased production in response to increased demand
Parasitic infection,
allergic disease”,
inflammation of mast cell rich tissue (intestines, skin, lungs, uterus) - Increased production without demand
Neoplasia (lymphoma, mast cell tumour, squamous cell carcinoma)
Hypereosinophilic syndrome
Peripheral eosinophilia & infiltration of organs with eosinophils without obvious cause
Eosinophilic Leukaemia (rare) - Hypoadrenocorticism
(lack of glucocorticoids)
BASOPHILIA
- Increased numbers due to increased demand
Hypersensitivities
drugs, food, insect bites/stings
Parasitism
especially Dirofiliaria,
but also GI parasites, fleas and ticks
Inflammation - Increased numbers without demand
Paraneoplastic (particularly with mast cell tumours)
Basophilic leukaemia (rare)
Stress leukogram
Leukocyte pattern due to the effect of increased cortisol
Classically neutrophilia +/-monocytosis with lymphopenia and eosinopenia
Most commonly seen dogs and cats
May be absent when expected eg Addison’s disease
Feline Haemotrophic Mycoplasmas
Endemic in UK
Feline Haemotrophic Mycoplasmas collectively known as haemoplasmas
Cause of Feline Infectious Anaemia - acute haemolytic anemia
Transmission method not definitively established - suspected fleas or aggressive interactions
higher prevalence in older male cats with out door access
transmission in blood - all blood donors should be screened
M. haemofelis (Mhf)- most pathogenic
mild to severe clinical disease in healthy cats
Candidatus M. haemomimutum (CMhm)- asymptomatic/milder disease
most likely to be clinical in immune compromised patients /concurrent disease (e.g. FeLV, FIV)
Candidatus M. turicensis (CMt)
could cause small reduction in RBC indices, unlikely to develop clinical anemia - unless concurrent disease /immunocompromised
Post infection -anaemia develops in 2-34 days
Bacteremia and anaemia can last for weeks
Cyclic/fluctuating numbers of bacteria
Antibiotic therapy may control acute infection but won’t clear infection
Recovered cats develop carrier status
Low grade intermittent bacteremia with no anaemia or develop milder disease when stressed.
Clinical Signs :
M. haemofelis can cause variable, but often severe anemia
Weakness, lethargy, pale mucous membranes
Intermittent fever
Tachycardia, tachypnea, haemic murmurs, depression, collapse
Clinical Pathology Results:
Regenerative anemia *
Macrocytic and hypochromic anemia
Increased reticulocytes (and may have nucleated red cells)
+/- mild hyperbilirubinemia (haemolysis)
Primarily extravascular haemolysis
Coombs +ve and autoagglutination (production of Ab against
erythrocytes)
* Anemia may not be regenerative
1. Pre-regenerative anemia
Bone marrow response takes 3-5 days to produce peak response
2. Immunocompromised patient/concurrent disease (e.g. FeLV)
Impairs a normal bone marrow response
PCR positive with non-regenerative, needs further investigation.
diagnosis:
Evaluation of fresh blood smear
tiny rod, cocci or rings on the surface of erythrocytes
In aged blood samples (e.g less day old), fall off erythrocytes
low sensitivity test
Need to distinguish between stain precipitate,
Howell Jolly bodies, basophilic stippling
Fastidious and non-culturable
Gold standard is PCR detection in blood (detecting DNA from the bacteria)
May get false negative if low numbers (decline in parasitemia,
chronic carrier phase)
Babesia Canis
Emerging Tick borne disease
Endemic in South and Central Europe
Cases of infected non-travelled dogs, Babesia found in local tick population.
Various tick sp. Dermacentor reticulatus, Riphicephalus)
Restricted geography
West Wales, South Devon, Essex.
Different sp with varying pathogenicity, B. canis of concern in UK
Can have co-infections with other TBD ( Ehrlichia, Borrelia, hepatozoon(imported dogs))
Tick infect blood with sporozoites during feeding
Sporozoites invade RBC, differentiate into merozoites, divide by binary fission, rupture RBC, infect neighbouring RBC
clinical signs-
Variable clinical signs and presentations
Mild to moderate disease and chronic carrier status can develop
Complicated forms of disease
Immunological syndromes
Primary feature is haemolytic anaemia
Haemolytic anemia, mild to severe (often severe with B. canis)
Fever, lethargy, anorexia, jaundice, vomiting, haemoglobin
Regenerative anemia
Extravascular /intravascular destruction
Intravascular destruction leads to haemoglobinuria and haemolysed plasma/serum
Can be associated with development of autoantibodies (immune mediated component)
Can have spherocytes and Coombs + result
Often thrombocytopenia (and neutropenia)
diagnoisis-Blood smear evaluation
Low sensitivity method
Intraerythrocytic
Large paired piriform organisms
Can be singular
Other Babesia sp, can be ring shaped
Canine Hepatozoonosis
Emerging disease (imported dogs)
Rhipicephalus ticks (endemic Mediterranean basin)
Unlikely to become endemic in UK, screen imported dogs.
Ingestion of infected tick, sporozoites penetrate intestinal
epithelium
Disseminate to the haemolymphatic system, undergo replication
Releasing merozoites that infect neutrophils.
clinicla signs-
Clinical signs related to the severity of parasitemia
Low burdens may be asymptomatic/mild
Higher parasite burdens - can have severe clinical signs
Infected neutrophils have reduced bacteriocidal activity - risk of secondary infections
Non-specific clinical signs - fever, lethargy, weight loss, chronic infections
Hyperglobulinemia (from infections/chronic inflammation)
Hypoalbuminemia (negative acute phase protein)
Non-regenerative anaemia (anaemia of inflammatory disease)
Neutrophilia
diagnosis-
Blood smear evaluation
Elliptical to pale blue gamonts
% of infection can vary, may be infected with no peripheral
gamonts, especially in asymptomatic/mild cases
Buffy coat smear
(Similar as above but increases the number of neutrophils
evaluated)
PCR
most sensitive method of detection
Heartworm
Present in Europe/Americas, screen imported dogs
Mosquito vector
Nemotode - Dirofilaria immitis,
Dogs are definitive host (patent infections), cats are non-definitive hosts
Three phases of life cycle:
Microfilaria (blood)
Larve (mosquito and tissue)
Adult worm (pulmonary artery or in heavy burdens right atrium)
clinicla signs in dogs-
mild- aysymptomatoic or cought
moderate- cough, exersise intolerance, abnomal lung sounds
severe- cough, exersise intolerance, abnomal lung and heart sounds, enlarged liver, syncope, ascites, death
caval syndrome- severe acute lethargy weaknesss, hemoglobinema, heamoglobinuria
diagnosis/ detection-
Features that affect detection
Long life cycle - takes up to 7 months post infection before patent adults in PA
Need to test after 7 month last possible exposure
Only mature adults produce MF - occult infection of adults but no MF
Need to know patient is Heartworm free before treating with microfilarial drugs (ivermectin / moxidectin) in case reaction to dying MF
Animals infected with Heartworm require lengthy treatment protocol that will involve 6-8 weeks of STRICT cage restriction. Prevention is better than cure.
Two types of screening tests
1. Detection of antigen
Antigen (protein secreted by the mature adult female)
Specificity good
Sensitivity good and will detect most occult infections but….
Low adult female worm burdens may yield false negatives.
Male only infections will yield false negatives
Consider a negative result ‘not detected’
All positive results MUST to be confirmed prior to treatment- with a different antigen test, MF, cardiac ultrasound/radiographs etc.
2. Microfilarial test (modified Knott Test)
1ml EDTA blood: 9ml 2% formalin
Mix and centrifuge
Remove supernatant, put sediment on slide with coverslip
Evaluate at low power under microscope
Positive tests
Validate positive antigen tests
Indicate dog is a reservoir of infection
Warning that high MF burden may react to microfilaricides
American Heart worm society recommendations
Dogs should be tested with BOTH antigen and Knotts test
Positive antigen tests need confirmation before treatment
Cats are not definitive hosts, greater resistance against
Generally have low worm burdens - males >females (1-2 worms, often single sex)
Seldom circulating microfilaria
Clinical signs - generally associated with respiratory signs but can be asymptomatic
Rarely severe dyspnoea, tachypnoea, collapse
Testing is not reliable in cats
Antigen testing (but a negative does not exclude infection)
+ Radiographs, echocardiography
Bovine Babesiosis
Red Water fever / Piroplasmosis
High prevalence in SW England
Difference sp. but B. divergens and B.major (transmitted by Ixodes ricinus) occurs in UK.
Small Babesia sp.
Merozoites invade the erythrocytes, multiply, burst out destroying erythrocyte
Cause of significant intravascular haemolytic anaemia
Disease may be mild to severe, may be less severe in endemic regions if have immunity
Severe clinical signs relate to the severity of haemolysis (can result in death)
Fever, depression, icterus, anorexia, tachycardia, tachypnea, pale mucous membranes, haemoglobinuria
Other signs could include reduced fertility/production/abortion.
diagnosis-
Clinical signs/pigmenturia/local knowledge/changes in pasture etc
Fresh blood smear evaluation
Single or paired round oval or pear shaped structures
Low sensitivity
PCR
Bovine Anaplasmosis
A. Phagocytophilium - cause of Tick-borne fever
Ixodes ricinus
Obligate intracellular bacteria - unusual residence in neutrophils
Causes disease via immunosuppression
Reduced number of cells
Reduced bacteriocidal function
Affects lymphocyte signalling/function
Infection on its own usually causes self limiting febrile disease
Can also cause abortion, mild drop
Increases susceptibility to other diseases (pasteurellosis, septicaemia)
Causes persistent infection/carrier status -
evades detection (changes surface proteins)
Status can last up to 2 years
Presence of bacteremia at various time points
Peak bacteremia >50% granulocyte infected.
diagnosis-
Blood smear evaluation (but low sensitivity)
Mulberry like micro-colonies (morulae) of coccobacciliary bacteria
Size 0.2-05 um diameter
Within cytoplasmic bound vacuoles
PCR (pan-Piroplasmosis PCR for Babesia and Anaplasma, APHA)
Serology (IFA, ELISA) (not routinely used )
Equine Piroplasmosis
Disease of concern
Protozoa: Theileria equi (formerly Babesia equi) Babesia caballi
Endemic in tropical and subtropical regions
Tick borne disease - multiple tick vectors inc. Dermacentor reticularis
Intra-erythrocytic disease
Replicates in RBC, ruptures cells, merozoites released into the circulation, infects further RBC
clinical signs-
Both sp. induce similar disease, cannot be distinguished clinically
Different forms of disease acute, sub-acute, chronic
Acute
Haemolytic anaemia (varying severity, can be severe)
Icterus
Haemoglobinuria (severe cases)
Thrombocytopenia (destruction or consumption)
Fever, inappetence, oedema (occasionally death)
Chronic/carrier states
Mild variable and non-specific signs
Clinically indistinguishable from chronic inflammatory diseases
Variable anaemia, lethargy, anorexia, weight loss, reduced performance and fertility, may be asymptomatic
Still pose a reservoir for tick borne and iatrogenic transmission
Not reportable or notifiable in UK
No formal UK requirements for pre-import screening
Asymptomatic horse could enter UK and seropositive horses are present in UK (2016 study reported 8% seropositivity of pre-export submissions!)
Exposure to Dermacentor tick - could theoretically establish/transmit disease
Iatrogenic transmission possible
Can treat (imidiocarb) but T. Equi
generally considered life long disease
Serology tests (3 methods of antibody detection commercially available)
cELISA- considered better test for detecting chronic infection
CFT - more likely to detect acute infection
IFT
PCR - false negatives occur
No test is perfect and a combination of serologic tests may be required (especially if suspicion of clinical disease).
USA, Australia and Japan are disease free and require pre-import testing
USDA recognises the cELISA as approved screening test
Camelid Mycoplasma
Candidatus Mycoplasma haemolamae
Transmission unknown but suspected to be ticks?
MANY infections are subclinical
Above study; herd 131 llamas, 29% prevalence (PCR +ve) but no evidence on blood smear,
healthy, non-anaemic population
represents sub-clinical infection
only one case developed clinical signs of anaemia (but had focus of inflammation)
Mycoplasma haemolamae - potential cause of regenerative anaemia
M. haemolamae secondary cause/associated with chronic disease
GIT parasites (Haemonchus) most common cause of anaemia
Higher GIT parasitemia more likely to be severe anaemia
Haemonchus and M. Haemolamae together cause more severe anaemia
diagnosis-
RBC small and elliptoid
Lots of small blue dots on surface of RBC
Identify on blood smear (make fresh as organisms will fall off)
PCR
Positive result interpreted in context of clinical signs
Is there anaemia?
FEC, other disease
cachexia
weakness and wasting of the body due to severe chronic illness
psuedomelanosis
post mortem change
green blue staining by FeS
FeS is formed by H2S from putrefactive bacteria and iron from HB from lysed red blood cells
will progress to black colouration under the right circumstances
chilling a carcuss will often effect the cornea and or lense of the eye. how?
it will increase the opacity
haemoglobin inhibition
the red discolouration of tissue due to haem from lysed erythrocytes
commonly seen as a freeze thaw artifact
can also happen over time, esspecially in organs that contain a lot of blood like the heart
Antemortem
Occurred to the animal before it died
Incidental findings
True lesions
Agonal
Occur at the time of death
Lung and liver congestion
Artefact
Occur as part of killing the animal
Barbiturate crystals in heart
Splenic congestion due to barbiturate euthanasia
Gun shot damage to head
Freeze-thaw/chilling artefact
Post mortem change
Occurs after the animal is dead
Rigor mortis
Algor mortis
Livor mortis/hypostatic congestion
Pseudomelanosis
Putrefaction
Haemoglobin imbibition
Autolysis
blood cyst
Focally raising the contour of the atrial surface of the mitral valve is a single, smooth red, round focus, measuring approximately 3mm in diameter
Interpretation: blood cyst
Seen frequently in young ruminants
Incidental
endocardiosis
Multifocally at the line of closure of the mitral valve the valve is thickened and pale cream with raised coalescent nodules.
Age-related change commonly seen in older dogs
must be interepreted in context
How is this different to mitral valve disease?- vegitative lesions. not smooth.
Bronchial Mineralization
incidental finding
Difficult to see grossly but can sometimes in older dogs’ lungs, feel multifocal firm to gritty small areas within the parenchyma
Age-related incidental calcification
If widespread the main differential would be uraemic mineralisation/calcification due to renal failure of vitamin D poisoning
Paralaphestrongylus tenuis
incidental finding
Description: Multifocally within the meninges and over the surface of the dorsal cerebrum are multiple nematodes
Interpretation: Paralaphestrongylus tenuis
Non-pathogenic parasite of the white tailed deer (USA)
Incidental in definitive host (white tail deer), causes neurologic disease in a number of aberrant ruminant hosts.
Multifocally within the meninges and over the surface of the dorsal cerebrum are multiple nematodes
Paralaphestrongylus tenuis
Non-pathogenic parasite of the white tailed deer (USA), therefor typically incidental in these hosts
Incidental in definitive host, causes neurologic disease in a number of aberrant ruminant, camelid and equine hosts.
Ascarid migration
incidental finding
Description: Multifocally affecting all lobes of the liver are poorly-demarcated, flat, vaguely round, white to pale tan foci
Interpretation: Ascarid migration
Various species
Hepatocellular adenoma/carcinoma
possible incidental finding
Description: Entirely obliterating the left lateral lobe of the lever is a large nodular vaguely round pink to red firm mass
Interpretation/morphological diagnosis: Hepatocellular adenoma/carcinoma
history important
Only an issue if they rupture, can grow quite large in old dogs completely un-noticed
However, a small proportion will produce insulin-like peptides or IGF-2
-> hypoglycaemia
Nodular hyperplasia
posiible incidental finding
Description: Focally expanding the parenchyma and raising the contour of the spleen is a focal, well-demarcated, black to red to pink mass
Interpretation/morphological diagnosis: Nodular hyperplasia
Can grow large, can rupture
There are however lots of malignant neoplasms that can form masses in the spleen-
Haemangiosarcoma
Lymphoma
Histiocytic sarcoma
siderotic plaques
possibel incidental finding
Description: Focally extensively raising the capsule of the lateral aspect of the body of the spleen are raised cream to white to grey gritty multifocal to coalescing (squishing toghtther) plaques
Interpretation: siderotic plaques
Accumulations of debris associated with erythrocyte turnover.
Histopathologically are quite pretty with multiple variations of metabolised haem-
Haemosiderin
Hemotoidin - Gamna-Gandy bodies
Renal cysts
Renal cysts
Can be incidental
Can also be pathological
Quantifying and contextualising is important
can be common finding in slaughter pigs but alco couldy be pkd
bird erythrocytes
Nucleated
Larger than mammals’ smaller than reptiles’
Elliptical cells
Elliptical, central nucleus
Higher oxygen demand so higher than mammals
Normal PCV 35-55%
RBC Life span 28-35 days
Lower red cell mass in juveniles
Few significant gender influences
1-5% Polychromasia
Higher % in juvenile birds
Generally as a result of haemorrhage
Toxicosis another common cause
reptile erythrocytes
Nucleated
Larger cells than birds and mammals
Blunt ended ellipse
Central round/ovoid nucleus with Irregular margin
Lower oxygen demand so lower PCV
Normal PCV 20-40%
RBC life span 600-800 days!
Influence of gender, hibernation, environment – lots of variation
May have mitotic figures in RBCs
May see increased regeneration
With blood loss or without blood loss
mammal erythrocytes
Anucleated (No nucleus)
Anisocytosis/Polychromasia common in some species
Shorter half life c/f dogs and cats
Rodent and rabbit RBCs shorter half life c/f cats/dogs (45-68 days)
PCV varies a little with species (Rabbits 30-50%)
Can see high levels of regeneration
Esp juveniles
Non regenerative anaemia - reptiles
Most common form of anaemia in reptiles
Systemic disease
Starvation
Chronic disease
GI disease
Neoplasia
Suboptimal Husbandry
Non regenerative anaemia - Birds
Systemic disease
Starvation
Chronic disease
Neoplasia
Drugs
Suboptimal Husbandry
Many infectious diseases
- spergillosis, Chlamydiosis, TB, circovirus, chronic bacterial infection
Leukocytes in Exotics
Granulocytes
Lymphocytes
Monoocytes
Azuropohils (snakes)
Heterophils/Neutrophils
Functionally the same
Different staining
Most mammals have neutrophils
Rabbits and some rodents – heterophils
Reptiles, Birds – heterophils
Most common leukocyte to vary in disease
Predominant leukocyte usually- Some species lymphocytic
Rabbits, G. Pigs, mice, rats, gerbils
Heterophil:lymphocyte ratio
Function & Appearance of Heterophils/Neutrophils
Phagocytosis and lysosomal action
Irregularly round cell
Granules
Often rod shaped granules esp in birds
Granules often fused together
Basophilic nucleus
Lobed - 2-3 lobes in birds
Non lobed oval nucleus in reptiles
Very variable appearance in
reptiles
Heterophilia
Stress (transport, restraint, fear, crowding, management, trauma, temperature stress, anaesthesia)
Infectious causes, inflammation
Neoplasia
Necrosis
Differentiate between physiological and pathological heterophilia
Left shift (increased band heterophils)
Less lobed nucleus
More basophilic (bluer), fewer granules
Toxic Changes (main marker in reptiles)
NB reptiles huge variation
Biochemistry changes (Fibrinogen assays, A:G ratios, acute
phase proteins
Pseudoheteropaenia
True Hetero/Neutropaenia
Sepsis
Viral infections
Myelosuppression
Iatrogenic/drugs
Neoplasia)
Combined with left shift in severe consumption in overwhelming infection
NB in Lymphocytic species, heterophil:ymphocyte ratio more reliable
Eosinophils in exotics
Exact function unknown in some species
Loosely foreign antigen
Larger than heterophils with round outline
Red/orange round cytoplasmic granules
Some species have pale blue granules eg AGP/iguanas
Birds – bilobed nucleus
Reptiles – elongated/round nucleus
Generally in fewer numbers
Raptors higher eosinophils <15%
Reptiles variable
Eosinophilia/ Eosinopaenia in exotics
Eosinopaenia
Typically low numbers so eosinopaenia hard to identify/define
Stress
Glucocorticoids
Eosinophilia
Less clearly defined than in dogs/cats where usually parasites
Artefactual
Foreign Antigen
Marked tissue trauma
Parasites
Rarely hypersensitivity
Azurophils
Slightly smaller than the monocyte
Non segmented nucleus
Darker more basophilic cytoplasm than monocyte
Prominent red cytoplasmic granules
Appearance and function more similar to neutrophils
Can be <35%
Increase with acute inflammation or bacterial infection (similar to neutrophils) but do also have heterophils
No real clinical benefit in differentiating from monocytes
Thrombocytes in birds and reptiles
Nucleated cells
Second most numerous cell in peripheral blood
Small, round to oval cells
Round to oval nucleus
High Nucleus:Cytoplasm ratio
May contain eosinophilic granules 1 or 2 in one area of the cytoplasm
Clump or form aggregates in blood films
Avian thrombocytes capable of phagocytosis
Thrombocytopaenia
Decreased BM production
Excessive peripheral utilisation
Chronic inflammatory conditions
Severe septicaemia
Thrombocytosis
Chronic inflammation
Haemoparasites in exotics
Protozoan Haemoparasites
Insect vectors (leeches in aquatic reptiles)
Haemolytic anaemia
Haemoproteus
Plasmodium
Leukocytozoon
Trypanosomes
Microfilaria of filarial nematodes
Avian Biochemistry
Rarely provide definitive diagnosis
Significant variation with species, age, gender, lifestage
Liver and Muscle
AST & Bile Acids most sensitive indicators of liver disease
AST not liver specific – can be elevated with muscle damage, inflammation, sepsis
GLDH most specific marker oof hepatocellular damage
Bile acids reliable indicator of liver function (must collect serum as heparin affects it)
Post prandial bile acid elevation so fasted samples preferredCK elevation with muscle damage so should be used alongside AST and GLDH to differentiate
ALT, ALP & GGT very non specific
Bilirubin concentrations inconsistent in liver disease and across species
Biliverdin primary bile pigment
Renal
Uric acid most reliable test of renal disease (NB affected by many factors)
Dehydration and renal disease can both elevate uric acid
Can be used as prognostic indicator for gout (>600uml can lead to precipitation in joints)
Urea and creatinine not useful for renal disease
Creatinine not synthesised by birds (Creatine instead)
Urea can be useful for assessing hydration status (but 10-15 x increase not uncommon)
Other
Protein levels lower in birds c/f mammals
Glucose levels more stable in birds as not utilised by RBCs but see stress and postprandial↑
BG ranges in birds higher than mamamls
Calcium – consider total and ionised calcium
Egg laying biochemistry
Reptilian Biochemistry
Lymph dilution common and will reduce all biochemical values
Effects of sex, season profound
Liver and muscle
ALT, ALP, LDH non specific
AST found in liver, kidneys & muscle so should be assessed alongside CK and LDH
GGT in liver and kidneys; sensitive for hepatic & renal disease
GDH may be useful indicator of hepatocellular necrosis
Biliverdin is primary bile pigment – no assay commercially available
Bile acids vary across reptilian taxa
Renal
Uric acid main excretory product of protein metabolism – produced in the liver (gout)
Fasted samples required in carnivorous reptiles
Uric acid main excretory product of protein metabolism – produced in the liver
Fasted samples required in carnivorous reptiles – postprandial elevations
Uric acid marker of renal disease, dehydration
Persistent elevations can –> visceral & articular gout
Reduced uric acid levels seen in hepatic disease
Urea and creatinine less useful as low and variable levels
May see elevated urea levels in early rehydration as can be resorbed across bladder wall
Ca:P ratio one of most useful indicators of renal disease
Sodium ↑ with dietary intake and dehydration and ↓ with renal disease, GI losses
Other
Calcium – egg laying females
Exotic Mammal Biochemistry
Variations between carnivores & herbivorous species
Liver & Muscle
ALT elevations seen with hepatocellular damage so can be useful initial screening parameter
AST found min muscle and liver so should be interpreted alongside SK
ALP non specific for liver, elevated in young, growing animals or high bone turnover
Calcium
Rabbits unique amongst mammals in their Ca absorption mechanism
Dietary intake can cause hypercalcaemia
Renal
Urea elevations as per other mammals with dehydration, renal disease, obstruction
Can see hyper or hypcalcaemia
Other
Hepatic lipidosis elevated trigycerides & cholesterol
exotic haemotology: Metabolic bone disease & Hypocalcaemia
Calcium leached out of bones
Calcium and Vit D intake +/- UV exposure
Must measure iCa as well as Total Ca
Hypocalcaemia in African Grey Parrots
Often collapse, seizures. Tremors
iCa diagnostic
Further lectures to cover this in more detail
Egg Laying Biochemistry
Female birds and reptiles
Classic pattern of biochemistry
Constituents of egg and shell mobilised
↑ Total Protein, Globulin, Uric Acid, ALP, Total Calcium
Check ionised calcium
Comparative pathology
Comparing human disease with that of animal models
Animal models can be spontaneous or induced
Spontaneous models in inbred mice are some of the most well known and technically simple
The NOD (non-obese diabetic) mouse was discovered and established in Japan and is model for human type 1 diabetes mellitus.
Induced can be chemical or genetic
Streptozotocin given to rats is toxic to pancreatic beta cells, resulting in type 1 diabetes mellitus
Genetic involves knock-in, knock out or transgenic
mouse knock-in model generated to upregulate HER2, or the mouse orthologue Erbb2, in breast cancer
comparitive pathology Models of atherosclerosis
Refers to a type of arteriosclerosis (narrowing of vessels)- Composed of lipid, fibrous tissue, and calcium deposits in vessel walls
Hugely important in human medicine and one of the major causes of coronary heart diseases (heart attack)
Rare in animals
Dogs
Secondary to hypothyroidism, diabetes mellitus, and dogs with breed-related hyperlipidemia (Miniature Schnauzers)
A recent study identified gonads of dogs as common locations for atherosclerosis, +/- amyloid deposits, associated with age and interstitial cell tumours (Ushio et al, Vet Pathol, 2021)
Rabbits
Chickens
Pigs
Nonhuman primates (NHPs)
Rabbits are the most commonly used research species- Three types of rabbit model are commonly used for the study of human atherosclerosis and lipid metabolism: (Fan et al, Pharmacology & therapeutics,2015)-
Cholesterol-fed rabbits
Watanabe heritable hyperlipidemic rabbits, analogous to human familial hypercholesterolemia due to genetic deficiency of LDL receptors,
Genetically modified (transgenic and knock-out) rabbits
comparitive pathology Hamster models of COVID-19
In contrast to other rodents, hamsters are naturally susceptible to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
As soon as angiotensin converting enzyme-2 (ACE2) was discovered as the principle human cellular receptor for the viral spike (S)-protein, systematic structural protein analyses of mammalian ACE2 homologs predicted that macaques, mink, ferrets, common marmosets, felines, rabbits, hamsters, and few other mammals but not mice would be naturally susceptible to the infection
The Syrian hamster (Mesocricetus auratus) rapidly developed into a popular model. - It recapitulates many characteristic features as seen in patients with a moderate, self-limiting course of the disease such as respiratory tract inflammation and age dependence.
Had already served as a model for SARS-CoV infection in 2005
The Roborovski dwarf hamster (Phodopus roborovskii) more closely mimics the disease in highly susceptible patients with frequent lethal outcome, including devastating diffuse alveolar damage and coagulopathy
comparative pathology Models of Duchenne muscular dystrophy
Duchenne muscular dystrophy (DMD) is a progressive, fatal, X-linked monogenic muscle disorder
Results in progressive muscle wasting. Caused by mutations in DMD, a gene encoding the protein called dystrophin
In order to test treatments for DMD, a range of natural and engineered animal models have been developed, including mice, rats, rabbits, dogs, pigs.- There appears to be an effect of body size in models of DMD, as the severity of the clinical signs increases with increasing body size across species.
All DMD models have different advantages and disadvantages
The best known model is the dystrophic mdx mouse- 2800 papers published using this mouse
Good biochemical model of DMD
But, the mice have only a slightly shortened life span and show no obvious clinical signs of muscular dystrophy
A number of different breeds of dogs presented at veterinary clinics have been diagnosed with dystrophin-deficient muscular dystrophy.- Several of these have been subsequently used to develop dog models of DMD
The most common being a Golden Retriever with Muscular Dystrophy (GRMD)
While these dogs do show clear clinical signs analogous with DMD, there are some significant differences. A number of the GRMD dogs die within the first 6 months of life and there is considerable dog-to-dog variation, which, with the small numbers available for each experimental group, makes it difficult to show clear statistically significant results
The rabbit model is a recent creation using CRISPR/Cas9- Rabbits have the advantage of being easier to breed and less costly than dog or pig models, but have clear clinical signs, in contrast to many mouse models.
outline the drug developmet process
identify the target- understand the disease
validate the target- show that the target is clinically relevant
ADME- Pharmacokinetics of agent
Toxicity- is organ damage caused by agent?
tolerabiluty- advere effects of behavioural agent?
pharmacodynamic effect in target organ- agent engages target and causes clinically measurable effect
Humanized mice
= immunodeficient mice engrafted with functional human cells and tissues
It all started with the SCID mouse- Commonly known as the nude mouse
Athymic due to a loss of function mutation in the PRKDC gene
Resulting in impaired development of T and B lymphocytes which gives rise to severe combined immunodeficiency (SCID).
The most common approach is to engraft human CD34+ hematopoietic stem cells which migrate to the bone marrow of the mouse and differentiate to all lineages of the mature immune system
Some models involve whole body irradiation prior to engraftment
Patient-derived xenografts in humanized mice- Not a new idea injecting human tissue into mice
Orthotopic models involve implanting a human tumour into the corresponding tissue in animal models.- E.g. breast cancer cells directly into mammary tissue in mice
Using a humanized mouse for this more appropriately models the tumour microenvironment, the contribution of the immune system to the eradication of tumour cells, and could predict drug response
Veterinary diagnostics enable us to …
Establish a diagnosis
Provide prognostic information
Guide selection of treatment or control strategies
Monitor effect of treatments
Veterinary molecular diagnostics
Amplify the genome of viruses present in or released from infected cells
DNA of bacteria, fungi or parasites
Polymerase chain reaction (PCR)
denaturing, anealing, extention
Uses oligonucleotide primers to amplify region of interest (gene)- for specific antigen, toxin ect
Cycles of heating and cooling drives each step
Millions of copies can be produced in minutes
Number of copies provides information on presence and/or amount of starting material
PCR - denaturation
High temperature breaks hydrogen bonds holding base pairs together- 94ish
‘Melts’ double-stranded DNA revealing bases in specific order
PCR - annealing
At cooler temperatures, complementary bases can bind- 50ish
Oligonucleotide primers ‘match’ small regions of the target area (gene of interest)
They bind to the matching areas (anneal)
Primers must be designed so that one matches the sense strand and the other matches the antisense strand
PCR – extension/elongation
Temperature raised to approximately 74°C
Synthesis of new complementary DNA strand from 3’ end of primer
Only regions where primers bound will be amplified/copied. So it’s really important that they only match the region we’re interested in
PCR – cycling
In one cycle (denaturation; annealing; extension) we have gone from one copy to two
Cycle is repeated multiple times and product number increases exponentially
Average PCR run is 40 cycles
Semi-quantitative PCR
The amount and size of the PCR product can be visualised using staining and gel electrophoresis
This visually confirms if our pathogen / gene of interest / strain is present
Known as semi-quantitative PCR
Quantitative PCR (qPCR)
the amount of DNA amplified in each cycle are quantified.
increased florecence indicates increased presesnce of target
targrt floreced via cyber green or Taqman
TaqMan more specific- floreces when “knocked off” target stran d of dna by formation on new strand
cQ value
This value tells how many cycles it took to detect a real signal from your samples.
the point in qPCR where a flourecent signal is detectable
Reverse transcriptase PCR (RT-PCR)
Uses reverse-transcriptase enzyme to produce double stranded DNA from RNA
This provides template for normal PCR
Can also be incorporated into qPCR = RT-qPCR
PCR for viral infections
very useful
Serological assays are not always feasible when detecting viral infections so PCR can be used
Lack of species-specific secondary antibodies
Suitable cells for growth and titration are not available
primer needs to be developed
methods for molecular diagnostics of bacteria
Culture- labour intensive, can take long time, contamination of culture common, multiple plates and culture mediums may need to be used
Stain
Test
not useful for, for example:
Helicobacter-
Many different species that can infect veterinary species- which one do u culture? which one is actually casing disease
Individuals can be infected with more than one species at the same time
Fastidious bacteria (difficult to culture)
Helicobacter
Many different species that can infect veterinary species
Individuals can be infected with more than one species at the same time
Fastidious bacteria (difficult to culture)
PCR primers designed to detect a single species
Rapid test
diagnostic methods for Fungal infections
Slow growth in culture
Diagnosed histologically
Can be diagnosed with PCR
PCR can be used if no identifiable fungal species cultured or morphologically identifiable
Pathogen-specific primers
Generic fungal primers (e.g. rRNA)
Genus-specific primers
Benefits of PCR
Specificity is very high- primers can be designed to be incredibly specific
Sensitivity is very high- you cna have very little dna and it will work (some assays are still more sensitive though- giardia assay duse to fecal sample having pcr inhibitors
Rapid turnaround time
Overcomes culturing restrictions
Negatives of PCR
PPV can be low
Not for all assays/samples
Requires specialist equipment
Overcomes culturing restrictions
Positive predictive value (PPV)
The probability that a test positive animal is diseased
Disease agents may colonise healthy animals as well
PCR detects DNA/RNA in live and dead organisms
May be positive even if infection is controlled or cleared
Interpretation of results for a single animal can be difficult
PCR inhibitors
False negatives present a challenge
Often occur due to PCR inhibitors in the sample
Natural inhibitors include:
Bile salts
Polysaccharides in faeces
Haem from blood
Glycogen and fats in tissues
Proteinases in milk
Urea in urine
to combat this there are:
Co-purified with DNA/RNA
Extraction kits designed to remove them
Organism vs antibody detection
Detection of organisms gives most information
Assays not always available or optimal
Antibody detection still commonly used
Combinatory approach can be used
PCR positive result can occur prior to seroconversion – prove infection in acute cases
PCR can be negative later in course of disease
Serum antibodies are detectable
Serology
Detect antibodies or antigen in blood sample
Indirect method
Limitations due to lack of species-specific secondary antibodies
Seropositivity may not indicate acute infection
Antigen:
Specific portion of pathogen
Protein found on surface of pathogen
Non-self
Antibody:
Proteins (immunoglobulins (Ig))
Part of the immune system (self)
Created to bind to specific antigens
Specific antigen binding sites
The most common antibodies have 2 binding sites, some have 4 or 10
Binds to antigen
Neutralises antigen
ELISA - Enzyme Linked Immunosorbent Assays
2 types of ELISA:
Direct test - Antibodies used to test for antigen
Indirect test – Antigens used to test for antibody
Can test for:
Bacteria or bacterial toxins
Viruses
Protozoa
Ab to any of these or Ab to parasites, yeasts,
Direct test ELISA
Antibodies used to test for antigen
Sample proteins immobilised on plate/well
Enzyme labelled antibodies added
Antibodies bind to antigen
Enzyme-specific substrate added
Reaction takes place and produces colour
Colour change (signal intensity) detected
indirect test ELISA
Antigens used to test for antibody
Indirect ELISA
Detection of antibody:
Antigen immobilised on plate/well
Sample is added
Any antibodies present will bind to antigen
Enzyme-labelled secondary antibody added
Substrate added
Reaction takes place and produces colour
Colour change (signal intensity) detected
Sandwich ELISA
Detection of antigen:
Plate/well coated with capture antibodies
Sample is added
Any antigen present will bind to antibody
Direct: enzyme-labelled antibody used
Indirect: Enzyme-labelled secondary antibody added
Substrate added
Reaction takes place and produces colour
Colour change (signal intensity) detected
Competitive ELISA
multiple ways to set up depending on whether the antigen or antibody is of interest
Detection of antigen or antibody:
Sample antigen/antibody competes with reference antigen/antibody
Analyte concentration is indicated by signal interference
Coat plate with reference antigen
Incubate sample (unknown antigen concentration) with limited amount of labelled antibodies
Low antigen conc. in sample = large portion of labelled antibodies have nothing to bind to
Add this mixture to the antigen coated plate
Any free labelled antibodies will bind to reference antigen
Wash plate to remove antibodies bound to sample antigen
Add substrate
Stronger colour = less antigen present in sample
ELISA – important steps
Plate coating: Samples are diluted in buffer, then pipetted into a microwell plate. After incubation, the solution is discarded and plate is washed with a wash buffer. ONLY immobilised antigen/antibody remains
Plate blocking: Blocking buffer is added to the plate. This binds to any remaining protein-binding sites in the coated wells, reducing non-specific binding of antibodies to the plate. Plate then washed again
Antibody incubation: Following incubation, wash away unbound antibodies with a wash buffer.
Detection: The enzymes covalently attached to the antibodies will start producing a coloured reaction product. Stop solution is added to terminate the colour development and the absorbance of each well is read. The signal intensity allows you to determine whether a sample contains the antigen/antibody of interest, and at what concentration. By stopping all wells at the same time (with stop solution) the signal intensity if indicative of the antigen (or antibody) concentration.
signla detection in a Lateral flow immunochromatographic assay
ELISA
Detect the presence of a target substance (antigen) in a liquid sample
‘Signal’ is still a colour change
But does not require specialised equipment (patient-side)
Chromatography paper = capillary action
Antigen binds to antibodies with tag
Flow along test paper
Collect at test line – fixed antibodies that will bind to antigen(Collection = visible line)
Flows across control line – fixed antibodies that bind to tagged antibodies
Detection of signal indicates detection of antigen-antibody complex
Epithelial cells
All endoderm and some ectoderm
Cells form bulk of parenchyma of organ, glands or line organs
Hepatocytes
Skin
GIT
Bladder
Cell-to-cell and cell-to-basement membrane adherence
Mesenchymal cells
Mesoderm
Supporting cells
Fibroblasts -> collagen
Endothelia
Bone
Round cells
Mesoderm
Cells of the haemo-lympho system
Erythrocytes
Leukocytes
Histological appearance of epithelia
Polygonal
Poorly-defined cell borders
Abundant cytoplasm
Polar to central round nuclei
Basement membrane
Histological appearance of mesenchymal cells
Fusiform/spindloid- long, stringy
Poorly-defined cell borders
Variable cytoplasm
Fusiform/spindloid nuclei
Extra cellular matrix
Histological appearance of round cells
Round
Well-defined cell borders
Individualised
Variable cytoplasm
Round to variable nuclei
Immunohistochemistry
Immunodiagnostic
Uses antibodies to detect an “antigen” in a tissue
IHC can be used to differentiate between inflammation and neoplasia
A classic example is inflammatory bowel disease versus lymphoma
In both diseases lymphocytes accumulate in the intestine
If inflammatory this is polyclonal
Multiple lymphocytes replicating
If neoplastic this is monoclonal
One cell becomes neoplastic and replicates
Antibodies made by injecting antigen of interest into an animal
Two types of antibodies
Monoclonal
Antibodies produced by the same clone of plasma B cells
Hybridisation with tumour cells
Higher specificity, lower sensitivity
Polyclonal
Heterogeneous mix of antibodies
Derived from the immune response of multiple B-cells
Each one recognizes a different epitope on the same antigen
Higher sensitivity, lower specificity
cytokeratine lables
Epithelial cells
vimentin lables
Mesenchymal cells
Indications for a kidney biopsy:
Proteinuria
Acute renal failure
Chronic renal failure
Renal azotaemia that cannot be categorized as acute or chronic renal failure
Proteinuria
the presence of abnormal quantities of protein in the urine, which may indicate damage to the kidneys.
Proteinuria is, once a urinary tract infection is ruled out, almost always due to disease of the glomerulus. Whereas low urine specific gravity, which would indicate reduced ability to concentrate urine, is typically due to disorder of the tubule.
Podocytes
The structure of the glomerular capillaries is important in determining the rate and selectivity of glomerular filtration.
The glomerular capillary wall consists of three layers:
the capillary endothelium
the basement membrane
the visceral epithelium
= podocyte
Greek pous, pod- ‘foot’
Immune-mediated glomerulonephritis
Results from the deposition of immune complexes in glomeruli
formation of antibodies against the glomerular basement membrane
activation of inflammatory cascade
Any condition that stimulates the immune system for long periods of time can cause IM-glomerulonephritis
What is cytology?
Microscopic examination of tissue samples spread onto slides
Histology looks at architecture, cytology has no architecture - look at individual cell morphology
Aspirates – solid tissue
Needle only
Intermittent suction
Continuous suction
Impression smears- mucosa, ears, biopsies
Wash / Lavage – trachea, BAL, nasal, prostate
Ultrasound guided – watch out for ultrasound / lubricant gel!
No anaesthetic and low risk of complications
Relatively quick procedure and less invasive
Rapid results – emergency cases, clients waiting, same day intervention
Older patient - removal of a benign tumour?
Grading of tumoursto he lp with surgical or chemo planning
Surgical planning
Staging of tumours
Fluid classifications – Transudate, Modified Transudate, Exudate
Infections (septic abdomen, ear cytology)
Ancillary tests-
PARR analysis and Flow Cytometry
PCR for infectious diseases
How to take a fine needle aspirate for cytology
22-gauge needle
5-10ml syringe
Glass slides
Pencil
place needle without syringe in mass- not in purilent area
rediredct needle a few times
take out needle
put air filled syringe on needle and put needle over slide
squirt cells down onto slide
suction technique-
same but pit syringe on first and apply suction while in mass
may cause haemodilution
the sample must then be spread-
Squash pull / drag method best, send both slides
Fluids-
Blood smear (push / wedge)
Line concentration
Cytospin
Pre-analytical factors for cytology
Submission forms
Formalin
Sample types used for fluid
Lubricant gel
Cellularity / Pre-staining
Preservation
Cell thickness
Greasy slides
Formalin Exposure in cytology
Exposure of unfixed cytologic specimens & air-dried unstained smears to formalin fumes → Interferes with staining
Fluid Specimens
BAL
Pleural or Abdominal fluid
Prostate wash
Urine – sediment vs. cytology- diffretn things!!!!. braf test for transitional cell carcinoma
Bile-most samples you see nothing but cats get bacterial infections
Cerebral Spinal Fluid
One or more direct preparations
Air dried and submitted with fluid
EDTA (cyto) and plain tubes (culture)
Fluid is a very poor preservative - cells deteriorate very quickly in fluid. could be done for FIP
Cellularity
The number of cells in a given tissue sample
How to assess this before sending to the lab?
Pre-staining- can effect labs staining
Assessment of unstained slides = lower the condenser
differentials for a greasy slide after a fine needle aspirate
Lipoma?
Other differentials include:
Steatitis / panniculitis
Perinodal fat
Mast cell tumour
Liposarcoma
Other soft tissue sarcoma
Not representative
Sample preparation – allow to dry and stain flat
Diff Quick – in house stain technique
Diff-Quik stain consists of:
Fixative agent - methanol, blue
Solution I - eosinophilic, orange
Solution II - basophilic, blue
Technique
Dry slides in the air
Dip slides sequentially into each solution 5 times (one second each dip)
After every immersion wait a moment to drain excess.
Rinse with tap water
Allow to dry (do not use heat sources)
Slides must be air-dried before staining – it is important to make sure the slides are very dry before staining, water may still be present when the slide appears dry – so make sure to leave sufficient time for adequate drying.
Heat fixation is not recommended as this may interfere with staining quality and can rupture cells.
When using diff quick dip slides into each solution 5 times for 1 second, followed by a water rinse and dry the slide vertically
Some tips for the ideal stain include:
If the slides are thin or have only a few cells on them - shorten staining times
Thick smears or those with high protein may need longer staining times.
Ensure stain reagents are fresh and well maintained - if your cytology slides have a lot of stain precipitate on them , it is probably time to refresh the stain.
If you get a gold film forming on the top of the stain – this means it is also time to change the reagents
Organisms in the stain may contaminate the cytological slides.
Automatic staining – external lab
may make mast cells look like histeocytoma!!!!!
MGG Quick stain – in house stain technique
new! better than diff quick
May-Grunwald Giemsa Quick stain
Performs similar to the traditional May Grunwald-Giemsa used in labs
But is quick to perform like most rapid stains
Technique
Dry slides in the air
Dip slides sequentially into each solution 5 times (one second each dip)
After every immersion wait a moment to drain excess.
Rinse with tap water
Allow to dry (do not use heat sources)
In lab automatic staining
Modified Wright’s
only material in middle of lide is stained so slides must be preped appropriatly
Modified Wright’s
Get your slides out ready
Ensure you never put any slides you have taken out of the box back in the box – avoids cross contamination
If doing needle only attach the syringe over the slides
Always start with needle only to ensure you don’t get too much blood contamination
Never package with formalin
Always submit more than one slide
Don’t put cytology slides in the fridge- erythrocytes can freeze
Avoid using a hairdryer or flame to dry- cells rupture and fragment
Greasy slides need longer to dry and should be stained flat
Make sure you use fresh stain
How to approach analysing cytology samples
Cellularity and preservation
Haemodilution
Inflammatory or Proliferative
Inflammation – infectious, immune mediated, necrosis
Proliferative type
Epithelial, Mesenchymal, Discrete / Round cell, neuroendocrine
Hyperplastic, dysplastic or neoplastic
Neoplasia – benign or malignant
Definitive diagnosis
what might be found on Haemodiluted cytology slides
Erythrocytes
Platelet Clumps
Nucleated cells in peripheral blood- are they from mass or just from the haemodilution???
neutrophils and monocytes- from blood
macrophage- from tissue
eosinophils and basophils
lymphocytes
Inflammation in cytology
White blood cells-
Neutrophils, macrophages, eosinophils, lymphocytes, mast cells (a couple are OK).
Neutrophils-
Non-degenerate neutrophils – well preserved
Degenerate neutrophils – microorganisms and necrosis.
Pale blue swollen nucleus
Macrophages-
Activated - vacuolated and foamy
Phagocytosis –fresh smear as can do this in vitro
Infectious agents (Slow growing bacteria, Fungi, Parasites
Cell debris
Erythrophagia - previous haemorrhage, breaksdown to haemosiderin and haematoidin
Reactive lymphoid hyperplasia
a benign nodular lesion, histopathologically characterized by marked proliferation of non-neoplastic, polyclonal lymphocytes forming follicles with an active germinal center.
you will see:
Mixed small, intermediate, large lymphocytes
Mott cells
Plasma cells
compare Inflammation and Infection in analysis of cytology samples
Inflammation -
Acute / suppurative - neutrophils
Chronic active / pyogranulomatous – neutrophils and macrophages
Chronic / granulomatous – macrophages (multinucleated), lymphocytes, plasma cells
Specific e.g. eosinophilic
Concurrent tissue reaction – hyperplasia / dysplasia
Infection-
Bacteria – rods / cocci / coccobacilli
Yeasts and fungi
Mycobacterium
Protozoa
Aspiration of hyperplastic lesions may show….
Higher than expected cellularity
Cells may display some mild criteria of malignancy
Mildly increased N:C ratio
Darker blue cytoplasm
More prominent nucleoli
Finer chromatin than normal
Atypical cytologic features of dysplasia:
Nuclear to cytoplasmic asynchrony
Increased cytoplasmic basophilia
Anisokaryosis and anisocytosis.
Dysplasia can be cytologically difficult to distinguish from neoplasia as dysplastic lesions often contain more criteria of malignancy than strictly hyperplastic lesions.
Types of Neoplasia
Epithelial
Mesenchymal
Round Cell
Neuroendocrine
Epithelial neoplasm
Arrangement-
Monolayer sheets, clusters, rows, palisades and acinar.
Cohesive with distinct tight junctions (desmosomes)
Clear lines between cells.
Shape
Columnar, cuboidal or polygonal
Nuclei
Round to oval.
Epithelial cells can look round in fluid or when poorly differentiated.
E.G.: Squamous cell carcinoma, adenoma and adenocarcinoma
Benign: Adenomas
Malignant: Squamous cell carcinomas
Mesenchymal neoplasms
Arrangement
Often see individual cells but occasionally seen in aggregates.
Loosely arranged with extracellular matrix and individualised spindle or stellate cells.
Shape
“Spindle cell” - spindle shaped cells, fusiform or stellate.
Wispy cytoplasmic borders, the borders are not distinct. Cytoplasm can contain vacuoles
Nuclei
Round to elliptical (oval). Cytoplasm can contain vacuoles.
Samples are often poorly cellular in benign lesions, but can be very cellular in malignancy.
Arise from connective tissue e.g.: fibroblasts, osteoblasts, adipocytes, myocytes and vascular lining cells.
E.g Osteosarcoma, Haemangiosarcomas etc.
Benign: Fibromas, lipomas
Malignant: Sarcomas, soft tissue sarcoma, haemangiosarcoma etc.
Lipoma
Greasy slides
Large fat filled adipocytes in aggregates
Often have capillaries going through them
Often benign, can have infiltrative forms
Liposarcoma - malignant version
Round Cell neoplasm
Arrangement-
Discrete and individually arranged
Shape-
Round tumour cells
Well defined / distinct cytoplasmic borders
Nuclei-
Round to oval large nucleus (can be indented)
Exfoliate well
5 main examples:
Mast cell tumour
Lymphoma / leukaemia
Histocytoma / histiocytic sarcoma
Plasma cell tumour / plasmacytoma / multiple myeloma
Transmissible venereal tumour
Mast cell tumour cytology
Round cells
Central round nuclei
Lots of magenta granules in the cytoplasm
Fibroblasts, eosinophils and ribbons of pink matrix
Lymphoma cytology
Monomorphic population of lymphocytes individually arranged
Low N:C ratio
Large cell vs. small cell lymphoma
Lymph nodes, skin, spleen, intestines
Histiocytoma cytology
Rounds cells individually arranged
Light blue cytoplasm, Nuclei round to oval to cleaved
Often accompanied by lymphocytes and plasma cells
Mass in a young dog, likely histiocytoma, although can get them in older dogs
Plasma cell tumour cytology
Rounds cells individually arranged
Looks like well differentiated plasma cells, however the cells are predominantly plasma cells. If this was reactive you would see a mix of lymphocytes and plasma cells
Prominent golgi zone
Multinucleation and Macronuclei even though commonly benign
Transmissible Venereal Tumour cytology
Used to be a rare disease in the UK
Seeing more and more cases
Sexually transmitted tumour is thought to be of histiocytic origin - transfer of intact neoplastic cells
Often around the mouth or genital region, but can be seen in other sites.
Cytoplasm is characteristic: Abundant light blue to grey with moderate to many discrete margined vacuoles
CTVT cells have 59 chromosomes compared with the normal canine karyotype of 78 chromosomes.
PCR now available to help diagnosis
. Neuroendocrine neoplasm
Arrangement-
Free nuclei arranged in small rosettes / sheets
Shape-
No cytoplasm – mostly just bare nuclei
Nuclei
Round
Exfoliate well
Examples: Thyroid tumours, pheochromocytomas
Cytology Description and Identification
Identification:
Nuclear features
Cytoplasmic features
Miscellaneous-
Background – joint fluid, product, mucous, chylous
Haemodilution – inflammatory?
Accompanying cells – contamination or tissue?
Concurrent process – haemorrhage, inflammation, necrosis
Presence / absence – e.g. lymphoid cells
When looking at a slide it is important to be systematic-
Always start at the top left of the slide.
Scan the slide at low power (4x magnification)
Assess the cellularity, background colour and then find the main cellular population
Then get closer at 40-100x
Careful to not get oil on the 40x!
it is important to appreciate certain nuclear features. Bizarre mitotic figures are often very interesting and can really help you determine whether a lesion is neoplastic. In this example here the mitotic figure is very atypical and has become fragmented. You can have multinucleate cells with different sized nuclei within the same cell. Also large prominent nucleoli are a key feature to look out for.
Nuclear features to look for in cytology
Size and shape
Chromatin
Nucleoli
Nuclear membrane
Relationship / nuclear moulding
Mitotic figures
Cytoplasmic features to look for in cytology
Vacuolation
Basophilia
Product
N:C ratio
Nuclear position
Criteria of Malignancy in cytology
Anisocytosis and Anisokaryosis
Increased nuclear to cytoplasmic ratio (not always seen e.g.: lymphocytes)
Nuclear features:
Mitotic figures, how many there are and if they are atypical
Multinucleation
Nuclear moulding
Angular nuclei
Chromatin (instead of being smooth it becomes coarse and clumped)
Nucleoli:
Prominent, multiple, angular, anisonucleoliosis
Macrocells, macrokaryosis and macronucleoli - macro is always bad news!
Necrotic cells in between neoplastic cells. These cells look like smudge cells (been rubbed out with a rubber)
Phagocytosis - cannibalism
Emperipolesis
Crowded cells
Lymphoma subtyping – Cytological criteria
Features of the abnormally represented population:
Small, intermediate or large lymphocytes
Blastic appearance (presence or absence of nucleoli)
Position of the nucleus in the cell, eccentric or central
Shape of the nucleus, round, oval, cleaved, convoluted
Relative volume of cytoplasm
Appearance of cytoplasm, eccentric, concentric, mirror-handle
Presence/absence of golgi zone
Relative numbers of mitotic figures and presence of atypical mitoses
Dimorphic lymphocyte distribution
Presence of ancillary cells, tingible body macrophages, eosinophils
Careful cytological assessment will efficiently diagnose lymphoma and allow estimation of the classification, phenotype and grade
Cells harvested for cytology are not formalinised allowing molecular and immunological investigation of stained slides
The big 5 canine lymphomas have characteristic cytological patterns recognisable to skilled cytologists, allowing a quick and cost effective diagnosis.
On cytology you can see:
Disproportionate representation of a specific lymphocyte population – In general lymph-nodes should be heterogenous, but instead in lymphoma you have a homogenous effacing population
Cytology also allows you to see very fine cellular details of the neoplastic population such as the chromatin pattern and atypical mitotic figures.
Lymphoma subtyping – ancillary tests
PARR analysis
Assessment of clonality (genotype)
Clonality Testing (PCR for antigen receptor rearrangement; PARR) uses end-point PCR to predict whether lymphocytes in a sample are a clonal or polyclonal population
Flow cytometry
Assessment of phenotype
Immunocytochemistry
Assessment of phenotype
things to avoid when taking good histeopathology samples
Don’t crush it- think about handling, dont handle critical areas, can distort tissue- lymphoid tissie and tumour cells vunerable to this
•Don’t cauterise it
•Don’t freeze it
•Don’t scrape mucosal surfaces (e.g. GIT)- rinse under water instead if needed
•Fix it ASAP!
Don’t package cytology and histology together
appropriate containers for histeopathology samples
sample pots- Label your sample pots- important! wha tis the sample!
•Use appropriate containers
•Use correct amount and type of fixative
•10:1 ratio of formalin: tissue
•10% neutral buffered formalin
dont use-
Narrow-necked bottles “pill pots”- sample may swell when fixed
Glass containers- health and saftey
Sharps container- cant open!
Different types of margins
Cross-sectional or radial
•Bread loaf or pie
Cost effective •Easy •Allows for measurement of margins •Assumes centrifugal growth from centre •Only evaluates a portion of marginal tissue
Tangential / shaved / orange peel
•Tumour bed
•Theoretically complete assessment of all marginal tissue •Technically difficult •More slides, more cost •Does NOT allow measurement of margins •Binary answer –excision complete or not
suture tags can be used to comunicate thing to pathologist
you can also ink the sample- green and blue ink best
What is heart disease vs. failure?
Heart disease is any condition affecting the cardiovascular system
- chronic in nature e.g. cardiomyopathy
- acute in nature e.g. myocarditis
- may or may not have clinical signs associated with it e.g. syncope, exercise intolerance
- abnormalities on physical examination usually present e.g. heart murmur
Heart failure is a syndrome where the heart can no longer meet the metabolic demand of the body
- Usually acute onset
- Clinical signs present e.g. exercise intolerance, syncope, lethargy, anorexia etc.
- Physical examination abnormalities present e.g. fluid thrill, dyspnoea, crackles, jugular pulsation etc.
clinical signs of heart disease
Often non-specific/ absent
Exercise intolerance and weakness
Can be syncope/ pre-syncope
Cyanosis
Coughing- left atrium can press on brochi. fluid could fill in lungs,
Paresis-condition in which muscle movement has become weakened or impaired. thrombi can be lodged in aorta. thrombi can aso cause lamness
(acute blindness, neurologic signs)
on physicla examination:
Body condition score
Respiratory rate and effort
Ascites- condition in which fluid collects in spaces within your abdomen
Distended jugular
Pulsating jugular
Peripheral oedema
Cyanosis
Right to left shunting defect from deoxygenated circulation to oxygenated
Central cyanosis
Differential cyanosis
Peripheral cyanosis
Heart murmur (dog vs cats)
Arrhythmia (dogs vs cats)- cats is assosiated with heart disease but more varied differential with dogs
Gallop sound
Cat with cold hindlimbs
Cyanosis
Presence of goitre
Retinal detachment
Some neurological signs
clinical signs of Heart failure
Tachypnoea/ dyspnoea (L CHF usually)
Weight loss (less cats)
Swollen abdomen (R CHF)
Peripheral oedema (R CHF)
Signs as per heart disease
mm often normal!!!
Dyspnoea/ tachypnoea
Crackles in lungs
Ascites (fluid thrill)
Jugular distension
Significant jugular pulsation
Muffled heart or lung sounds
Positive hepatojugular reflux
Pulsus alternans/ paradoxus
Peripheral oedema
Plus usually signs of heart disease
Jugular pulsation
Normally only 1/3 up neck
If to angle of jaw – abnormal
Arrhythmias
Tricuspid regurgitation
Pericardial disease
Jugular distension
Should collapse after pressure released
Elevated systemic venous pressure
R heart failure
Pericardial disease
Obstruction of cranial vena cava
Hypervolaemia (cats)- fluid overload, is a condition where you have too much fluid volume in your body
Thoracic examination- what to lookout for if heart disease is expected
Auscultation-
Heart – both sides thorax, apex and base
Heart murmur
Gallop sounds
Arrhythmia – Atrial fibrillation, AVB…
Heart rate – brady/tachyarrhythmias
All lung fields
Compare sides and dorsal vs. ventral
Muffled
Crackles
Palpation/ percussion/ compression-
Apex beat displaced
Thrill
Percussion for fluid/ soft tissue/ air
Reduced compressability (cats)
gallop sounds on heart auscultaion
Normally heard in dogs and cats-
Occur during systole
S1
‘lub’
Closure of AV valves
S2
‘dub’
Closure of semilunar valves
Not normally heard in dogs and cats-
Gallop sounds (occur in diastole)
S3
Early diastolic filling
Not heard in compliant ventricle
Systolic dysfunction
S4
Atrial contraction
Forceful atrial ejection into a noncompliant ventricle
Hypertrophic/ restrictive cardiomyopathy
Abdominal examination- for heart faliur
Palpation-
Fluid thrill – ascites
Splenomegaly occasionally CHF
Hepatomegaly too
Painful sometimes
Hepatojugular reflux-
Squeeze just behind ribs
Watch jugular vein
If jugular vein distends whilst squeezing – positive response
Positive response suggests high R sided filling pressure
R side can’t accommodate extra blood
Pulsus alternans
Alternates strong with weak
Myocardial failure
Pulsus paradoxus
Decrease pulse quality on inspiration
Pericardial effusion
What is a heart murmur?
Extra sound
Occur during systole (most commonly) – between ‘lub’ and ‘dub’
Or diastole – after dub
Or both (continuous murmur) – all the time
Due to regurgitation of blood e.g. mitral regurgitation
OR turbulent flow across a narrowing e.g. sub-aortic stenosis, VSD
OR reduced viscosity of blood (anaemia)
Blood flows DOWN pressure gradient
High pressure – low pressure
The greater the gradient the faster the flow
Depending also on resistance to flow
Flow ONLY occurs when a pressure difference exists
Can explain many phenomena:
PDA – continuous murmur (L-R shunting)
Murmurs on right often quieter than left
VSD shunts L-R ‘normally’
Reverse shunts tend to be quieter
Descriptive characteristics of heart murmers
Grade
1 – barely audible, need quiet room
2 – audible but quieter than heart sounds
3 – clearly audible and as loud as heart sounds
4 - louder than heart sounds
5 – THRILL (PALPATION) present- buzzing feeling of chest
6 – Audible with stethoscope lifted off chest
Mild/ moderate/ loud/ thrilling (Ljungvall 2014)
Timing
Systolic/ diastolic/ continuous
Can be further classified as holo- and pansystolic
Location
Right/ left
Apex/ base (dogs)
Sternal/ parasternal (cats)
Radiation- does it radiate dorsaly? to the left? ect
Apical systolic murmurs
Mitral regurgitation-
Grade can correlate with severity (MMVD not DCM)
Pansystolic worse (MMVD)
Can be musical/ whooping
Often radiates to right
Tricuspid regurgitation-
Difficult to distinguish from radiating left sided murmurs
Vary with respiration
Tricuspid valve dysplasia
Pulmonary hypertension
Degeneration of valve
Basilar systolic murmurs
Aortic stenosis-
Harsh sounding
Radiate widely to thoracic inlet
Low grade are difficult to distinguish from physiologic/ innocent
(Cats – HOCM dynamic)
Pulmonic stenosis-
Left heart base
Radiate dorsally
Innocent/ functional murmurs
Innocent-
Puppies and kittens
No structural heart disease
Grade 1-3
Systolic
Left heart base
Don’t radiate widely
Functional-
Associated with disease process
Anaemia
Hyperthyroidism
Fever
Hypertension
Pregnancy
No structural heart disease
Grade 1-3
Systolic
Left heart base
Don’t radiate widel
Other systolic murmurs
Ventricular septal defect (VSD)-
Usually left to right
Smaller defect louder murmur
Right sternal border
Increased right side pressure
Quieter
Bi-directional
Right to left
Absent
Atrial septal defect (ASD)-
Murmur not directly related to ASD
Only large defects
Increased blood flow
Relative pulmonic stenosis
Left heart base
Diastolic murmurs
Aortic regurgitation-
Heart base
Quiet
Endocarditis/ congenital
Early closure of MV – Austin flint murmur - severe
Pulmonic regurgitation-
Uncommon
Left base
Pulmonary hypertension
Mitral stenosis-
Rare
Left apex
Mid-diastole
Continuous (machinery) murmer
Patent ductus arteriosus (PDA)
Loudest heart base
Radiate to thoracic inlet
MISS THEM if only auscultate apical region
Other causes very rare
Differentials for heart disease
Depends on clinical sign/ physical examination finding
Respiratory disease – cyanosis, dyspnoea/ tachypnoea, muffled heart sounds, crackles, dull percussion, cough, syncope
Neoplasia – ascites, muffled heart sounds, dyspnoea/tachypnoea, dull percussion, weakness
Hypoproteinaemia – ascites, muffled heart sounds
Neurological disease – paresis, paralysis, weakness, syncope
Metabolic disease – syncope, weakness, tachypnoea
when should you be concerned with heart murmers in dogs
Symptomatic – tachypnoeic/ dyspnoeic, syncopal, exercise intolerant, cyanotic etc.
Pyrexic and new murmur
Small breed dog with grade 3/6 or louder left apical murmur (MMVD)
Breed predisposed to DCM with an apical murmur (remember Cocker spaniels too)
Intended for breeding/ athletic activity
Grade 3/6 or louder murmurs over heart base
ANY diastolic murmur
ANY continuous murmur
when should you be concerned with heart murmers in cats
Symptomatic – tachypnoeic/ dyspnoeic, syncopal, exercise intolerant, cyanotic etc.
Pyrexic and new murmur
Breeds predisposed to HCM e.g. Sphynx, Ragdoll, Toyger, Persian, Maine Coon, Bengal etc.
ANY diastolic murmur (too fast to tell?)
ANY continuous murmur
Arrhythmia
Gallop sounds
Murmur intensity less useful in cats!
tests for heart murmer
Blood pressure
Blood tests-
CBC, biochem, electrolytes
NT-proBNP- released form heart when it streaches
Cardiac troponin I- use for hf hd and arhythmias, released when cardiomyocyes break down
ECG-
(Holter monitor)
(Loop recorder)
Thoracic imaging-
Radiography
Echocardiography
(CT)
When you’re suspicious of heart disease…..
Gold standard approach:
Bloods (NT-proBNP, cardiac troponin I in certain situations)
Blood pressure
ECG
Echocardiography (in-house vs referral)
Thoracic radiography?
If financial concerns:
ECG if arrhythmia
Echocardiography (likely in-house)
Just NT-proBNP?
Just thoracic radiography?
Pre-analytical error checklist
Is the sample haemolysed/lipaemic/icteric?
Has my sample been taken/handled properly?-
Clotted?
Artefacts can occur if not stored properly
Serum should be separated/spun soon after collection
Too much or too little sample?
Contamination by anti-coagulant
Delay
Pre-analytical error – the right test?
Antigen versus antibody
Most useful test?- FNA in canine mammary tumours vs FNA in canine diffuse large B-cell lymphoma in a lymph node
More than one test:
e.g
Cushing’s:
CBC and biochem
Urine cortisol:creatinine ratio
Basal cortisol
ACTH-stim test
Low-dose dex suppression test
High-dose dex suppression tes
Imaging
Oedema
Changes in the distribution of fluid between the plasma and interstitium are most commonly manifested as oedema, which is defined as accumulation of excess interstitial fluid.
Occurs by:
increased microvascular permeability
increased intravascular hydrostatic pressure
decreased intravascular osmotic pressure
decreased lymphatic drainage
Permeability of endothelium will increase as a physiological response to…
inflammation
Inflammatory mediators will result in the release of cytokines:
interleukin 1 (IL-1)
tumour necrosis factor (TNF)
interferon-γ
Resulting in endothelial cell retraction and widening of interendothelial gaps.
Microvasculature permeability
Increased intravascular hydrostatic pressure as a cause of odema
Increased flow or volume of blood
hyperaemia (active)
congestion (passive)
Decreased Intravascular Osmotic Pressure
as a cause of odema
Osmotic (colloidal) pressure- Maintained by plasma proteins, particularly albumin
Albumin can be decreased due to:
Reduced production- Severe liver disease, Protein starvation
Increased losses-
GI disease-protein losing enteropathy, parasitism
Renal disease- protein losing nephropathy
Decreased lymphatic drainage asa cause of odema
Lymphatic obstruction or compression
Congenital lymphatic aplasia or hypoplasia
Intestinal lymphangiectasia
Lymphangitis- jhones disease
Effusions
Same mechanisms as oedema but into a larger space or cavity
Tap it!
Blood, bile, urine or GIT content?
Transudate, modified transudate or exudate
Cytology
Transudate
extravascular fluid with low protein content (Total protein (g/dL)- <2.5) and a low specific gravity (< 1.012)
It has low nucleated cell counts (Nucleated cells (x103/ul)- <1.5)
Transudates develop most commonly as a result of decreased plasma osmotic pressure.
can be caused by Hypoalbuminaemia.
Modified transudate
an effusion that occurs by transudative mechanisms where vascular fluids leak out of “normal” or “noninflamed” vessels (e.g. via increased capillary hydrostatic pressure or lymphatic obstruction).
Total protein (g/dL)- >2.5
Nucleated cells (x103/ul)- <5
Develops in response to increased hydrostatic pressure or permeability of capillaries and/or lymphatic vessels.
Causes- Cardiac disease, neoplasms, hepatic disease, and feline infectious peritonitis.
Exudate
fluid that leaks out of blood vessels into nearby tissues. The fluid is made of cells, proteins, and solid materials. Exudate may ooze from cuts or from areas of infection or inflammation. It is also called pus
Total protein (g/dL)- >4
Nucleated cells (x103/ul)- >5
Develop because of increased vascular permeability caused by inflammation.
Non-septic exudates are caused by irritants such as bile, urine, and pancreatic enzymes or because of tissue necrosis. Neutrophils in such effusions are nondegenerate.
Septic exudates are caused by microorganisms which may or may not be evident cytologically.
Rivalta test
a test for FIP using effusion
To perform this test, a transparent test tube (volume 10 mL) is filled with approximately 7–8 mL of distilled water to which any one of the following is added:
one drop (20–30 μL) of acetic acid (98–100%)
OR 2-3 drops 25% white vinegar
OR 10 drops of 5% white vinegar
and mixed thoroughly.
On the surface of this solution, 1 drop of the effusion fluid is carefully layered. If the drop disappears and the solution remains clear, the Rivalta’s test is defined as negative. If the drop retains its shape, stays attached to the surface or slowly floats down to the bottom of the tube (drop- or jelly-fish-like), the Rivalta’s test is defined as positive.
Vasculopathy
vascular abnormalities caused by degenerative, metabolic and inflammatory conditions, embolic diseases, coagulative disorders, and functional disorders
Vasculitis
inflammation of the blood vessels/vasculature
Arteritis
inflammation of arteries
Phlebitis
inflammation of veins
Lymphangitis
inflammation of lymphatics
Arteriosclerosis
narrowing of vessels
Atherosclerosis
narrowing of vessels due to deposition of fatty material in vessel walls
Different types of shock
Hypovolaemic
Cardiogenic
Distributive
Hypoxic
(Obstructive)- rare, and falling out of fashion
what does shock mean
HYPOPERFUSION
AND/OR
CELLULAR ANAEROBIC CONDITIONS resulting in HYPERLACTERAEMIA
Hypoxic shock
results from Impaired oxygen delivery to the cells
e.g
Anaemia
Decreased haemoglobin saturation – carbon monoxide. carbon monoxide has greater affinity for haemoglobin than oxogen so takes up the haemoglobin instead of the oxygen
Respiratory disease
Hypovolaemic shock
most common form of shock
fluid lost form intravascular space
comon caues-
acute blood loss
sever dehydration
third spacing- fluid comes form intravascular space into the intrasticial space due to loss of protien and oncotic pressure- e.g protien loosing enteropathy, parvo
Cardiogenic Shock
heart doesnt function properly- weak contractions
could be caused by damage to the myocardium- dilated cardiomyopathy
pulses may not match the heart rate
Distributive Shock
inflamitory markers cuase vessels to become less receptive to constrictive elements and then reamian dilated in situations in which they’d normally constrict
Systemic inflammatory responses (SIRs)-
Heat stroke
Sepsis
may cause cold extremities- freezing mucus membranes
shock symproms
cold extremities
cold mucus membranes
Increased lactate
Metabolic acidosis
Mucous membrane colour change- pale exept for distributive shock
Weak pulses
Increased heart rate (Dogs) or decreased heart rate (cats)
obstructive shock
could be caused by GDV
ondition that prevents blood and oxygen from getting to your organs
types of shcok a GDV can cause
Hypovolaemic shock- third spacing
Cardiogenic shock
Obstructive shock
Distributive
How can we use lactate as a prognostic indicator?
lactate faling with treatment = good prognosis
Haematopoiesis
the formation of:
Erythrocytes
Leukocytes
Platelets
Typically occurs in the bone marrow but extramedullary haematopoiesis also occurs in the spleen and liver
The thymus is responsible for T-lymphocyte maturation- Compare the Bursa in birds
Lymph nodes:
Not present in birds
Filter lymph for antigen presentation and response
Clinical signs associated with disorders of the haemolymphoid system:
Enlarged lymph nodes
Anaemia
Coagulopathies
Oedema
lymphomegaly
Enlarged lymph nodes
Causes of lymphomegaly:
Reactive- Reactive lymphoid hyperplasia. reacting to infection in other areas. the lymphnode affected depends on the sites that drain into it
Inflammation/infection- Lymphadenitis
Neoplastic
Diagnostic tools:
FNA- Avoid those lymphnodes draining the mouth
Biopsy
Questions for the pathologist:
One cell predominates or mixed?
Which cells are there more of?
Regular or irregular?
Maintenance of tissue architecture?
Necrosis?
Lymphoid atrophy
Congenital immunodeficiencies
Viral infections
Cachexia/malnutrition
Aging
Radiation and chemotherapy
Toxins
Bone marrow histology
Hematopoietic tissue is highly proliferative.
Pluripotent hematopoietic stem cells (HSCs) are a self-renewing population, giving rise to cells with committed differentiation programs, and are common ancestors of all blood cells.
Control of haematopoiesis is complex
The dominant regulator of erythropoiesis is erythropoietin (Epo) produced by the kidney
Iron is essential to haemoglobin formation and function
Typically the bone marrow only releases mature cells, however in times of increased need, immature cells will be released into the blood stream
Hence looking for polychromasia/reticulocytes in cases of anaemia to assess for regeneration
And band neutrophils/left shift in inflammation/infection
Infectious agents of circulating cells
Others are essentially non-pathogenic under most circumstances
Do not confuse with artefacts/mimics – Heinz bodies, etc
Anaplasma-
A. phagocytophilum – Tick-Borne Fever in ruminants
Leukocytes, erythrocytes, platelets
Babesia-
In cattle in UK – Babesia bovis
Erythrocytes
Theileria-
Not in UK – East Coast Fever in cattle
Reproduction by schizogony in lymphocytes (tissue/leukocytic phase) then fission in erythrocytes
Ehrlichia-
Not in UK?
Leukocytes
Mycoplasma-
Cats
Formerly Haemobartonella
Erythrocytes
The hemolytic anemia caused by M. haemofelis is called Feline Infectious Anemia (FIA)
Cytauxzoon-
Not UK
Cats
Ertyrhocytes plus macrophages in tissues
Birds-
Hemoproteus, Leukocytozoon, Plasmodium
Infectious agents within macrophages in tissues
Leishmania-
Protozoa
Spread by sandfly
Amastigote stage found in macrophages
Granulomatous dermatitis in cutaneous form
Granulomatous splenitis, lymphadenitis and hepatitis in visceral form
Histoplasmosis-
Fungus
Soil-borne
Typically seen in the lungs (ddx: Blastomycosis)
Will spread to lymph nodes
Acute lymphadenitis
Typically due to pyogenic bacteria- Acute suppurative lymphadenitis
Streptococcus equissp.equi (Strangles)
Rhodococcus equi
Trueperella pyogenes
Chronic lymphadenitis
Typically due to intracellular and/or persistent bacteria
Chronic (pyo)granulomatous lymphadenitis
Mycobacterium bovis
Mycobacterium aviumsubspeciesparatuberculosis- Johne’s
Corynebacterium pseudotuberculosis
Also parasites and fungi – see previous slide
Canine sterile granulomatous lymphadenitis
Puppy strangles
Infection and inflammation of the spleen
Primary isolated splenitis is generally uncommon in dogs and cats-
Often secondary to another disease process, such as peritonitis or neoplasia
Or in cattle may see granulomas caused by Mycobacterium bovis in addition to other organs
Leishmania and Hepatozoon (not in UK) should be consider as primary causes of splenitis in dogs however often other organs affected
In cats consider Tularaemia - Francisella tularensis
Zoonotic and potential to be weaponised
Not in UK
Lymphadenitis also
Severe lymphoid depletion in the spleen and thymus is a feature of numerous viral diseases, including rinderpest, canine distemper, equine herpes virus, canine parvoviral enteritis, feline panleukopenia, and bovine viral diarrhoea
Necrotizing lymphadenitis, splenitis, and hepatitis in laboratory animals due to various infectious agents:
Tyzzer’s disease (Clostridium piliformis):
Mice, gerbils, and other laboratory and wild rodents
Multifocal foci of hepatic necrosis (older mice), catarrhal enterocolitis with mesenteric lymph node abscesses (younger mice); myocardial lesions occasionally (especially gerbils)
Yersiniosis (Yersinia pseudotuberculosis):
Cats, Guinea pigs, rabbits, rats, other rodents
Acute: Enteritis (ileum) with mucosal ulceration
Subacute to chronic: Discrete miliary to caseous lesions in lymph nodes, spleen, liver and lungs
Bacteria are easy to visualize, in contrast to F. tularensis
Salmonellosis (Salmonella sp.):
Guinea pigs, mice, rats, other rodents
Acutely–focal areas of necrosis in liver, spleen, and lymphoid tissue and intestine
Bubonic plague (Yersinia pestis):
Rats, squirrels, and other rodents
Viral causes of immunodeficiency
Parvoviruses-
Replication depends on host-cell DNA polymerases produced in the S phase of the cell cycle. Therefore, has a predilection for cells that are rapidly dividing- Foetal tissues – heart (puppies), cerebellum (kittens), haematopoietic and lymphoid tissues, intestinal crypt epithelium
Bovine Viral Diarrhoea Virus (BVDV)-
Subclinical infection usually by non-cytopathic BVD followed by seroconversion is the most common form- Transient leukopenia may be seen with onset of signs of disease.
Infection of the dam- 50-100 days gestation: Foetal death, abortion, mummification
100-150 days gestation: Congenital brain defects, cataracts microphthalmia
Persistent infection is an important sequela of foetal infection with noncytopathic BVDV occurring with infection prior to 125 days gestation- Persistently infected calves may appear healthy and normal in size, or may be stunted and prone to respiratory or enteric infections. Viraemic but do not seroconvert
Superinfection of the PI calf with cytopathic form = mucosal disease- Fever, leukopenia, dysenteric diarrhoea, inappetence, dehydration, ulcers of the nares and mouth. Death within a few days of onset.
PM -> Erosions and ulcerations throughout the GI tract., mucosa over Peyer’s patches haemorrhagic and necrotic, extensive necrosis of lymphoid tissues
Feline immunodeficiency virus (FIV)
Three phases of infection - the acute phase, the asymptomatic (or latent) phase, and the progressive phase.
Acute phase-
generally occurs 1-3 months after infection
Replicates in T-cells of within lymph nodes
Spreads to other lymph nodes, resulting intransient lymphomegaly and fever
Asymptomatic phase-
Months to years.
Replicates very slowly
Cyclical lymphopaenia and/or increased globulins
Some cats will remain in this stage and never progress to more severe disease.
NEVER euthanise a cat on a snap test alone
FIV (Feline Immunodeficiency Virus) (cats.org.uk)
Progressive phase-
Progressive immuno-compromised state
Secondary infections may occur – gingivitis very common
Ongogenic (see next slide)
Snap test tests for the antibody
Feline leukaemia virus (FeLV)-
Subgroups A,B,C & T; A, B, and C are most important
FeLV-A is the only one that is contagious, found in almost 100% infected cats and is predominately immunosuppressive; FeLV-B and C results from recombination or mutation
FeLV-B is found in ~50% of infected cats; commonly associated with neoplastic transformation and lymphoma (see next slide)
FeLV-C arises from a mutation of the envelope gene of FeLV-A; it is present in about 1% of infections and is associated with anaemia following bone marrow infection (non-regenerative)
Snap test tests for the antigen
Oncogenic viruses of the lymphoid system
Retroviruses
Insert copies of their RNA into host DNA
Bovine leukaemia virus - Notifiable
Avian leukosis
Lentiviruses-
FIV
FeLV
Maedi-Visna
FIV- The risk for developing lymphoma in FIV-infected cats is fivefold to sixfold higher than in uninfected cats
Intestinal B-cell lymphoma
FeLV- Lymphoma is increased 60-fold in infected cats
Commonly results in T-cell mediastinal/thymic lymphoma
Vaccination has markedly reduced this
diffusely enlarged spleen causes
Congested/bloody-
Torsion
Barbiturate euthanasia
Acute haemolytic crisis
African swine fever
Septicaemia- Salmonella, Anthrax
Non-congested/firm/meaty
Neoplasia- Lymphoma, Mast cell tumour (cats)
Chronic immune-mediated haemolytic anaemia
Chronic infection- Mycoplasma, etc
Chronic inflammation
Anthrax
Anthrax is a cause of outbreaks of sudden death, particularly in ruminants, however can affect other grazing animals and humans.
Clinical signs in animals that do not die suddenly include high fever, tachycardia and tachypnoea, and congested and terminally cyanotic mucosae with haemorrhage. Animals that survive longer than a day may have dysentery, abortion, oedematous swellings of the perineum, throat and abdominal wall, and blood-stained milk.
The characteristic sign in pigs is swelling of the pharyngeal region and neck.
Anthrax is notifiable and zoonotic, so if you suspect it you must call APHA
Due to the high fever, animals decompose rapidly resulting in typical saw-horse bloated appearance
DO NOT open up the animal, it is spread by spores which can become aerosolised
If the animal has been accidentally opened up, immediate gross post mortem findings include blood filled cavities and marked splenomegaly
Diagnosed in field by taking a blood smear from the ear
Rod-shaped bacteria with capsule
African Swine Fever
Forms and clinical signs-
Peracute, acute, subacute, and chronic forms
High fever
Cutaneous erythema in all forms
Dyspnoea, vomiting
Chronic form – abortion, lameness, pneumonia, wasting
Pathology-
Enlarged friable spleen
Haemorrhages in lymph nodes, particularly gastrohepatic
Petechial haemorrhage in kidneys and peri-renal oedema
Tri-cavity effusions
Marked pulmonary oedema
Gall bladder oedema
Classical swine fever
Forms and clinical signs-
Peracute, acute, subacute, and chronic forms
High fever
Generalised vasculitis results in haemorrhages, infarction and cyanosis
Infarction of ear tips will result in necrosis
Chronic form – marked weight loss, poor reproductive performance, abortion or weak tremoring piglets
Pathology-
Splenic infarctions
Haemorrhages in lymph nodes and necrosis of tonsils
Chronic - mucosal ulcers at ileocaecal junction, lymphoid atrophy in lymph nodes and thymus
Splenic masses
Discrete single or multiple splenic masses are common in the aged dog
Bloody versus firm
Irrespective of the diagnosis, they will commonly rupture resulting in a haemoabdomen
Rarer in cats, where mast cell tumours are the most common splenic tumour and tend to cause diffuse enlargement
Benign- Nodular hyperplasia
Haemangioma
Haematoma
Indolent- Marginal zone lymphoma
Malignant- Haemangiosarcoma
Histiocytic sarcoma
petechia
is a pinpoint (1 to 2 mm) haemorrhage that occurs mainly because of diapedesis associated with minor vascular damage
ecchymosis
larger than petechia
up to 2 to 3 cm in diameter haemorrhage that occurs with more extensive vascular damage
Suffusive haemorrhage
affects larger contiguous areas of tissue than petechia and ecchymosis
haematoma
Haemorrhage that occurs in a focal, confined space forms a haematoma, most common in the ears of long-eared dogs or pigs and in the spleen after trauma to the vasculature
Haemoperitoneum
blood in the peritoneal cavity
Haemothorax
blood in the thoracic cavity
Haemopericardium
blood in the pericardial sac
Aneurysm
bulge in an artery due to defect in the wall
Arterial aneurysms
Arterial aneurysms and their subsequent ruptures are rare in animals
Rupture of the aorta, pulmonary artery and coronary artery has been reported in swine and turkeys fed a diet deficient in copper
Dissecting aneurysms in the coronary and renal arteries in young male racing greyhounds, probably due to arteriosclerosis and haemodynamic stress
In horses, aortic sinus of Valsalva aneurysms or tears in the aortic root are well‐recognised conditions in breeding stallions, often leading to sudden death.
Developmental collagen disorders, such as the Ehlers-Danlos and Marfan syndrome
Smaller haemorrhages in vitamin C deficiency (scurvy) in guinea pigs and primates
Minor endothelial injury
->small numbers of erythrocytes escape by diapedesis
caused by:
Endotoxemia- toxins produced by baceria in the gut
Infectious agents- canine adenovirus-1, adeno viruses are endothelialtrophic
Chemicals- uremic toxins
Immune complexes can become entrapped between endothelial cells and activate complement and neutrophil influx to result in damage to the endothelium and vessel wall-
Feline infectious peritonitis- why cats get swollen belly. damaged endothelium causes leakage
Recap - see glomerulonephritis section in kidney biopsy lecture
the 4 phases of Haemostasis
haemostasis- stopping bleeding
Arteriolar vasoconstriction-
Transient
Mediated by reflex neurogenic mechanisms
Primary haemostasis-
Formation of platelet plug
Secondary haemostasis-
Clotting factors and production of fibrin
Thrombus and antithrombotic events (resolution)
Primary haemostasis
Adhesion-
vWF (von willebrand factor) is released by local activated endothelium and coats the exposed collagen
vWF acts as a bridge between platelet surface receptor and collagen
Activation-
Caused by thrombin and ADP
Results in shape change and release of thromboxane- go from round to flattened to bridge gap
further release of prothrombotic agents
Aggregation-
Glycoprotein IIb/IIIa allows binding of fibrinogen
Fibrin (formed by 2ry haemostasis) stabilises
chediak-higashi syndrome
assosiated with chnge in coat colour
aleutian mink, cattle, persian cata
Congenital disorders of 1ry haemostasis
defective storage of ADP
what can negativly effect platlet function
NSAIDs
Aspirin inhibits cox
Resulting in less thromboxane and thus no platelet aggregation
Uraemia
Idiopathic immune-mediated thrombocytopaenia- imunne system destroys platlets
Buccal Mucosal Bleeding Time
The buccal mucosal bleeding time (BMBT) is a test of platelet function. It is indicated in patients suspected of having a primary hemostatic defect despite adequate platelet numbers. Its use and accuracy for the assessment of platelet function are controversial, but it is still widely used in clinical practice for lack of a more accurate or specific test.
Method:For a BMBT, the patient is restrained in lateral recumbency and may require light sedation. A strip of gauze is tied around the maxilla to fold up the upper lip sufficiently to cause moderate mucosal engorgement. It is important not to place the gauze too tightly so that blood vessels are not constricted. The BMBT should be performed with a commercial spring-loaded device that creates a small incision of uniform width and depth into the inside of the upper lip. An area devoid of visible blood vessels should be chosen. Any shed blood must be carefully blotted with filter paper, with extreme care taken not to blot the incision itself; doing so may disturb the fragile primary platelet plug (Figure 3). The time taken from incision to cessation of bleeding by first clot formation is recorded (normal = 2–4 minutes in dogs, 1–2.5 minutes in cats).
Secondary haemostasis
Coagulation factors are-
Plasma proteins, Produced mainly by the liver.
Subdivided into :
Intrinsic pathway-
factors XI and XII
Extrinsic pathway-
VII
both lead into common pathway
Common pathway
Starts with X
Results in formation of thrombin which cleaves fibrinogen to fibrin
Vitamin K– dependent factors
Span all three parts
II, VII, IX, and X
Congenital disorders of 2ry haemostasis
Factor IX deficiency- Haemophilia B: dogs, cats and rarely horses. generally mild in cats and small dogs. more severe in large dogs
Factor VIII deficiency- Hemophilia A:
dogs, horses, cattle sheep , cats. vleeding can be severe in large dogs and horses
Liver disease
VitK deficiency-
factors II, VII, IX, X
warfarin containing/ like rodenticides
Testing 2ry haemostasis
Prothrombin Time-
Purpose. The prothrombin time (PT), also known as one-stage PT, is the principal test of the extrinsic pathway, but it also tests the common pathway. Because of the short half-life of factor VII, PT is a very sensitive test for early vitamin K deficiency or antagonism (eg, anticoagulant rodenticides). This test result is not affected by the presence of primary hemostatic disorders.
Activated Partial Thromboplastin Time-
Purpose. The activated partial thromboplastin time (aPTT) tests the intrinsic and common pathways. It is typically prolonged in patients with heritable factor deficiencies (eg, hemophilia A) or hepatic synthetic dysfunction, or in patients with disseminated intravascular coagulation that have consumed clotting factors.
Prothrombin Time
Purpose. The prothrombin time (PT), also known as one-stage PT, is the principal test of the extrinsic pathway, but it also tests the common pathway. Because of the short half-life of factor VII, PT is a very sensitive test for early vitamin K deficiency or antagonism (eg, anticoagulant rodenticides). This test result is not affected by the presence of primary hemostatic disorders.
Activated Partial Thromboplastin Time
Purpose. The activated partial thromboplastin time (aPTT) tests the intrinsic and common pathways. It is typically prolonged in patients with heritable factor deficiencies (eg, hemophilia A) or hepatic synthetic dysfunction, or in patients with disseminated intravascular coagulation that have consumed clotting factors.
thrombus
A thrombus forms antemortem within a vessel
thromboembolism
a section of a thrombus that has broken off and lodged elsewhere
antemortem clot
An antemortem clot is a coagulum of blood and/or plasma that forms when bleeding into a cavity
Post mortem clots
are found within vessels and the heart and are a product of blood stasis and clotting post mortem
virchows triad
need one of these three things to form a thrombus
Abnormal blood flow-
Valvular disease
Heart disease
Shunts
Aneurysms
Hypovolaemia
Torsions
Hypercoagulability-
Glomerular disease- Loss of antithrombin 3
Metabolic disease
Inflammation
Platelet activation- Neoplasia
Endothelial injury-
Infectious diseases
Free-radicals - vit e/selenium deficiency
Toxins
Trauma
severe cases will have all three
Thrombosis factor – abnormal flow
Local stasis or reduced flow (e.g., gastric dilation and volvulus, intestinal torsion and volvulus, varicocoele, external compression of vessel)
Cardiac disease (e.g., cardiomyopathy, cardiac hypertrophy)
Aneurysm (e.g., copper deficiency in pigs, Strongylus vulgaris)
Hypovolemia (e.g., shock, diarrhoea, and burns)
Normal blood flow is laminar such that the platelets (and other blood cellular elements) flow centrally in the vessel lumen, separated from endothelium by a slower moving layer of plasma.
Thrombosis factors– hypercoagulability
Anti-thrombin 3-
an important anti-coagulant
it is a small molecule thus one of the first to be lost with glomerulonephritis
Aortic trifurcation thrombosis is an important but relatively uncommon sequel of hyperadrenocorticism in dogs-
Pathogenesis not completely understood:
Thrombocytosis
Decreased antithrombin concentrations secondary to glomerular changes and proteinuria
Decreased fibrinolysis
Relative increases in the concentrations of circulating procoagulant molecules, such as factor VIII and fibrinogen
In humans, 80% of patients with diabetes mellitus die a thrombotic death- The plasma levels of many clotting factors including fibrinogen, factor VII, factor VIII, factor XI, factor XII, kallikrein, and von Willebrand factor are elevated in diabetes
DM a potential sequel of HAC
Thrombosis factors – the endothelial cell
Roles of the endothelial cell-
Solute/metabolite diffusion/transport
Local vasoconstriction and vasodilation
Coagulation
Inflammation
Wound healing and angiogenesis
In normal circumstances the endothelial cells are slightly anti-coagulant, but become pro-coagulant when needed
vonWillebrand’s factor plays a crucial role in primary coagulation-
Synthesized in endothelial cells (and megakaryocytes)
Stored in Weibel-Palade bodies
vWF enables adhesion of platelets to subendothelial extracellular matrix
Thrombosis factors – Disseminated Intravascular Coagulation
Diffuse or severe endothelial damage and/or platelet activation with or without severe inflammation can result in disseminated intravascular coagulation (DIC)
DIC results in widespread consumption of clotting factors and platelets = consumptive coagulopathy
The outcome is microthrombi within small vessels which can contribute to multi organ failure (MOD) and widespread haemorrhage
Thrombosis – morphology
Thrombi can develop anywhere within the CVS
Arterial thrombi
Venous thrombi-
Slower flowing blood so will typically completely occlude vessel and take the form of the vessel
Post mortem clotting-
Not adherent to the wall of the vessel
Separates into cells and plasma = chicken fat clot
Thrombosis – infarction
An infarct is a local area of very acute (peracute) ischemia (complete lack of oxygen) that undergoes coagulative necrosis.
Infarction is caused by the same events that result in ischemia and is most common secondary to thrombosis or thromboembolism.
The characteristics of an infarct are variable based on the type and size of vessel that was occluded (artery or vein), the duration of the occlusion, the tissue in which it occurs, and the prior perfusion and vitality of the tissue.
Disorders of Primary Haemostasis Clinical presentation
Epistaxis- nose bleed
Spontaneous haemorrhage
Gastrointestinal bleeding
Prolonged bleeding after surgery
Excessive menstruation in intact females
Ecchymosis, petechiae, bruising
Primary Haemostasis Investigation
Buccal mucosal bleeding time (BMBT)
Mucosal membrane of the lip
Standardised cut made in lip, e.g.: 5 x 1 mm
End point = bleeding stops & crescent of blood no longer forms on filter paper
Normal <4min (dogs) <3mins (cats)
Prolonged BMBT causes
Thrombocytopenia-
Consumption, haemorrhage
Immune mediated thrombocytopaenia
Disseminated intravascular haemolysis (DIC)
Decreased platelet function-
Rare inherited disorders
Platelet function inhibited by uraemia of renal failure
Therapy, e.g.: Aspirin
Von Willebrand’s Disease-
Lack of or reduced amounts of Von Willebrand’s Factor
Dobermans
Platelet concentration determined by
haematology analyser
Units: # x10^9/L
Counted in the same channel as erythrocytes
However platelets are smaller
pseudo thrombocytopenia
Platelet clumps-
Clotting during sampling
In vivo activation
Platelets counted as RBCs (and vice versa)-
Dogs:
Akitas: Small red blood cells
CKCS: Macroplatelets
Cats, Goats:
Small red blood cells
Platelets - Manual Assessment
Thrombocytopenia?
→ ALWAYS CHECK A BLOOD SMEAR!
Check for platelet clumps (feathered edge)
Manual count
Body of the smear
count how many platets you can see in each hightly magnified field of view
Average of 10 hpf x 15
count how many platets you can see in each hightly magnified field of view
over 150-200 is good
Check for Macroplatelets
May also effect [RBC]
lower count of macroplatlets ok
Immune Mediated Thrombocytopenia (IMTP
Thrombocytopenia (<10 x10^9/L, normal: >150)-
Antibodies bind directly or indirectly to platelets
Platelets are destroyed / phagocytosed by macrophages
Primary-
Idiopathic
Most common in dogs
IMHA + IMTP = Evan’s Syndrome
Secondary-
Drugs (e.g.: Sulphonamides in dogs, Methimazole in cats)
Infections (e.g.: Ehrlichia, Leishmania)
Neoplasia
Diagnosis-
Spontaneous haemorrhage
Thrombocytopenia <10 x10^9/L
Confirmed on blood film examination
Diagnosis of exclusion
Therapy-
Immunosuppression: Steroids, Azothioprine with supportive care
Disseminated intravascular coagulation
DIC-
Widespread uncontrolled activation of coagulation cascade
Platelets are consumed → thrombocytopenia
Clots are dissolved → Excessive fibrinolysis = ↑ D-Dimers
must have all 3
FDPs- no comercially availabe
Causes-
Envenomation
Systemic inflammation / infection (e.g.: Septicaemia, vasculitis)
Massive necrosis
Heat stroke
D-Dimers
Measured on citrated plasma
Form when cross linked fibrin is cleaved by plasmin
Used to assess ↑ fibrinolysis associated with coagulation
Clots are dissolved → excessive fibrinolysis = ↑ D-Dimers
Causes for high level
Localised or disseminated intravascular coagulation (DIC)
Sepsis, systemic inflammation, haemorrhage, neoplasia, surgery, immune-mediated disease
Decreased hepatic or renal clearance
Angiostrongylus vasorum
Angiostrongylus vasorum = Lungworm
Becoming more common in the UK
Infected by ingestion of slugs and snail (intermediate host)
Clinical presentation
Coughing / Difficulty breathing
Inappetent
Vomiting or diarrhoea
Weight loss
Depression / Lethargy
Bleeding: Cutaneous bruising and intra-cavitatory haemorrhage
Bleeding pathogenesis: Excessive intravascular coagulation
Thrombocytopenia (consumption)
Consumption of coagulation factors
Diagnosis
Broncho-alveolar Lavage (BAL) & Cytology
Faecal analysis: Baermann technique
PCR: Faeces, blood, BAL
ELISA test: Detects antigen
Therapy
Moxidectin & Imidacloprid, Milbemycin oxime & Praziquantel
Von Willebrand Disease
Von Willebrand factor (vWF)
Exposed when vessel wall is damaged
Binds platelets to endothelial wall
Von Willebrand Disease
Most common hereditary bleeding disease in dogs
Doberman most common breed
Different types = Reduced concentration or complete absence of vWF
Presentation-
Mucosal haemorrhage: Epistaxis, GI haemorrhage, prolonged oestrus
Prolonged bleeding after surgery
Cutaneous bruising
Diagnosis-
Prolonged buccal mucosal bleeding time
Measurement of vWF: <50% = Decreased
Genetic test for vWD type I (most common)
APTT and PT
Coagulation times’ = APTT and PT-
Stimulate the coagulation pathway in vivo
The it takes until a clot is detected
Activated partial thromboplastin time = APTT
Assesses intrinsic + common pathways
Prothrombin time = PT
Assesses extrinsic + common pathways
Differentials for prolonged APTT
Intrinsic + Common factors
XII, XI, IX, VIII, X, V, II, I
Hereditary-
Haemophilia A = deficiency in factor VIII
Haemophilia B = deficiency in factor IX
Factor XII deficiency = most common in cats, no clinical haemorrhage
Acquired-
Hepatic disease
Vitamin K malabsorption
Vitamin K antagonism (rodenticide toxicity)
DIC or local consumption of coagulation factors
Differentials for prolonged PT
Extrinsic + Common factors
VII, X, V, II, I
Hereditary
Factor VII - prolonged PT, normal aPTT
Affected dogs generally do not have a history of bleeding
Bruising / prolonged bleeding following surgery
Acquired
Hepatic disease
Vitamin K malabsorption / antagonism (rodenticide toxicity), this goes up first in this case
DIC or local consumption of coagulation factors
Vitamin K Deficiency / Antagonism
Vitamin K dependent factors-
Factors II, VII, IX & X
These factors require Vitamin K to be functional
Malabsorption of Vitamin K-
Gastrointestinal disease (e.g. inflammatory bowel disease)
Vitamin K antagonism-
Rodenticide toxicity (e.g. Warfarin) - dogs
Mouldy sweet clover - ruminants, horses, pigs
Rodenticide Toxicity
Very common in dogs
Clotting factors II, VII, IX and X affected
Diagnosis
Visible clinical signs can take 5-7 days to appear after ingestion
Monitor clotting times on a daily basis for at least 3 days
Prothrombin time (PT) will become prolonged first
Therapy
Vitamin K1 supplementation
Severe cases → plasma / blood transfusions
Replaces coagulation factors to allow rapid cessation of haemorrhage
Haemophilia A = Factor VIII
Diagnosis
<1% factor VIII activity: reference interval: 50-200%
Prolonged APTT only (not PT)
All animals
Severe in larger dogs, horses & japanese brown cattle
X-linked recessive mutation in Factor VIII gene
Males are either affected or not (never carriers)
Females can be free of the defect, carriers (heterozygous) or rarely affected (homozygous).
Haemophilia B = Factor IX
Diagnosis
<1% factor VIII activity: reference interval: 50-200%
Prolonged APTT only (not PT)
Dogs & cats
Mild in small dogs, severe in large dogs
X-linked recessive mutation in Factor VIII gene
Males are either affected or not (never carriers)
Females can be free of the defect, carriers (heterozygous) or rarely affected (homozygous).
What is jaundice?
Excessive accumulation of the yellow/orange pigment (bilirubin) in the tissues and blood (hyperbilirubinaemia)
Bilirubin ismade during the normal process of breaking down red blood cells.
Most often seen in the shclera , mm skin
Unconjudated bilirubin
direct breakdown product of haem – in soluble and can only travel in blood stream attached to albumin and unable to excrete directly from the body
Uncojudated bilirubin is formed by the breakdown of hemoglobin in the red blood cells. The liver converts this bilirubin into direct bilirubin, which can then be released into the intestine by the gallbladder for elimination. Total bilirubin levels are therefore indicative of both the destruction of red blood cells and the proper functioning of the liver, gallbladder, and bile ducts.
This is bound to albumin and is the dominant form of total bilirubin in blood. It is produced in macrophages from breakdown of heme groups (specifically the porphyrin ring of heme). The biggest source of heme is hemoglobin within red blood cells (RBC)
Unconjugated bilirubin is then released into plasma where it binds to albumin. Uptake of unconjugated bilirubin occurs in the liver and is carrier-mediated and passive.
Once within the hepatocyte mitochondria, unconjugated bilirubin is transported with ligandin (Y protein or glutathione-S-transferase A) or other proteins (e.g. fatty acid binding protein) and the majority is conjugated to glucuronic acid by UDP-glucuronyl transferase (from the UGT1A1 gene).
Under physiologic conditions, most of the unconjugated bilirubin in blood comes from normal RBC turnover, where RBCs that have completed their normal lifespan (effete) are removed by macrophages in the spleen, liver and bone marrow. Small amounts of bilirubin also come from other heme-containing proteins, such as myoglobin. As RBCs age, they accumulate oxidative injury, which causes exposure of an antigen on RBCs, which is recognized by macrophage receptors, resulting in phagocytosis (extravascular hemolysis) and conversion of the porphyrin ring of hemoglobin into biliverdin and then unconjugated bilirubin (indirect bilirubin on chemistry panels).Macrophages export the unconjugated bilirubin into blood, where it binds to albumin as it is water insoluble. The albumin-bound unconjugated bilirubin is take up by transporters in the hepatocytes on the sinusoidal (blood or lumen) side of the membrane. The unconjugated bilirubin is transported internally within the hepatocyte by ligandin or Z protein and then conjugated to glucuronic acid (glucose in horses) to form conjugated bilirubin (direct bilirubin on chemistry panels), which is water soluble.
conjudated bilirubin
water soluble and can be excreted from the body
Conjugation renders bilirubin water soluble. Only very small amounts in blood because it is normally excreted into bile.
The conjugated bilirubin is then excreted into the biliary system by transporters on the canalicular or biliary side of the membrane (different from those that take up unconjugated bilirubin from blood) along with bile salts and is either stored in the gall bladder (for those species with a gall bladder) or excreted directly into the small intestine. Within the small intestine, the conjugated bilirubin is degraded by bacterial proteases to urobilinogen, around 10% of which undergoes enterohepatic recirculation after uptake by the portal vein. The “reclaimed” urobilinogen is then freely filtered by the glomerulus and is found in urine (there is a pad for urobilinogen on a urinary dipstick but it is not used in veterinary medicine as a diagnostic test). The rest of the urobilinogen is reduced to stercobilin (either directly or via stercobilinogen), which is excreted in the feces. Stercobilin imparts the brown color to normal feces.The excretion of conjugated bilirubin into bile is the rate-limiting step of the entire pathway of bilirubin metabolism and is ATP- or energy-dependent.
Pre hepatic icterus
Accelerated red blood cell destruction and increased bilirubin production
Immune mediated haemolytic anaemia (IMHA)
If this bilirubinemia overwhelms the liver’s functional capacity for uptake, conjugation, and secretion, bilirubin is refluxed from the liver into the circulation resulting in hyperbilirubinemia and icterus.2
Hepatic icterus
Hepatocellular disease-
Reduced hepatocyte uptake
Reduced Conjugation
Reduced secretion of bilirubin
intrahepatic cholestasis associated with hepatocellular injury, necrosis, or dysfunction
Hyperbilirubinemia that occurs in most diseases of the liver is a mixture of conjugated and unconjugated bilirubin in varying proportions – reflux back into the intravascular system
Viruses heptatp toxic drugs
Post hepatic icterus
Disruption of bile flow through the extrahepatic biliary system- gall stones, tumours ect
often show the most yellowing of the skin
diagnostics for prehepatic jaundice
icteric plasma
Saline agglutination
Coombs test
Blood smear
diagnostics for Hepatic icterus
can detect whether the problem is the liver by Liver disease is more common cause of incterus in non=haemytic patients
can detect whether the problem is the liver by:
The blood test
ALT
ALP
GGT
AST
however most systemic diseases will affect liver and therefore affact these so instead you can do :
BAST= shows liver function
Bile acid stimulation test for liver function
liver disease include viral or bacterial infections, ingestion of toxic plants or chemicals, certain drugs and medications, cancer, autoimmune diseases, and certain breed-specific liver diseases.
diagnostics for post hepatic icterus
Gall bladder obstruction
Extremely icteric
Obstruction of the common bile duct is associated with a number of diverse primary conditions, including inflammation (eg, pancreatitis, duodenitis, duodenal foreign body, etc), cholelithiasis, gallbladder mucocele, choledochitis/cholecystitis, neoplasia, bile duct malformations, parasitic infection, extrinsic compression, fibrosis, and bile duct stricture.
can see some of these on ultrasound
ALP and GGT increase more
gallbladder mucocele- looks like kiwi fruit on ultrasound, common in older border terriers
steps of acute inflammation
Fluidic- Vasodilation
Increased vascular permeability
Cellular- Leukocyte recruitment
Causes of inflammation
infections- Bacterial, viral, fungal, parasitic
Microbial toxins
Different pathogens elicit varied inflammatory response
Tissue necrosis - Elicits inflammation by releasing molecules from necrotic cells, regardless of the cause of cell death
Ischaemia, trauma, and physical and chemical injury
Foreign bodies - May elicit inflammation themselves or because they cause traumatic tissue injury or carry microbes
Immune reactions = hypersensitivity - Reactions in which the normal protective immune system damages the individual’s own tissues.
Acute inflammation – fluidic phase
Two key features of fluidic phase of acute inflammation-
Vasodilation
Increased vascular permeability
chemical mediators-
preformed mediators on scretory granules- histamine ect
newly synthesised mediators made at time of inflamation- cytikines ect
from the liver- factor xII, complement activation
histamine
Produced by mast cells in the Acute fliudic phase of inflamation
Mast cells are normally distributed throughout connective tissue adjacent to blood vessels and lymphatics within the skin and mucosa
When exposed to inciting agent and IgE, degranulate to release histamine
Histamine is a vasoactive amine-> vasodilation and increased permeability
arachidonic acid
produced in acute fluidic phase of inflamation
Arachidonic acid metabolites include :
Prostaglandins
Thromboxane
AA metabolites, generally in the acute phase, results in vasodilation and platelet aggregation
Made from cell membrane phospholipids
Formation is inhibited by some well-know anti-inflammatories-
Steroids
Meloxicam (Cox-inhibitors)
Aspirin
cytokines TNF and IL-1
produced in fluidic phase of acute inflamation
TNF and IL-1 secretion stimulated by:
microbial products
immune complexes
Foreign bodies
physical injury
others
Mainly produced by macrophages and dendritic cells
TNF also made by T cells and mast cells
IL-1 made by some epithelium
dendritic cells
part of the fluidic phase of acute inflamation
Dendritic cells are antigen presenting cells
Initially inciting the innate (non-specific) immune system- Produce pro-inflammatory cytokines
Mature to also activate the adaptive (specific) immune response
systematic effects of acute inflamation
TNF and IL 1 are joined by IL-6
IL-6 goes to brain and produces fever
fibrinogen tells bone marrow to make wbc
tumour necrosis factor slows heart
thrombus formation
infalamtion and coagulation are intrinscally linked- facotr 12 is key chemical mediator
Acute inflammation and coagulation
Coagulation and inflammation are activated by similar insults
Key parts of the coagulation cascade, like thrombin and fibrinogen, are also seen with inflammation
Thrombin-
Cleaves fibrinogen to fibrin -> clot
And is proinflammatory as is a monocyte chemoattractant, induces TNF, IL-1 and IL-6 production and mediates leukocyte migration
Fibrinogen -
Is a glycoprotein synthesized by hepatocytes
In pathological conditions, blood concentration of fibrinogen increases= acute phase protein
Crucial for scaffolding the haemostatic plug
Proinflammatory due to its function of binding and activating leukocytes
morphological presentations of exudation (acute inflamation)
Catarrhal/mucoid
Serous
Fibrinous
Suppurative/purulent
Serous exudation
Exudation of cell-poor fluid into spaces created by cell injury or into body cavities (effusions)
Fluid is not infected & does not contain high numbers of leukocytes.
Seen with:
Thermal injury to skin - blisters
Acute allergic responses - watery eyes/runny nose
may not be classified as true exudation
Catarrhal/mucoid exudation
Secretion of thick gelatinous fluid
Contains mucus and mucins
Occurs most commonly in tissue with abundant goblet cells & mucous glands – runny nose
Fibrinous exudation
Characteristic of inflammation of membranes of body cavities and organs-
meninges, pericardium, joints
Most commonly caused by infectious microbes
Suppurative/purulent exudation
Pus = an exudate consisting of neutrophils, the liquefied debris of necrotic cells, and oedema fluid.
The most frequent cause = infection with bacteria that cause liquefactive tissue necrosis
e.g. Staphylococci - aka pyogenic (pus-producing) bacteria.
Acute inflammation – neutrophils
Neutrophils are typically the first to arrive- not resident in cells but attracted to inflamation
In most forms of acute inflammation neutrophils predominate during the first 6-24hrs-
More numerous in the blood than other leukocytes
Respond more rapidly to chemokines
After entering tissues, neutrophils are short-lived; undergo apoptosis and disappear within 24-48hrs
Functions-
perform phagocytosis
recruit other effector cells
Release anti-microbial agents
Chronic inflammation
Inflammation that occurs over a prolonged time and/or fails to resolve.
Occurs due to:
The acute inflammatory response fails to eliminate the inciting stimulus.
After repeated episodes of acute inflammation.
In response to specific pathogens.
Biological mechanisms that result in chronic inflammation
Resistance to phagocytosis:
Fusobacterium necrophorum- Produces leukocidin which is specifically toxic to ruminant neutrophils and reduces phagocytosis by inducing neutrophil apopotosis -> liver abcesses (hepatic necrobacillosis; see image)
Persistence after phagocytosis:
Due to ability to prevent lysosomal fusion- prevention of fusion of lysosomes containing toxic chemicals within macropahge and hence preventing destruction of pathogen
very common in Mycobacteria- e.g TB
Isolation:
Pyogenic bacteria, Strep/Staph spp., “hide” themselves within lakes of pus
Also affects antibiotic penetration; i.e. lancing and flushing cat bite abscesses far better than systemic antibiotics.
Unresponsiveness:
Certain foreign materials cannot be phagocytosed and/or broken down
Plant material, suture materials, silicosis (horses that live on sand), asbestos, atherosclerosis. e.g stick injury
Disease of immunity:
Autoimmunity- arthrytis
Leukocyte defects
Macrophages
- Quickly sense acute inflammation.
2.Migrate in response to chemotaxins.
3.Remove and kill microbial agents by phagocytosis.
4.Process antigens for presentation to effector cells of the adaptive immune response.
5.Facilitate angiogenesis and remodel the ECM.
Abscesses form due to …
Production of myeloperoxidase by neutrophils which themselves also undergo necrosis, resulting in liquefaction and pus
Rabbits and birds lack myeloperoxidase, resulting in an inability to form pus
Chronically, fibroblasts produce collagen and extracellular matrix proteins to wall off the area = fibrous capsule
Granulomatous inflammation
occurs when the inciting agent cannot be removed and is largely
mediated by macrophages which may become multinucleated or epithelioid
Granulomatous inflammation can be :
Nodular = (tuberculoid) granulomas
Mycobacterium bovis
Diffuse = lepromatous
Eosinophilic granuloma
Mycobacterium leprae
repair and Healing
Repair and healing are defined loosely as restoration of tissue architecture and function after an injury
Repair (parenchymal and connective tissues)
Healing (surface epithelia)
what are the two mechanism of healing and repair
REGENERATION: some tissues are able to replace damaged components and essentially return to a normal state
occurs by proliferation of cells that survive the injury and retain the capacity to proliferate
In some cases, tissue stem cells may contribute to restoration of damaged tissues (mammals have limited capacity to regenerate damaged tissues/organs)
i.e. in the rapidly dividing epithelia of the skin and intestines and in some parenchymal organs, notably the liver.
Requires an intact basement membrane
CONNECTIVE (FIBROUS) TISSUE DEPOSITION
Occurs when injured tissue incapable of complete resolution or if supporting tissue structure is severely damaged
May result in scar formation – not normal but provides enough structural stability that the injured tissue is usually able to function
Fibrosis: describes the extensive deposition of collagen that occurs in the lungs, liver, kidney, etc. as a consequence of chronic inflammation or in the myocardium after extensive ischemic necrosis (infarction)
healing and repair mechanism- REGENERATION:
some tissues are able to replace damaged components and essentially return to a normal state
occurs by proliferation of cells that survive the injury and retain the capacity to proliferate
In some cases, tissue stem cells may contribute to restoration of damaged tissues (mammals have limited capacity to regenerate damaged tissues/organs)
i.e. in the rapidly dividing epithelia of the skin and intestines and in some parenchymal organs, notably the liver.
Requires an intact basement membrane
healing and repair mechanism- CONNECTIVE (FIBROUS) TISSUE DEPOSITION
Occurs when injured tissue incapable of complete resolution or if supporting tissue structure is severely damaged
May result in scar formation – not normal but provides enough structural stability that the injured tissue is usually able to function
Fibrosis: describes the extensive deposition of collagen that occurs in the lungs, liver, kidney, etc. as a consequence of chronic inflammation or in the myocardium after extensive ischemic necrosis (infarction)
Fibrosis:
describes the extensive deposition of collagen that occurs in the lungs, liver, kidney, etc. as a consequence of chronic inflammation or in the myocardium after extensive ischemic necrosis (infarction)
Healing and scar formation
Macrophages play a central role in repair by-
clearing offending agents and dead tissue,
providing growth factors for proliferation of cells
secreting cytokines that stimulate fibroblast proliferation and connective tissue development
Repair begins within 24 hours after injury with emigration of fibroblasts and induction of fibroblast and endothelial cell proliferation.
Angiogenesis (formation of new blood vessels) – supplies nutrients/oxygen for repair; vessels are leaky because VEGF (GF that drives angiogenesis) increases vascular permeability; also due to incomplete interendothelial junctions
Formation of granulation tissue – consists mainly of fibroblasts and new capillaries in a loose ECM often admixed with inflammatory cells (mainly macrophages); progressively invades site of injury; amount formed depends on size of tissue deficit and intensity of inflammation
Remodelling of connective tissue (produces stable fibrous scar) – process of maturation of the connective tissue. The amount increases gradually leading to reorganisation and formation of a scar.
Angiogenesis
Angiogenesis is the formation of blood vessels
Can occur via-
proliferation of endothelial cells from existing blood vessels near the site of injury
from bone marrow endothelial precursor cells (EPCs)
Hypoxia is the major trigger
The renal corpuscle is the
glomerulus and Bowman’s capsule
The main driving force for filtration in the glomerulus is
the glomerular capillary hydrostatic pressure.
As blood travels through the glomerular capillary, a large proportion of the fluid component of the plasma is forced across the capillary wall, whereas the plasma proteins are largely retained in the
capillary lumen.
The urinary filtration barrier comprises
Fenestrated endothelium of glomerular capillaries
Glomerular basement membrane
Foot processes of the podocytes
Renin-angiotensin-aldosterone system
Renin-
Released by juxtaglomerular apparatus in response to low blood pressure and flow to the kidney
Transforms angiotensinogen (made by the liver) to angiotensin I
Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE – made by the lung)
Angiotensin II-
Acts directly on vessels to result in vasoconstriction-> increase blood pressure
Acts on the adrenal gland to produce aldosterone-> kidney tubules resorb salt and water
Renin
Released by juxtaglomerular apparatus in response to low blood pressure and flow to the kidney
Transforms angiotensinogen (made by the liver) to angiotensin I
Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE – made by the lung)
Angiotensin II
renin Transforms angiotensinogen (made by the liver) to angiotensin I
Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE – made by the lung)
Acts directly on vessels to result in vasoconstriction-> increase blood pressure
Acts on the adrenal gland to produce aldosterone-> kidney tubules resorb salt and water
renal tubules
The tubules are responsible for reabsorption of water, glucose electrolytes and bicarbonate
The tubules therefore are responsible for urine concentration
The kidney is responsible for
Eliminating waste-
Urine formation
Acid base regulation-
Resorption of bicarbonate
Conservation of water-
ADH/vasopressin
Maintenance of electrolyte balance-
Potassium, sodium and chloride resorption and excretion
Other metabolic and endocrine functions-
Production of EPO for haematopoiesis
Vitamin D and calcium regulation
Maintenance of blood pressure
Kidney injury – toxins affecting tubules
Directly toxic - aminoglycosides
Toxic metabolites – ethylene glycol
Kidney injury – toxins affecting tubules
Directly toxic - aminoglycosides
Toxic metabolites – ethylene glycol
Kidney injury – ischaemia
The kidney can cope with low blood pressure and/or reduced renal blood flow to a point, thanks the R-A-A system
Sudden acute drops in flow to the kidney or prolonged low blood pressure are less manageable
Acute-
Sepsis
Heatstroke
Thromboembolism
Acute haemorrhage or shock
Chronic-
Congestive heart failure
Some drugs can directly affect flow to the kidneys-
Prostaglandins and COX are involved in the normal maintenance of renal blood flow
COX inhibitors such as NSAIDs will thus cause ischaemic necrosis by reducing blood flow via vasconstriction -> Renal medulla/crest necrosis
Hydronephrosis
refers to dilation of the renal pelvis, which fills within urine.
Typically due to downstream blockage
Increased pressure in the renal pelvis results in no where for urine to go and glomeruli continue to “make” urine
-> urine is forced into renal interstitium -> collapse of interstitial vessels -> hypoxia -> repair by fibrosis
Acute renal failure
Renal failure occurs when one or more of the 5 functions is impaired.
The kidney can function appropriately, with little to nothing clinical apparent, with up to 75% of functional mass lost.
Acute renal failure can be pre-renal (reduced blood flow), intra-renal (tubular necrosis) and post-renal (urinary obstruction)
Results in;
Failure to eliminate waste- Azotaemia
Inability to maintain acid-base haemostasis- Metabolic acidosis
Inability to maintain blood volume and pressure- Hypertension
Acutely injured kidneys are generally enlarged-
Inflammatory cells
Oedema
Uraemia
The systemic changes associated with severe azotaemia
Uraemia is a clinical syndrome
Whilst in clinical pathology we associate elevated levels of urea and creatinine with renal failure, in reality, over 90 toxins that would otherwise be filtered by the kidney build up in the blood
Uraemic toxins damage tissue by- Endothelial damage
Also, some of these toxins are leached into saliva and gastric secretions-> metabolised to ammonia -> caustic ulceration of mucosa (tongue, stomach, colon)
Chronic renal failure
When one part of the nephron is damaged, eventually the rest of the nephron follows
Replaced by fibrosis
Animals with chronic renal failure are azotaemic and will eventually become uraemic
Other findings-
Hypertension
Non-regenerative anaemia
Hypokalaemia
Calcium deposition in soft tissues
renal seconday hyperparathyroidism
Maintenance of calcium is exceptionally complex
Kidneys, gut, bone, thyroid and parathyroid glands involved
The role of the kidney is three-fold
Resorption of calcium
Phosphate excretion
Activation of vitamin D
Failing kidneys result in
Reduced calcium
Increased phosphate
Inactivated vitamin D- Less calcium absorbed from intestine
Chronic renal failure ultimately results in renal secondary hyperparathyroidism
Due to low calcium, the parathyroid glands become hyperplastic and produce more parathyroid hormone
As there is no other way in the animal of increasing plasma calcium, calcium is resorbed from bone
This results in weak bones, replaced by fibrosis = rubber jaw
Also the combination of high phosphate and acidosis means calcium is deposited in soft tissues, particularly stomach, kidney and pleura
Congenital disorders of the kidney
Aplasia = never formed
Hypoplasia = small
Dysplasia = abnormally formed
Renal dysplasia-
Progressive juvenile nephropathies
Polycystic kidney disease
Heritable-
Progressive juvenile nepropathies
Typically issue is initially in the glomeruli
Due to collagen defect
Samoyeds
PKD-
Persian cats, English Bull Terriers = PKD 1;
Autosomal dominant
Westies, Cairn terriers, sheep = PKD 2;
Autosomal recessive
Neoplasia of the kidney
From within – typically unilateral and singular
Renal cell carcinoma
Urothelial cell carcinoma
From without – typically bilateral and multiple
Lymphoma
Endocrinopathies are due to
An under or overproduction of hormones
An inability to respond to hormone production.
Exogenous hormone administration.
Production of hormone-like substances from certain cancers
Underproduction of hormones is due to-
Immune-mediated destruction of the endocrine organ.
Upstream endocrine organ destruction.
The inability to produce a hormone due to a nutritional deficiency.
Typically, overproduction is due to hyperplasia or neoplasia.
morphology of leptospira
Family: Spirochaetaceae- Leptospira, Borrelia, Treponema
Gram-negative-like, slender, motile, flexous bacteria.
Helically-shaped / Spiral bacteria.
Genomospecies-
64 genomospecies (Pathogenic, intermediate and saprophytic species)
37 pathogenic genomospecies (P1 and P2 subclades)
27 saprophytic subclades
Serovars-
Based on lipopolysaccharide (LPS) carbohydrate moiety difference
Pathogenic leptospiral serovars
~250
Saprophytic leptospiral serovars
~60
Serogroups- Group of antigenically similar serovars
Leptospiral Outer Membrane Proteins
The outer sheath is a multilayered membrane which surrounds the protoplasmic cylinder.
Complement evasion, Phagocytosis evasion
Adhesion Extracellular matrix binding properties (plasminogen, lamin binding)
Iron Uptake, Toxin production
Serum resistance, Nutrient importation, Exporting bactericidal and toxic agents
clinical presentation of leptospirosis
Subclinical Form-
Clinically inapparent
Responsible for maintenance of infection due to chronic shedding in some cases
Peracute Form-
Death
Short clinical presentation of shock and DIC
Acute Form-
Fever, vascular injury, haemorrhage, anorexia, shock, signs of renal failure, jaundice, diarrhea, muscle tenderness, reluctance to move and death
Acute kidney injury, liver impairment and/or LPHS
Chronic Form-
Multisystemic failure, chronic hepatitis, chronic interstitial nephritis/renal damage, anterior uveitis
Large ruminants
Cattle maintain: L. serovar Harjo
Incidental infection with Icterohaemorrhagiae, Canicola, Hebdomadis, Sejroe, Pyrogenes, Autumnalis, Australis, Javanica, Tarassovi, and Grippotyphosa serogroups
Clinical presentation: Pyrexia, hemolytic anemia, hemoglobinuria, jaundice, drop in milk production, abortion, stillbirth, death
Pigs-
Maintained serovars: Pomona, Australis, and Tarassovi group
Incidental infection: Grippotyphosa, Icterohaemorrhagiae, and Canicola serogroups.
Dogs-
Fever, vascular injury, haemorrhage, anorexia, shock, signs of renal failure, jaundice, diarrhea, muscle tenderness, reluctance to move and death
Maintained serovars: Canicola serovar
Incidental infection: Icterohaemorrhagiae serogroup, Grippotyphosa and Pomona (L2 to L4 vaccines)
Geographical difference in predominant serovars and L4 vaccines
Leptospirosis: Invasion and pathogenesis
LEPTOSPIRA – contaminated surfaces, direct contact with infectious agents come into contct with SKIN and MUCOUS MEMBRANE (broken epithelium)
Entry and multiplication in blood stream
Haematogenous dissemination – bacteraemic phase (leptospiraemia)
Dissemination to all the body organs and tissues- Endothelial damage (vasculitis)
Resulting vascular damage leads to localized ischaemic necrosis in affected tissues- Acute
Febrile Illness
Multiorgan Involvement:
Tubular necrosis
Hepatocellular injury
Pulmonary damage
Placentitis
Myositis
Tissue localisation
Chronic presentation and Multiorgan
Organ failure
Leptospirosis diagnostic approaches
Antibody detection-
Microscopic agglutination test (MAT)
ELISA
Point of care assays: Snap Lepto (IDEXX), Witness Lepto (Zoetis)
Antigen detection:
Bacterial Culture
Darkfield Microscopy
Molecular Diagnosis and typing: PCR (Real time PCR and conventional PCR), MLST, Gene sequencing
Other diagnostic processes include: immunofluorescent antibody (IFA), immunohistochemistry,
Diagnostic Complexities of leptosporosis
Fastidious growth of leptospira in culture- Requires specialized media for isolation and identification
Takes about 13 weeks (3months) for confirmation
MAT limitations- Subjectivity of interpretation
Cumbersome, requires technical expertise, risk of exposure
Complex leptospiral taxonomy- Serovar, serogroup and genomospecies confusion
Differentiating Infected from Vaccinated Animals (DIVA)- Vaccination confounds serology titre detection
Phase of infection and diagnostic detection- Diagnosis best with an idea of the phase of infection
Treatment interference with sample quality- Antibiotics administration interferes with PCR and culture
Renal Leptospirosis Lesions gross lesions
Pale, mottled/petechiated kidney
Subcapsular and cortical haemorrhage
Enlarged kidney with focal white spotting/necrotic streaks in renal cortex
Haemoglobinuric/bilirubinuric nephrosis
Chronic renal injury resulting in shrunken or enlarged kidney
generalised gross leptospirosis lesions
Jaundice
Haemorrhage (petechial and ecchymotic)
Ascites
Fibrin thrombi
Pleural and pericardial effusion
Haemorrhagic gastroenteritis
Wet, mottled, heavy and dark red lungs (LPHS)
Friable liver
Renal Leptospirosis Lesions histopathological pathology
Tubular necrosis-
Hypoxia and Ischaemia
Accumulation of intratubular haemoglobin and bilirubin
Mixed inflammatory interstitial nephritis-
Occurs secondary to tubular necrosis
Suppurative and lymphoplasmacytic infiltrates
Chronic intersitial nephritis-
Mononuclear infiltration
Interstitial fibrosis due to chronic injury
Tubular atrophy
Leptospires detection using silver staining
geeral Leptospirosis Lesions histopathological pathology
Liver-
Coagulative hepatic necrosis
Periportal hepatitis (neutrophilic)
Intrahepatic bile stasis
Muscles-
Necrotising neutrophilic myocarditis
Myonecrosis and myositis
Lungs-
Intraalveolar haemorrhage
Pneumocyte necrosis
Pulmonary oedema
Clinical Categories of Laminitis
Multifactorial disease process, with common end-point of laminar degeneration
Endocrinopathic-
Insulin dysregulation (Equine Metabolic Disease)
Equine Pituitary Pars Intermedia Dysfunction (PPID)
80% of cases of laminitis have underlying endocrinopathic disorders
Inflammatory-
Severe infection (sepsis, colitis, endometritis)
Traumatic-
Excess weight bearing on one limb (contralateral limb laminitis)
Pituitary pars intermedia dysfunction (PPID)
(Equine Cushing’s Disease)
Age related degenerative condition- Condition of older horses (average age 19yo)
Rarely diagnosed in younger horses (<10yo)
No sex predilection
Ponies more likely to be affected than horses
Loss of dopaminergic inhibition
Hypothalamus unable to regulate pars intermedia of pituitary gland
Hypertrophy / hyperplasia of PI
Increase production of many hormones from PI which have wide array of effects on body
Functions of cortisol-
Increase gluconeogenesis
Decrease glucose utilisation
Increase glycogen deposition in liver
Decrease protein synthesis in muscles
Increase fat breakdown and redistribution
Decrease production and function of WBCs (immunosuppression)
Decrease cell division
Clinical Signs
Lethargy / Poor performance
Coat abnormalities
Loss of seasonal haircoat shedding
Skeletal muscle atrophy
Rounded abdomen
Abnormal sweating (↑ or ↓)
Polyuria/polydipsia (↑ urinating/drinking)
Regional adiposity
Absent reproductive cycle/Infertility
Laminitis
Susceptible to other infections
Blood Tests-
Basal ACTH assay- Most commonly used test in UK
TRH-Stimulation test- 2nd line test for borderline cases
PPID- Management / Treatment
Focus on preventative medicine (PPID cases susceptible to infections)-
Regular dentistry
Excellent foot care
Clipping and supporting thermoregulation
Optimising diet and management conditions
Diligent parasite control
Treatment-
Pergolide (Prascend) is drug of choice for PPID
Can take time to establish effective dose – close monitoring
High doses may be associated with loss of appetite
Equine Metabolic Syndrome
Clustering of endocrine and metabolic abnormalities associated with the development of laminitis in equidae
Obesity or Regional adiposity
Insulin Dysregulation
Hypertriglyceridaemia
Seasonal Hypertension
Systemic inflammation
Disease of domestication and modern husbandry practices
Energy imbalance; calorific excess and under-activity
Abnormal feeding patterns & preconception of normal BCS
Inappropriate feeding for level of energy expenditure
Genetic phenotype for enhanced metabolic efficiency predisposes to obesity
Periods of food shortage lead to selection of genes which improve metabolic efficiency
Clinical Signs-
Laminitis
Obesity (general, regional)
Resistance to weight loss
Lethargy/poor performance
Swellings around groin
Some EMS cases are not obese
Insulin testing-
Fasting insulin concentration can confirm hyperinsulinemia where present
Post-prandial Insulin-
Measure serum insulin 2h after feeding a single dose of glucose (1g/kg)
INSULIN DYSREGULATION IS THE UNDERPINNING COMPONENT OF THE MAJORITY OF LAMINITIS CASES
PPID Insulin Resistance
PPID cases can demonstrate a degree of Insulin Dysregulation
Cortisol antagonises the actions of insulin
Some POMCs released in PPID act as insulin like hormones
PPID may only serve to exacerbate pre-existing hyperinsulinaemia
Remains an Important consideration / rule-out in horses with Insulin Resistance
foetal membranes
chorion
yolk sack
amnion
allantois
diffuse placenta
points of attachment are diffuse
almost all of allantochorin involved (horses, pigs)
discoid placenta
1-2 points of contact in a disc shape (rodents)
cotelydonary placenta
multiple discrete poitns of attachment(cotelydons) that interact with endometrium (caruncles) to form placentomes (ruminants)
zonary placenta
band of tissue forming point of attahcment(dogs and cats)
Non-infectious Causes of abortion
Cattle: ~ 50%
Sheep: ~ 40%
Pigs: ~ 60-70%
Horses: ~ 60-70%
Causes:
Maternal and foetal stress
Dystocia
Appearance-
Mummified foetuses
Still-birth
Infectious Causes of abortion
Bacteria, viruses, protozoa, fungi-
Can affect dam, placenta, foetus or a combination
Primarily haematogenous
Except in horses where majority of bacterial and fungal abortions are ascending
True venereal infections include-
Tritrichomonas foetus
Campylobacter foetus venerealis
Appearance-
Mummified or macerated foetus
Placental changes
Mummification of the ferus
Mostly in multiparous animals (most commonly sows)
No bacteria
Foetal skin is developed enough to withstand autolysis
Absorption of placental and foetal fluids
No odour
Closed cervix
Causes-
Genetic
twinning (mare)
viral (BVD, porcine parvovirus, canine herpesvirus) ,
protozoan infections (Neospora, ovine toxoplasmosis)
placental insufficiencies
Further diagnostics on a mummified foetus not possible
Usually no effect on subsequent breeding
Maceration f the fetus
Foetus is liquified
Foetid smell
Bones will remain
Bacterial cause-
Endometritis
Open cervix
Emphysema of the fetus
Associated with-
Protracted dystocia
Late expulsion of dead foetus
Putrefactive ascending bacteria- e.g. clostridial organisms)
Foul smell and gas under skin (crepitant)
Advanced uterin lesions and dam may die due to toxaemia
occult causes of abrotion in cattle
Salmonella and other bacterial and fungal contents can be cultured from foetal stomach content
Chlamydia and lepto difficult to culture so-
MZN stain of foetal stomach content or PCR for chlamydia
Foetal kidney PCR for lepto
Histopathological +/- IHC of foetal tissues
Coxiella also tested for with MZN before proceeding with sheep abortions due to zoonotic risk
Brucella testing to maintain Brucella-free testing also MZN
Histopathological +/- IHC of foetal tissues-
Brain, liver, lung AND PLACENTA
Serology – dam blood and foetal fluid
Perinatal mortality
Perinatal mortality may be defined as death of the foetus or perinate before, during or within 48 h of calving at full term (> 260 days in cattle)
Includes both stillbirth and early neonatal mortality
As well as the previously discussed samples, examination of the foetal thyroid gland for-
absolute goitre (thyroid enlarged relative to a criterion-referenced threshold thyroid weight, e.g. > 30 g)
or relative goitre (thyroid enlarged relative to a criterion-referenced threshold thyroid g: kg ratio with body weight, e.g. > 0.80)
and submission of a fresh (I2 content) and formalinised lobe (histopathology) will detect dietary iodine imbalance.
Where selenium deficiency is suspected a fresh sample of the foetal liver preferably or kidneys should be submitted.
assessing stress through the adrenal activity in vet concervation
elevated or low glucocorticoid response can indicate and animal is not maintianing hoemostasis
gcs produced by adrenal gland in response to stimuli
facilitate mobilization of ennergy
seen in response to mating and agression stimuli
can be an indicator of hown individula is coping with stress
elevated levels not always bad:
increase during breeding, ovulation, pregnancy, partuition and lactation
can be natual
types of concervation in vet concervation
synthetic steriod hormones- false pregnancy (progesterone +/- estrogen)
GnRH agonists- chemical castration- deslorelin, leuprolide acetate
immunocontraception- Vaccine response- PZP, GnRH vaccine
Germ Cells
cells within the testes
Spermatogonia are the sole proliferative cell population within the seminiferous epithelium and in residing outside of the protective “blood–testis barrier” formed by tight junctions between Sertoli cells.
Spermatocytes are the largest germ cells, are mostly tetraploid, and represent the meiotic phase of germ cell differentiation.
Spermatids, round and elongating, are the haploid products of meiotic division.
With maturation, which involves progressive loss of cytoplasm and organelles, spermatids are dependent on the supporting Sertoli cell for successful terminal differentiation and release.
Due to DNA exchange during the process of meiosis, spermatids and spermatozoa become antigenically foreign, and these “immune-privileged” cells (due to their location within the blood–testis barrier) incite an inflammatory response when the seminiferous epithelium is disrupted.
Sertoli Cells
cels within the testes
Sertoli cells are large, post-proliferative cells that are essential to spermatogenesis.
They serve multiple complex roles, including simultaneous support of synchronous differentiation among several cohorts of germ cells of differing maturity, maintenance of the blood–testis barrier, secretion of seminiferous fluid, release of matured spermatids, and phagocytosis of residual bodies and apoptotic germ cell remnants.
Leydig (Interstitial) Cells
cells within the testes
Intratesticular androgen levels, crucial to germ cell maintenance, are sustained by Leydig cells.
These endocrine cells are outside of the protective blood–testis barrier.
Mesenchymal tissues
Mesenchymal tissues can be part of many organs and help to give the organs shape and strength. The basic component of many soft tissues or supporting structures is the substance collagen. Collagen is a protein that is woven from fibrils that give it both strength and resilience (the ability to bend or bounce back).
Mesoderm
Supporting cells-
Fibroblasts -> collagen
Endothelia
Bone
epithelial tissues
Epithelial tissues are widespread throughout the body. They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.
All endoderm and some ectoderm and mesoderm
Cells form bulk of parenchyma of organ, glands or line organs
Hepatocytes
Skin
GIT
Bladder
Cell-to-cell and cell-to-basement membrane adherence
Sexual development occurs in three steps:
The establishment of chromosomal/genotypic sex
The determination of gonadal sex
The development of phenotypic sex
Chromosomal/genotypic sex
Determined at fertilization – XX or XY
zz (male)/zw (female or birds
Rarely, aneuploidy (diffretn number of sexchromosomes )can occur resulting in XXX, XXY (Kleinfelter-like syndrome), or X_ (Monosomy X/Turner-like syndrome)
aneuploidy
Rarely, aneuploidy (diffretn number of sexchromosomes )can occur resulting in XXX, XXY (Kleinfelter-like syndrome), or X_ (Monosomy X/Turner-like syndrome)
male tortushell cats commonly are xxy
In the case of cats with Klinefelter syndrome, the extra X chromosome is commonly associated with a failure of the testes to function properly, which explains why male tortoiseshell cats are usually sterile.
The partial or complete loss of one X chromosome in humans causes Turner syndrome (TS), which is accompanied by a range of physical and reproductive pathologies.
Reported in a pig:
Short stature, micrognathia, and skeletal abnormalities in the limbs.
Phenotypically female but did not exhibit an estrous cycle, even after reaching the age of sexual maturity, and showed no ovarian endocrine activity.
An autopsy at 36 months revealed an undeveloped reproductive tract with ovaries that lacked follicles.
Gonadal sex
Determined by a variety of genes
Primarily involves SRY – which is on Y chromosome and not X chromosome.
Female:
XX chromosomal sex lacks the SRY and testis-determinating factors
WNT4 is important and upregulates folistatin (FST) and DAX1; it also inhibits SOX9 (a male specific gene)
FOXL2 and BMP2 also are important in upregulation of FST
Wolffian (mesonephric - male) ducts regress in the absence of SRY gene product
Outer cortical layer of bipotent gonad becomes ovarian tissue first -ovotestes are usually ovarian tissue on the periphery with varying amounts of testicular tissue in the medulla
Male:
In the presence of SRY, SOX9 expression is increased, promoting the testicular pathway and blocking the ovarian pathway
SRY is also important in early Sertoli cell differentiation
Phenotypic sexual development
Driven by gonadal factors
A functional testis is critical to male phenotypic development
Female tubular and external genital development form from paramesonephric (Mullerian) ducts – will develop in theabsenceof hormones
The presence oftestosterone and anti-Mullerian hormone (AMH) cause regression of paramesonephric ducts and development of mesonephric (Wolffian) ducts into male genitalia and accessory sex glands
AMH is produced by Sertoli cells and testosterone is produced by interstitial (Leydig) cells
Ovotestis usually results in varying degrees of masculinization of the tubular and external genitalia – e.g. clitoral hypertrophy, hypospadias
The oviduct has been injected with India ink. The uterine horns are on the left of the image. Histopathology of the
structure within the broad ligament reveals simple tubular structures lined by low columnar to cuboidal cells sometimes featuring cilia and a lumina expanded by proteinaceous fluid, supported by a smooth muscle wall.
What is the circled structure?
a.Ovotestis
b.Mesonephric duct cyst
c.Paramesonephric duct cyst
d.Ectopic pregnancy
e.Cystic epoophoron
Mesonephric duct cyst
A type of paraovarian cyst
The mesonephric duct (also known as the Wolffian duct, archinephric duct, Leydig’s duct or nephric duct) isa paired organthat forms during the embryonic development of humans and other mammals and gives rise to male reproductive organs.
During the early stages, male embryos and female embryos contain the same structures and cannot be differentiated. Paired mesonephric (Wolffian - male) ducts and paired paramesonephric (Müllerian - female) ducts form de novo from longitudinal folds along the lateral inner abdominal wall
The uterine tubes, uterine horns, body, cervix, and cranial vagina develop from the paramesonephric duct,
The mesonephric tubes become the rete and contribute to the sex cords of the ovary.
Normally the ducts of the opposite sex regress; however, their embryonic remnants are frequently encountered in otherwise normal adult animals, appearing as grossly detectable cystic structures in or near the ovary, uterus, cervix, or vagina.
Cystic remnants of the mesonephric duct system can sometimes be found in the mesosalpinx, where they may vary in size from a few mm to 20 mm or more. Large cysts can be mistaken for ovaries or ovarian structures during palpation but are generally of no functional significance. Cystic remnants of the mesonephric duct may also be found in the broad ligament of the uterus, where they are also of no consequence, or under the mucosa of the caudal vagina in a ventrolateral position, where they are known as Gartner’s duct cysts.
mesonephric duct
The mesonephric duct (also known as the Wolffian duct, archinephric duct, Leydig’s duct or nephric duct) isa paired organthat forms during the embryonic development of humans and other mammals and gives rise to male reproductive organs.
During the early stages, male embryos and female embryos contain the same structures and cannot be differentiated. Paired mesonephric (Wolffian - male) ducts and paired paramesonephric (Müllerian - female) ducts form de novo from longitudinal folds along the lateral inner abdominal wall
The uterine tubes, uterine horns, body, cervix, and cranial vagina develop from the paramesonephric duct,
The mesonephric tubes become the rete and contribute to the sex cords of the ovary.
Normally the ducts of the opposite sex
Paraovarian cysts
mesonephric duct
paramesonephric duct cyst- on fibrae of fallopean tubes, can be on foals
cystic epoophoron
Paramesonephric duct aplasia
uterine horn hasnt formed properly
common in cattle
can result in accuulation and infections
Pseudohermaphroditism
Pseudohermaphroditism is a condition in which an individual has matching chromosomal and gonadal tissue (ovary or testis) sex, but mismatching external genitalia.
Male pseudohermaphrodite
The most common intersex condition
XY, SRY +ve
Testicular tissue in the abdominal cavity or beneath the skin in the scrotal region, and external genital organs that resemble those of females.
Miniature Schnauzers, Basset Hounds, and rarely, Persian cats may present with pseudohermaphroditism when affected by persistent paramesonephric (Müllerian) duct syndrome.
Female pseudohermaphrodite
Female internal reproductive organs and typical female karyotype (XX, SRY-ve), but exhibit varying degrees of external physical male genitalia.
Most cases of female pseudohermaphroditism result from administration of steroids to pregnant bitches during critical stages of foetal development, inducing virilization of female foetuses
can be caused by steroids used on the pregnant mother
can also be genetic
Freemartinism
Freemartinism syndrome is well known in cattle but has also been described in sheep, goats, and camelids.
It causes sterility in females born co-twin to males; ~92% of all heifers born co-twin to bull calves are sterile.
These animals exhibit varying degrees of female-to-male sex reversal of the internal and external genitalia.
The tubular genital organs in affected animals range from cordlike bands to near-normal uterine horns.
Freemartins have a short vagina that ends blindly without communication with the uterus. The cervix is absent.
the shared blood supply between the twins will allow the hormaones produced by the male to affect the female
The most common congenital abnormality of the ovary is
ovarian dysgenesis or ovarian hypoplasia.
True agenesis is rare.
ovarian dysgenesis
Ovarian dysgenesis has been described in several domestic animal species and has been associated with various chromosomal abnormalities (monosomy X or Turner syndrome, trisomy XXX, or Klinefelter syndrome XXY).
The ovaries are very small and lack follicular activity.
the complete or nearly complete absence of ovarian tissue in phenotypic females.
Ovarian cysts
A wide variety of cysts occur in and around the ovary.
Paraovarian cysts are common in the mare
Cysts that occur within the ovarian parenchyma include cysts derived from:
anovulatory Graafian follicles (luteal and follicular cysts)
cystic corpora lutea
cystic rete ovarii- The rete ovarii, the homolog of the rete testis, is present in the hilus of all ovaries.
cysts of the subsurface epithelial structures
Some may interfere with normal reproductive cyclicity, but most are innocuous.
Luteal and follicular cysts both are derived from anovulatory Graafian follicles and differ only in the degree of luteinisation
Cysts derived from anovulatory Graafian follicles are most common in the cow and sow, but also occur sporadically in the bitch and queen. They often cause altered reproductive activity through secretion of steroid hormones. Affected animals, especially bitches, may show marked manifestations of hyperestrinism, such as altered reproductive behavior, anemia, and hemorrhagic diathesis. In the cow and sow they may be associated with anestrus, persistent estrus, or nymphomania
Cystic corpora lutea are essentially a variation of a normal luteal structure and the animal may be pregnant.
Cystic rete ovarii- Most common in the guinea pig
Cystic subsurface epithelial structures (cystic SES) -
Most common in the bitch.
The modified peritoneal cells covering the surface of the ovary of the bitch normally extend into the ovary a short distance, where they are arranged as small, single, epithelial lined cavities called “subsurface epithelial structures” or SES.
Their importance is 2-fold. They frequently give rise to single, or more commonly, multiple cysts extending along the ovarian surface, and SES often undergo papillary hyperplasia and neoplastic transformation.
Neoplasms of the SES are usually adenomas, but carcinomas do occur.
bilateral allopecia on the guinea pig
Ovarian cysts are commonly reported in guinea pigs
75.6% in animals >6 years
In one paper only arose from rete ovarii but in others from Graffian follicles
Rete ovarii should not produce sex hormones, while follicular cysts may be steroidogenic
Resulting in typical clinical signs such as
bilateral non-pruritic alopecia
rule out hyperT and HAC
clitoral hypertrophy
nipple hyperkeratosis
behavioural changes
Cystic ovarian disease in cattle
Follicular and luteal
During normal proestrus, regression of the CL coincides with development of a selected follicle, while the growth of any additional follicles is inhibited. In animals developing COD, ovulation fails to occur and the dominant follicle continues to enlarge.
Follicular-
Frequent, intermittent oestrus
Bull-like exaggerated sexual behaviour-, Mounting, Pawing the ground, Bellowing
Or sexually quiescence/anoestrous
Grossly, follicular cysts resemble enlarged follicles, generally defined as varying in size from 25-60 mm in diameter.
Capable of steroidogenesis-products vary from oestrogens to progesterone to androgens.
Luteal-
Anoestrus
Thicker, yellow (luteinized) wall
Primarily produce progesterone
Ovarian tumours
Surface epithelium and SES-
Papillary and cystic adenomas
Papillary adenocarcinomas
Sex cord stromal tumours-
Granulosa cell tumours
Thecoma, luteoma
Germ cell tumours-
Dysgerminoma
Teratoma
Gonadal stromal tumours
teratoma
a germ cell tumour with 2 out of the three cell types- ectoderm, mesoderm, endoderm
Endometrial hyperplasia
In the bitch, the normal oestrous cycle includes differentiation and proliferation of endometrial glands.
This is under the influence of oestrogen during proestrus, with more extensive proliferation during oestrus and metestrus/dioestrus under the influence of progesterone.
Endometrial hyperplasia is common in domestic canines, often involves cystic distension of endometrial glands (cystic endometrial hyperplasia, CEH).
Exogenous sources of progesterone can be found in megestrol acetate, etc.
Chronically hyperplastic endometrial glands lead to the gross accumulation of mucoid fluid = mucometra and hydrometra
metabolic issue
There is debate among authors whether cystic endometrial hyperplasia (CEH) and pyometra are linked, it is currently thought that prolonged exposure to high levels of progesterone cause endometrial gland proliferation which may increase susceptibility of the uterus to infection.
E.coli
infection in the uterus in the cow
Metritis in the cow is typically seen post partum - <2weeks
assosiated with Dystocia
Polymicrobial as opposed to just e.coli in bithces
Acute puerperal metritis refers to a severe postpartum uterine infection that results in systemic signs of toxaemia.
Clinical metritis is used as a general term for postpartum uterine infections, which may not be associated with systemic signs.
Post-partum metritis in sheep and goats is often due to Clostridium tetaniandC perfringens
contageous equine metritis
CEM, caused byTaylorella equigenitalis, a microaerophilic gram negative coccobacillus, is ahighly contagiousvenereal diseaseofmaresthat is characterized by endometritis, transient infertility, and rarely abortion
Stallions do not develop clinical disease, but can transmit the organism; recovered mares can harbour the organism for several months and are an important reservoir
Infectious endometritis – similar clinical, gross, and histologic changes; bacteriologic culture to differentiate:
Beta-hemolytic streptococci (equissp.zooepidemicus: beta-Strep.)
Klebsiella pneumoniae
Escherichia coli
Uterine defences to infection
Infection of the uterus risks infertility therefore the uterus has many ways to prevent.
The vast majority of infections are ascending therefore majority of innate defences focussed on keeping things out, creating a sterile environment for the developing foetus.- Cervix
However must also have the ability to allow in antigenically stimulating sperm and be immunotolerant to the foetus.
Mucosal immunity- Locally produced IgA, Stops attachment of bacteria to the uterine wall
Hormonal changes affecting immunity-
Oestrogen stimulates neutrophils, macrophages and T-cells
Progesterone down-regulates the immune response
Endometriosis
Endometriosis is a chronic disease affecting 5–10% of women of reproductive age
Asymptomatic in a minority of the cases, the main symptoms and signs include chronic pelvic pain, dysmenorrhea, pain during intercourse, abnormal uterine bleeding and infertility.
Characterized by ectopic endometrial-like tissue (glands and stroma) that induce a chronic inflammatory response, adhesions, and scar tissue.
NHPs also develop endometriosis
neoplasia of the uterus
Uterine endometrial adenocarcinoma
The most common neoplasia of the rabbit reproductive tract and probably the most common neoplasia of any body system of female rabbits
Carcinoma = malignant
80% will metastasize
lungs
Leiomyoma/leiomyosarcoma-
Tumour of smooth muscle
Leiomyomas of genital origin are among the most frequently encountered neoplasms of the female reproductive system in almost all domestic animals, including elephants
Leiomyoma/leiomyosarcoma
Tumour of smooth muscle
Leiomyomas of genital origin are among the most frequently encountered neoplasms of the female reproductive system in almost all domestic animals, including elephants
routs of infection for mammary glands
Ascending most common
Systemic infections less common but noteworthy are:
Mycoplasma
Caprine arthritis and encephalitis virus
TB
innate immunity of the mamary glands
Lactoferrin binds iron which then cannot be utilised by bacteria (bactericidal)
Macrophages are the most numerous cell types in normal milk
Neutrophil numbers are low unless bacterial infection- Can increase to be the dominant cell type in less than two hours
Neutrophils struggle to function in milk
Unknown fully why- Can’t swim and phagocytose at the same time? Coated by casein?
Are also defective before crossing into the milk from blood in late pregnancy/early parturition- Stress/hormones/nutrition?
adaptive immunity of the mamary glands
Colostrum contains abundant immunoglobulins
Protective and transfer of immunity
Immunoglobulins also present in milk but less- primary is IgG
Mastitis
Different forms of infectious mastitis occur according to:
the aetiology
the host response
These factors determine the severity of the clinical signs and pathophysiology
Severity of mastitis can range from:
increased cell counts with no macroscopic changes
progressive fibrosis
severe toxaemia
Diagnosis of the bacteria is important-
Obligate mammary pathogen?
Staph aureus (most common)
Streptococcus agalactiae
Mycoplasma sp
Environmental?
E.coli
Both
Strep.uberis and dysgalactiae
mastitis in cattle presenting as Severe necrotizing/gangrenous
Gram –ve bacteria
Endotoxin production ->Massive cytokine release -> necrosis -> increase in vascular perm
Wet gangrene
Quarter may slough
Sick cow
mastitis in cattle presenting as Suppurative
Gram +ve bacteria-
Trueperella pyogenes
Strep.dysgalactiae
Mycoplasma bovis
Dry cows (Summer mastitis)
mastitis in cattle presenting as Granulomatous
Contamination of teat-administered drugs are contaminated-
Nocardia
Cryptococcus
Atypical Mycobacteria
Candida
can be distinguuished form tb as its lwer in the ducts
Viral mastitis in goats
Caprine arthritis and encephalitis (CAEV)-
Retrovirus
Indurative mastitis- Hard udder
Pathogenesis
Not fully understood.
Virus-infected macrophages in colostrum and milk are absorbed intact through the gastrointestinal mucosa.
Spread throughout the body via infected mononuclear cells.
Periodic viral replication and macrophage maturation induce massive lymphoproliferative lesions in target tissues and organs such as the lungs, synovium, choroid plexus, and udder.
Persists by residing as provirus within host cells
Fibroadenomatous hyperplasia
a rapid proliferation of mammary stroma and duct epithelium of 1 or more glands
a non-neoplastic, benign condition that is seen most often in young, intact female cats
Cats
Young intact females
Progesterone
neoplastic mammary tumours
Mammary cancers are common in the dog and cat
As a general rule
Dog = benign
Cat = malignant
What is an abortion? Cattle
the production of one or more calves between 50 and 270 days of gestation; with calves being born dead or surviving for less than 24 hours•All cases where the pregnancy terminates earlyand the foetus is expelled are called abortions. Abortion may be defined as the loss of a foetus between day 42 and 271 of pregnancy, with foetal loss before this stage defined as early embryonic death (before day 14) and late embryonic death (between days 14 and 42). UK law states:•“abortion or premature calving” means an abortion or calving which takes place less than 271 days after service or insemination, or 265 days after implantation or transfer of an embryo, whether the calf is born dead or alive.NB: Not all abortions result in the expulsion of the fetus(es)#
Why investigate?
•Statutory –Brucella abortus
•Economy £630 loss (2007)
•Zoonoses
•Herd health plan: prevention
•‘Sleep at night’
Aims of investigation are:
•To determine the cause
•To rule out infection(s)
Bovine abortion: when should you investigate?
Sporadic abortions are normal: unavoidable losses considered to be between 1.7-2.0%
•Ignore twinning?
•‘Action level’: increased abortion incidence >3%
•Several abortions in short time
•Depends on calving pattern
•Sick cows, other signs
•Feed change or following treatments
infectios causes of abortion in cattle
•Specific e.g. Brucella abortus•Non-specific e.g. Escherichia coli
miscelaneous causes of abortion of cattle
•Drug-induced (prostaglandin, corticosteroid)
•Insemination/intra-uterineinfusion
•Trauma/stress (transport, noise, veterinary treatment etc.)
•High fever andendotoxins(toxic plants, nitrate/nitrite, fungal toxins, other disease)
•Nutritional (malnutrition, vitamin A deficiency,selenium/vitamin E deficiency, goitre/hypothyroidism- more imortant for still births, wont abort till very end of pregnancy)
•Twin pregnancy
•Genetic (malformation)
Descriptive pathology in aborted cattle
Placenta-
•Chorioallantois not amnion
•Size and number of cotyledons (range 72-125)
•Freshness: smell, colour, texture
•Cotyledons: red, pale, necrotic, exudate; fibrin/pus
•Intercotyledonaryareas:thickened/’plaques’, exudate; fibrin/pus
Aborted calf-
•Freshness: smell, colour of viscera (all similar after 24-48hr death in utero)
•Size, weight, crown rump length, features of development
•Skin lesions, covered with exudate, meconium
•Excess fluid in body cavities: clear, pink, red, fibrin
•Stomach content:meconium- means calf has been stressed
Visceral lesions-
•Lungs –inflated (pink, spongey) or not (atelectic; dark pink/red)
•Liver –haemorrhages, multifocal lesions, abnormal size/shape/structures
•Intestine –atresia (colon, rectum, etc), inflammation/necrosis
•Kidney –number, structure
•Heart–size, shape, anatomy
•Musculoskeletal and others–‘describe what you see’
Brain-
•Size and structure, abnormalities?
•Cavitation of cerebral hemispheres: hydranencephaly, porencephaly
•Cerebellar hypoplasia
what samples would be taken from an cattle abortion
Aborted calf (if suitable)
•Placenta
•Maternal blood?
•Bulk milk?
•Cohort bloods?
•Faeces, environmental samples, etc?
Calf samples
•Fresh-
•Stomach content -Bacteriology, fungal examination(liver or lung if unavailable):
•Spleen or thymus-PCR pestivirus
•Kidney- PCR Leptospires
•Foetal fluid- PCR Leptospires(Antibody tests)
•Brain- PCR Neospora
•Thyroid (stillborn)- Weigh, iodine
adrenal or liver- PCR BoHV-1
Fixed-
•Lung, brain, liver, heart, + stomach wall, eyelid- Histopathology
Placental samples-
•Fixed and fresh cotyledon- Modified ZiehlNeelsen: Coxiella(q-fever),Chlamydia, (+PCR), fungal examination, histopathology
Brucellosis
Brucella abortus primarily in cattle
Brucella melitensis and Brucella suis infections are possible
Clinical signs:
Abortions usually 5 to 9 months gestation
Retained Foetal membranes and endometritis
Orchitis and epididymitis in bulls
Hygroma- fluid-filled swelling surrounded by a thick capsule of fibrous tissue that develops under the skin
UK history Last outbreak: Cornwall 2004Suckler herd
Zoonotic risk: Brucellaspecies are highly infectious to humans:➢raw milk➢infected animals and carcases/placentae
Asymptomatic infection in young animals and non pregnant femalesAcute infections: organism in most LNs
Even in absence of abortion profuse B. abortus discharge from placenta, fetal tissues/fluids and uterine/vaginal exudateMammary gland and LNs may be infected, excretion in milk
Chronic infection also occurs:➢usually do not abort➢excrete in milk and from uterus
sInfertility in male and female
Brucellosis: laboratory testing
•Brucella culture (Farrell’s) on all aborted and stillborn fetuses/placentae or samples-
•Milk, mammary gland, reproductive organs*- *if infection/disease suspected
•MZN examination: presumptive identification•Specific culture and PCR confirmation
Serology-
•RBPT- Rose Bengal plate test
•CFT-omplement fixation test
•ELISA
bacterial causes of abortions in cattle
zoonotic- SalmonellaDublinother Salmonellae: S. Typhimurium, S. Mbandaka, S. MontevideoListeria monocytogenes
Coxiella burnetiiChlamydia abortusLeptospirosis
nonzoonotic- Bacillus licheniformis
Fungi: Aspergillus fumigatus, Mucor, Absidia, etc
Trueperella pyogenes
Pasteurella, Mannheimia, HistophilussppCampylobacter species
SalmonellaDublin
Member of the Enterobacteriaceae
Gram negative bacillus, Modified ZiehlNeelson
(MZN) positive
Several manifestations of disease:
➢Abortion
➢Enteritis
➢Pneumonia
➢Septicaemia
➢Joint ill (polyarthritis)
➢Meningitis/encephalitis
➢Osteomyelitis- proximal thoratic vertebrae
➢Gangrene of extremities (feet, tail, ears)- calves
Also causes chronic infection (carriers)
Spread by movement of animals and faeces(PVS, farmers, etc)
Listeria monocytogenes,
Soil/environmental- gets into silage
Gram positive coccobacillus
Survives in reduced pH (to around pH 5.5)
Associated with ‘spoilt silage’: soil, poor anaerobiosis
Abortion, meningoencephalitis, septicaemia, eye infections
May see fine necrotic foci in the liver (‘miliaryhepatitis’)
Bacillus licheniformis
Gram positive spore-forming bacillus
Silage associated including liquor
Gross placentitis- leathery change- no cotelydons visible
Fungi infection in cattle: especially Aspergillus fumigatus
Silage and another feeds contaminant
Gross placentitis+fetal dermatitis- ring worm
Campylobacters
Campylobacter fetus venerealis
Campylobacter fetus venerealis intermedius-
Venereal disease
Carried asymptomatically by bull or cows
Infertility, EED, abortions
Control by stopping natural service (+vaccination)
Campylobacter fetus fetus-
Opportunistic sporadic abortions
Campylobacter jenuni, Campylobacter coli
Coxiella burnetii
Gram negative, pleomorphic, obligate intracellular bacterium
Carried asymptomatically in some cattle, sheep, goat
sZoonotic: in humans causes ‘Q fever’
Modified ZiehlNeelsonstains (placenta preferably), PCR
Greatest risk to humans is ‘dust’ from bedding- dapen down bedding, dont spread on windy days
Leptospirosis in cattle
Leptospira hardjobovis
Carried asymptomatically in kidneys of cows
Passed in urine
Zoonotic
Abortion, EED, stillbirths, perinatal mortality, infertility
Milk drop syndrome ‘flabby bag’
viral causes of abortion in cattle
Foot and mouth disease virus
Bluetongue virus
Bovine viral diarrhoea virus
Bovine herpesvirus-1 (BoHV-1
)Schmallenberg virus
Neospora caninum
Tritrichomonas fetus
Sarcocystis species?
Anaplasma phagocytophila: ‘Tick borne fever’
Neospora caninum
found via PCR: brain stem
•Histopathology:
➢Brain
➢Heart
➢Liver
non suprative inflamation- necrosis
•Not all PCR positives abort
•Dam serology
•Cohort and sibling bleeds
what causes of abortion in cattle can be found via bacteriology
Recognised pathogens:
•S. Dublin
•L. monocytogenes
Opportunists:•pure culture
•histopathology
what causes of abortion in cattle can be found via estivirusPCR, BOHV-1 PCR, IHC
viruses
what causes of abortion in cattle can be found via Brain PCR, histopathology
Neospora
what causes of abortion in cattle can be found via Placenta PCR, histopathology
Intracellular bacteria (MZN+)
what causes of abortion in cattle can be found via Antibody detection (FF)
•BVDv •Neosporacaninum •L. hardjo
Ovine abortion
Diagnostic rate for infectious causes around 53%
•Sporadic abortions are unavoidable
•Consider investigating when:•abortion incidence >2%
•several abortions in short time
•sick ewes, other signs
•management changes
•treatments
all sheep abortions will be screened for brucella
infectous causes of abortion is sheep
zoonotic- chlamydia abortus
toxoplasma gondii
campylobacter
salmonella
listeria
•Yersiniaspp.•
Other bacteria in pure culture
•Pestivirus
•Schmallenberg
Pathological examinations of sheep abortion
•Placenta usually required for EAE examination/diagnosis
•Also placenta best for toxoplasmosis
•May see lesions in lambs –liver, lung, brain
Sample collectionTests-
•Placenta to include cotyledons-MZN stains, PCR (Coxiella), PCR Toxo
•Stomach content-Bacteriology
•Body fluid- Toxoantibody (if no placenta)
•Spleen/thymus-Pestivirus
Follow-up investigations
•Fixed viscera, brain, placenta
•Ewes
•Blood samples
non infectious causes of abrotion in sheep
•Poor nutrition/BCS
•Pregnancy toxaemia •Rough handling
•Transport
•Vaccination, foot trimming
•Dog worry
•Fluke
•Worms
•Other diseases
what account for 70 -80% of the diagnoses of sheep abortion per year
Chlamydia abortus (Enzootic abortion)- abortions in last 3 weeks of pregnancy
Toxoplasmosis- can effect at any time, blame for bad scanning
Campylobacter
Chlamydia abortus: Enzootic abortion
Bought-in carrier sheep
•Severe placental damage
•Late pregnancy abortions (last 3 weeks)
•Weak lambs at term
•Infection from previous season: abort the next
•Same season infection: IP 6 weeks
•Damage limitation: long acting tetracycline
Pathology-
•Inflamed cotyledons/ intercotyledonary
•Thick necrotic exudate
Testing-
•MZ Nonplacental smears
•or stomach content if no placenta
•Dam serology useful on flock basis
oxoplasma gondii: toxoplasmosis in sheep
•Cat is definitive host -oocysts (up to 100 million) in cat faeces, can contaminate grazing, hay, straw, cereals, concentrates, silage
•10 oocysts infectious dose
•Losses at all stages of pregnancy including EED, abortions, mummies, weak full-term lambs
Pathology-
•Inflamed cotyledons with multifocal necrotic foci → totally necrotic cotyledons- strabery apearence
•Little/no intercotyledonaryreaction
•Non specificfoetalpathology
•Fresh →mummies
Testing-
•PCR on cotyledon
•Antibody detection (IFAT) on body fluid (if no placenta)
•(Brainhistopathology)
Dam serology useful on flock basis
Campylobacteriosis
campylobacter fetus fetus
•Campylobacter coli/jejuni
•Intestinal carriage by sheep: passed in faeces, vaginal discharges (rapid spread)
•Also wild birds, rodents, cattle
•Risks: ground feeding, feeding roots, poor trough hygiene
•Mix sheep prior to pregnancy- non pregnant sheep get immunity
•Imported vaccine
Losses at all stages of pregnancy, including weak full-term lambs
Pathology-
•Lambs: non specific → multifocal hepatitis
•Placenta –pale/small necrotic cotyledons
Testing
•Bacteriology on stomach content
•or liver/lungifabsent
•NB It takes 4 daysfor initial bacterial ID
Bacteriology on stomach contentof aborted fetus (or liver/lung if absent) can diagnose what in sheep
Overnight culture usually
•Salmonellae
•Listeria spp.
•Pure culture for opportunistsSalmonellae: S. Montevideo, S. Typhimurium, S. Dublin, many othersListeriaspp.:L. monocytogenes, L. ivanovii
Maternal serology for sheep abortion : how useful?
Titres to EAE and T. gondiipeak soon after abortion and decline slowly
•ToxoLAT > 64 positive: > 512 high titre
•EAE ELISA less easy to interpret
•Titres may be present in subsequent season: likely boosted by re-exposure
•Negative titres do not rule out infection: problem with screening animals
•Vaccinal titres low and decline after 3-4 months
•Useful for animals with low scanning %
•Not useful in single animals
Others-
•Border disease
•Leptospira hardjo
•Coxiella burnetii
Abortions in goats
Infectious causes compare with those of sheep
Tests similar but
•There is no foetal antibody test for Toxoplasma gondiiso can only test placenta
•Serology comparable but ELISA not validated (use CFT)
•Large herd outbreaks of Q fever in Holland resulted in significant human disease in late 2000s
Abortion control
•Isolate aborting animals: minimum of 3 weeks, risk from discharges
•Remove and dispose of aborted material: highly infectious
•Tetracyclines for EAE are only damage limitation, ewes remain infected
•Zoonotic care: several abortifacients are infectious for people, particular risk for pregnant women
Dogs – herpes virus
cause of foetal loss
More commonly causes death of puppies <2weeks old.
Herpes virus is latent in the bitch causing no to minimal clinical signs but recrudesces during late pregnancy.
Some adults will have ocular and/or vaginal discharge.
Puppies are infected during birth.
Viraemia as virus spread via macrophages.
Incubation period 6-10 days.
Puppies are anorexic, hypothermic, vocal, disorientated. Fading puppies? Most if not all of litter will die.
Optimum temperature for replication of the virus is 34-36c, hence (partly) why neonates are worse affected, and active warming can improve prognosis.
Gross lesions include bilateral, multifocal, petechial and ecchymotic haemorrhages of the kidneys and liver.
Necrosis in kidneys, liver and lungs. Typical intranuclear viral inclusion bodies.
Virus, like a lot of herpesviruses, is endotheliotropic so most lesions are typically due to death of endothelial cells resulting in damage to blood vessels.
Herpes virus is not a core vaccine, but can be given to breeding bitches at request BEFORE and during pregnancy.
Dogs – Brucella canis
cause of foetal loss
Zoonotic
Transmitted primarily through mating to the bitch then to puppies in utero and milk.
Abortion mid pregnancy due to placentitis and endometritis, and aborted material source of infection. Female may continue to shed bacteria intermittently for weeks to months.
Aborted foetuses may have renal haemorrhages but bronchopneumonia most typical.
If mated again, subsequent pregnancies may reach full term but neonates may be weak or die.
In the male, it causes infertility and epididymitis.
Dogs with no clinical signs can still be infectious.
Discospondylitis common clinical presentation.
Testing methods include bacterial culture of any fluid from an adult/foetus and some practices are now offering serology for any imported animal prior to surgery.
Cats – feline panleukopenia virus
cause pof foetal loss
Parvovirus
Faeco-oral spread
Requires infection of rapidly dividing cells to replicate:
GIT
Bone marrow
Early in utero infection:
Foetal death and resorption
Perinatal infection-
2 wks prenatal - 2 wks postnatal
Infection of cerebellum at crucial developmental period- cerebellar hypoplasia -> ataxia
2-4 months postnatal-
Infection of bone marrow, thymus, GIT and mucosal lymphoid tissue
Leukopenia and enteritis
4-12months -
Enteritis
casuses of foetal loss in cats
feline panleukopenia virus
Feline alpha-herpes virus
Feline leukaemia virus
Feline infectious peritonitis virus
Coxiella burnetti
Salmonella spp
causes of foetal loss in dogs
herpes virus
Brucella canis
Salmonella spp.
Campylobacter jejuni
Strep. canis
Leptospirosis spp.
Toxosporosis gondii
Neospora caninum
Leishmania infantum
causes of equine abortion
Screen for contagious diseases to prevent spread
•Equid Herpesvirus-1 (EHV-1)
•Equine Arteritis Virus (EAV)
(Taylorellaequigenitalis(CEMO) –rarely causes abortion)
most causes sporadic
some cause abortion at specific gestational ages
evh1 needs to be rulled out
identified by pcr- takes only 1 day
external examination of aborted foal
•Measure crown-rump length (CRL)
•Weight
•Jaundice?
•Meconium staining?
•Haemorrhage?
•Congenital abnormalities
•Carcase condition
•Carcase preservation
samples for virology (pcr) in the aborted foal
thymus, lung, liver, spleen (kidney- in one container
4 small pieces of chorioallentois in another container
samples for bacteriology in the aborted foal
Liver(or heart blood if liver too soft)•Lung (or stomach content)•Chorioallantois
internal examination and samples for histology in the aborted foal
Examine internal organs and sample (our protocol):
•Liver–4 small samples ~1-2 cm cubed
•Lungs–4 small samples from different lobes
•Spleen
•Adrenal gland
•Kidney–wedge from centre of each kidney (cortex to pelvis)
•Thymus
•Conjunctiva
•Thyroid
•Heart
•Chorioallantois –5 sample
•Amnion –2 samples
•Umbilical cord –2 cm section
•Any abnormal findings should be sampled
examine gut for myconium
placental assesmet in the aborted foal
Amnion (allantoamnion)-
•Cut amnion away from umbilical cord and cut open to lay out flat
•Weigh
•Examine
•2 samples –over blood vessels
amniotic plauques- incidental
Umbilical cord-Measure length, circumference, weight
could see- cord compromise and torsion with haemorrhage and oedema of cord
Chorioallantois- Weigh, examine allantoic side and chorionic side.
allantoic vesicles- oedema
normal unruptured cervical scar
avillous area over blood vessels- incidental
Ascending placentitis (from the cervix) in the horse
•Predominantly bacterial•Fungal uncommon in UK
thickened leathery aperence of placenta
EHV abortion
Markedly increased clear yellow fluid, thorax and pericardium
•Jaundice
Thymic necrosis –
•colourchange from pink to cream-tan
•liquefaction
mutifocal hepatic necrosis
Jaundice
•Pulmonary consolidation
•Intranuclear inclusion bodies in hepatocytes
EHV-4-
▪Usually sporadic cases
▪Usually have excess of body fluids
▪Liver / lung lesions –sparse or absent
▪Spleen –best site for virus isolation
▪Many lesions secondary to hypoxia (alive foals may survive)
If jills (female ferret) are not mated or induced she can develop
a life-threatening pancytopenia.
clinical signs of Ovarian and uterine disease
in exotic mammals
Infertility
Abdominal distension
Weight loss
Poor body condition
Vaginal discharge
Non specific (anorexia, lethargy)
Pain (bruxism – pain scoring recommended)
Other signs, e.g., GI ileus/stasis
clinical signs of mammary disease
in exotic mammals
Development of masses
Swollen glands
Discharge
Pyrexia
Non specific
clinical signs of testicular disease
in exotic mammals
Change in testicular shape and texture
Change in libido
Inflammation/papules/ulcers
Common differential diagnoses/diseases for reproductive disease - female exotic mammals
Diseases not related to reproductive system-
Urinary tract disease
Normal urine pigmentation– porphyrin, food pigments
Ascites (for abdominal distension)
Ovarian disease-
Abscesses
Cysts
Neoplasia
Uterine disease-
Neoplasia- Uterine adenocarcinoma (rabbits)
Polyps
Infection
Pyometra, metritis, endometritis
Hydrometra
Endometrial hyperplasia
Torsion
Endometrial aneurysms
Vaginal and vulval disease-
Congenital
Neoplasia
Prolapse
Vulvitis-Treponema cuniculi
Other-
(Pregnancy)
Dystocia
Pseudopregnancy
Pregnancy toxaemia
Mammary gland disease-
Neoplasia
Mastitis
Common differential diagnoses/diseases for reproductive disease - male exotic mammals
Testicular neoplasia
Cryptorchidism
Orchitis
Epididymitis
Prostatic cysts (male neutered ferrets)
Preputial/testicular trauma (rabbits)
Treponema paraluis cuniculi.
diagnostics for repro disease in exotic mammals
Similar diagnostic testing methods used for dogs and cats.
Blood work to assess overall health.
Ferrets > oestrogen induced anaemia> collect from saphenous or cephalic vein.
Oestrogen induced anaemia >thrombocytopenia, leukopenia & anaemia.
Uterine infection > heterophilia with a slight leucocytosis
Radiography-
Abdominal and thoracic radiography
Thoracic > pulmonary metastases
Abdominal > mass associated with reproductive tract
Ultrasonography-
? Free abdominal fluid
Pregnancy
Solid mass, versus cysts or fluid filled uterus
Ultrasound guided FNA
Advanced imaging-
CT +/- contrast
Cytology
Culture and sensitivity
Histopathology
repro problems of female rabbits
Normal pregnancy – need to know normal-
Extrauterine pregnancy
Dystocia
Pseudopregnancy
Pregnancy toxaemia
Uterine disorders-
Pyometra- Purulent vaginal discharge
Lethargy
Inappetent
Enlarged uterus palpable, ultrasonography, cytology, haematology, serum biochemistry
Mucometra- Build up of mucus within uterine lumen
Hydrometra- Build up of transudate fluid in the uterus
Weight gain, but decline in body condition, anorexia, respiratory compromise, abdominal enlargement
Clinical signs, ultrasonography
Neoplasia-
Uterine adenocarcinoma
Most common tumour in female entire rabbits
Serosanguinous vaginal discharge or haematuria
Nonspecific signs > anorexia, depression
Dyspnoea if pulmonary metastasis
Diagnosis >palpation, radiography (chest as well), ultrasonography, histopathology
Often multicentric and involve both horns of the uterus
Metastasis via local spread into the peritoneum and other abdominal organs liver
Metastasis via haematogenous route lungs, brain, skin or bones
Cystic mammary glands may be seen in association with this
Mammary gland disease-
Mammary masses-
Progression from cystic mastitis
Development of irregular sized, fluctuant, subcutaneous nodules
Discharge – milk or amber fluid
Clinical signs, FNA and cytology
Mastitis-
Lactating or pseudopregnant does
Common isolates
Staphylococcus aureus
Pasteurella spp.
Streptococcus spp.
Hot, swollen, firm, painful glands
Pyrexia
Depression
Clinical signs, culture and sensitivity.
normal rabbit pregnancy
Gestation = 30-32 days
Often can gently palpate olive-sized masses from day 10
Fetuses can be seen on ultrasound from day 12
Fetuses difficult to feel abdominally from day 14
Parturition often day 30-32 – usually in the morning and quick
Fetuses will not survive after day 35
repro disease in the male rabbit
Testicular tumour-
Seminomas, interstitial cell tumours, Sertoli cell tumours, lymphoma
Non-painful, firm, nodular testicular enlargement
Cryptorchidism-
Normally descend by 12 weeks
Scrotal sac does not develop on the side of the cryptorchid testicle
Orchitis and epididymitis
Bacteria > Pasteurella multocida
Viral > Myxomatosis
Trauma
Swollen testes/scrotum, depression, anorexia
Trauma-Bite wounds, testicular evisceration and secondary infection
Venereal spirochetosis-
Treponema paraluis cuniculi
Redness, oedema, vesicles, ulcers, scabs around perineum and genitalia (+ face)
Clinical signs, microscopic visualisation, silver stains on biopsy, serological testing
Oestrus cycle - ferrets
Seasonally polyoestrus.
Jills remain in oestrus until they are mated, or chemically brought out of oestrus, or the day length shortens.
Pro-oestrus indicated by increase in vulva swelling. Oestrus follows – will see large, swollen vulva & behavioural changes.
Prolonged oestrus = increases risk of persistent hyperoestrogenism >development of pancytopenia due to bone marrow suppression.
Induced/reflex ovulators- Mating a rough process
Gestation 42 days
Litter size 6-8
Persistent oestrus > pancytopenia
Subcutaneous and mucosal petechiae
Ecchymoses
Swollen vulva
Pale mucous membranes
Abdominal distension
Blood from cephalic vein
Poor prognosis
repeo disease of ferrits
Persistent oestrus > pancytopenia-
Subcutaneous and mucosal petechiae
Ecchymoses
Swollen vulva
Pale mucous membranes
Abdominal distension
Blood from cephalic vein
Poor prognosis
Pyometra > ascending infection
Poor hygiene/husbandry
Aggressive hob behaviour
Mastitis-
After whelping or after third week of feeding
Inguinal glands commonly affected first
Susceptible to pseudopregnancy > implantation failure due to effects of photoperiod or lack of conception.
Associated with HCG injection or mated with a vasectomised hob
CS – weight gain, mammary enlargement & nesting behaviour.
Pseudopregnant jills may develop a fuller hair coat.
After the ‘whelping’ date > jill will cycle back to normal
adrenal disease-Correlation with surgical neutering
Increase in concentrations of gonadotrophins loss of negative feedback > stimulation of adrenal cortex >adrenocortical hyperplasia and tumour formation
CS > symmetrical alopecia, ‘rat tail’, pruritis
Vulva swelling
Recurrence of sexual behaviour
Urinary incontinence > prostatic enlargement
repro disease of gerbils
High incidence of ovarian disease-
Ovarian cysts
Neoplasia
Clinical signs: abdominal distension, bilateral alopecia, weight loss, decrease appetite, respiratory effort.
Diagnosis: clinical signs, imaging
repro disease of hamster
Pyometra (hamsters & gerbils)
Care not to misinterpret in hamsters
Diagnosis: clinical signs, ultrasonography, cytology
reprodisease of rats and mice
Neoplasia (mammary tumours)
Rats - subcutaneous fibroadenoma
Oestrogen and prolactin are thought to playa role in tumour development.
? Early neutering as a preventative measure
repro disease of chinchillas
Primary reproductive disease is rare.
In males, fur ring occurs around the base of the penis
Can cause paraphimosis and balanoposthitis (inflammation of the prepuce and glans penis)
Clinical signs = excessive grooming of the area, lethargy, straining to urinate.
repro disease of hedgehogs
Clinical signs > haemorrhagic vaginal discharge or haematuria
Differentials
Uterine neoplasia-
Adenosarcoma
Endometrial stromal sarcoma
Adenoleiomyosarcoma
Spindle cell tumour
Adenoleiomyoma
Endometrial polyps
Endometrial venous aneurysms
Diagnosis-
Clinical exam (abdominal mass)
Radiography
how haematoxylin and eosin staining is performed and why
A common laboratory method that uses two dyes called hematoxylin and eosin that make it easier to see different parts of the cell under a microscope. Hematoxylin shows the ribosomes, chromatin (genetic material) within the nucleus, and other structures as a deep blue-purple color. Eosin shows the cytoplasm, collagen, connective tissue, and other structures that surround and support the cell as an orange-pink-red color. H and E staining helps identify different types of cells and tissues and provides important information about the pattern, shape, and structure of cells in a tissue sample.
congenital inclusion cysts
similar to development of cysts in female-
incidental finsings
segmental aplasia of mesonephric duct
most commonly manifested as an absence of parts of the epididymis
Hypospadia
Anomalous/congenital condition
failure of the urogenital groove to close in the male
birth defect in boys in which the opening of the urethra is not located at the tip of the penis.
neoplasms of the testicle
Interstitial/Leydig cell tumour
Seminoma
Sertoli cell tumour
neoplasms of the scrotum
Vascular hamartoma, haemangioma and haemangiosarcoma
Melanoma
Mast cell tumour
neoplasm of the testicle- Sertoli cell tumours
Grossly:
The tumours are white
Irregularly ovoid
Lobulated
Bulge when cut
May be cystic
Abundant fibrous stroma makes then firm to hard
May cause marked distortion of the testicle
Most are benign
The incidence of Sertoli cell tumours is 20 times higher in cryptorchid dogs
Up to 30% of affected dogs produce excessive oestrogen, resulting in:
Feminization, including attraction of male dogs
Reduced libido
Testicular and penile atrophy
Preputial swelling
Perineal hernia
Gynecomastia
Redistribution of fat
Symmetrical, often ventral, alopecia.
Squamous metaplasia of the prostate gland (see later slide)
Oestrogenic depression of bone marrow can result in;
Anaemia
Thrombocytopenia
Granulocytopenia
Immunity in the male repro tract
The deferent duct is long and seminal fluid is constantly being produced, effectively flushing the tubular genitalia and hindering ascending infection.
Seminal fluid contains various antimicrobial products:
Chlorine
Blood-testis barrier-
Barrier between testicular interstitium and germ cells
Formed by intercellular junctions of Sertolli cells
Innate and acquired immune function is actively suppressed in testicular parenchyma, as spermatocytes, spermatids, and spermatozoa are highly antigenic and outside the blood-testis barrier
Innate and acquired immune function is actively suppressed in testicular parenchyma, as spermatocytes, spermatids, and spermatozoa are highly antigenic and outside the blood-testis barrier-
Any defect, injury or infection, that results in leakage of spermatozoa or spermatozoal antigens into the extra tubular compartment incites a foreign body or granulomatous response, fibrosis, continued disruption of tubules, sperm
Orchitis and epididymitis
Sheep-
Brucella ovis
Orchitis: Sheep/Goat pox virus, Visna/maedi virus, Trueperella pyogenes, Corynebacterium pseudotuberculosis, Brucella melitensis, Histophilus ovis
Epididmytis: Actinobacillus seminis (most important); Histophilus somni, Mannheimia haemolytica, E.coli, Trueperella pyogenes
Pigs-
Brucella suis
Cattle
Brucella abortus
Orchitis: Mycobacterium bovis, M. tuberculosis, E. coli, Proteus vulgaris, Corynebacterium ovis, Streptococcus , Staphylococcus sp., Trueperella pyogenes, Actinobacillus spp, Nocardia farcinica, Chlamydia spp,, and Mycoplasma sp
Epididymitis: bovine herpesvirus 4 (cytomegalovirus), Actinobacillus seminis, Mycoplasma bovigenitalium, Trypanosoma brucei
Dogs
Brucella canis- imported dogs
Cats
Naturally resistant to Brucella
Orchitis: FIP
Epididymitis is rare
Brucella is NECROTIZING
Chorioptes bovis
scrotal mange in SHEEP
Scrotal inflammation- can reduce fertility
Diseases of the prostate - prostatitis
Typically ascending
E.coli common
Abscessation and sepsis
Diseases of the prostate – benign hyperplasia
Benign prostatic hyperplasia is the most common disorder of the prostate in intact males
Under the influence of testosterone the prostate will become hyperplastic
Is symmetrical
May not cause issue but is palpable on rectal exam
Clinical signs include haematuria and preputial discharge
May be cystic
Resolves post castration
Diseases of the prostate – metaplasia
Metaplasia is the change from one differentiated cell type to another of the same germ layer.
In this case is from cuboidal epithelium in gland formation to stratified squamous
In the normal animal the change from specialised epithelia to strat. squamous is protective
In the case of prostatic squamous metaplasia, it is due to excess oestrogen via unknown pathogenesis
The excess oestrogen in this case would be from a Sertoli cell tumour
Diseases of the prostate – neoplasia
Carcinoma as epithelial and typically malignant
In the dog, arise more commonly from the urothelial tissue in the urethra= urothelial cell carcinoma (transitional cell carcinoma)-
Less commonly arise from the glandular parenchyma= prostatic adenocarcinoma - more common in humans and a mouse model
Posthitis
inflammation of the prepuce
Balanoposthitis
inflammation of the glans penis
Phalitis
inflammation of the entire penis
Phalophosthitis
inflammation of both penis and prepuce
Pizzle rot
Posthitis in sheep
Corynebacterium renale
Phaloposthitis in the bull
Bovine herpes virus 1
Phaloposthitis in the bull
Infectious pustular vulvovaginitis and abortion in the cow (see dry lab)
Respiratory disease in the calf
Papillomas
neoplasm of the penis and prepuce
Genital papillomas, or warts, on the penis seen in horses and cattle
Viral cause
In horses can progress to squamous cell carcinoma
Melanoma of the penis and prepuce
seen in grey horses
neoplasm
Name two viral causes of abortion in horses
Equine rhinopneumonitis is caused by equine herpesvirus 1 (EHV-1) and less often by EHV-4, and is the most important viral cause of abortion in horses. Abortion usually occurs after 7 months of pregnancy and there is no corresponding maternal illness. the disease is diagnosed by a blood test or isolation of the virus from fetal tissues. Prevention is based on vaccinating at 5, 7, and 9 months of pregnancy as well as preventing exposure of pregnant mares to horses that attend shows or other equine events where they may have been exposed to the disease. fetus may showe fetus showing dark red patches on fetal membrane
Equine viral arteritis may also cause abortion in horses 6 to 29 days after signs of infection appear. Signs of the disease include fever, swelling of the limbs, poor appetite, nasal discharge, and swelling of mammary glands. Stallions can be infected with the virus and carry the disease. Equine viral arteritis can be spread by sexual intercourse, artificial insemination with infected semen, or through the air. Infected horses usually recover without treatment. Prevention is based on vaccinating both the mare and the stallion.
Karyolysis
the complete dissolution of nuclear components of a dying cell
Karyorrhexis
the destructive fragmentation of the nucleus of a dying cell whereby its chromatin is distributed irregularly throughout the cytoplasm.
pyknosis
involves the shrinkage or condensation of a cell with increased nuclear compactness or density;
karyorrhexis refers to subsequent nuclear fragmentation (Fig. 5-29, F). Pyknosis and karyorrhexis are degenerative changes that are often observed in nonseptic exudates.
a. SMEDI in pigs
stillbirth, mummification, embryonic death, and infertility
often parvo
destroys fetus and neonates
mumification with progressive size difference
spread by oral or venereal rout
30 days- fetal death and reabsorbtion
30-70 days- mumification
after 7-0 days- noenatal death or healthy immune neonates
Inclusion bodies
uclear or cytoplasmic aggregates which are stainable substances, usually proteins, and formed due to viral multiplication or genetic disorders in human beings these bodies are either intracellular or extracellular abnormalities and they are specific to certain diseases.
describe the pathway of t4 and t3
hypothalamus produces TRH
pituitary produces TSH
thyroid produces t4 and t3
desribe the pathway of cortisol
stress prompts th hypothlamus to produce CRH
CRH prompts the pituitary to produce ACTH
ACT prompts the adrenal cortex to produce cortisol-
problems with assesing hormones
Dynamic systems: constant fluctuations in secretion and feedback allow maintenance of homeostasis
Present in low quantities
Variably stable/available to measure
IGF-1 measured as proxy for GH in cats with acromegaly
Can have significant diurnal variation
“Normal” can vary significantly between species, age, time of day, time of year
Variations post-treatment
how is the endocrine system measured?
Most common test type is sandwich ELISA
Dynamic versus basal/static measurements
Basal/static-
Concentration of hormone at that particular time point
E.g. Total T4, free T4, TSH
Dynamic-
Suppression testing:
drug/synthetic hormone administered which should result in negative feedback, suppressing hormone production
E.g. LDDST, HDDST
Stimulation testing:
synthetic stimulating hormone administered which should result in an exaggerated response of gland (hyperplastic/neoplastic)
E.g. ACTH stimulation
tests for Feline hyperthyroidism
Due to hyperplastic or neoplastic hyperthyroid gland- Over production of T3 and T4
Screening tests may show increased ALT
Basal testing of T4
Total T4 concentration (TT4)
highly specific for hyperT4
Easy and cheap, now available in house
BUT, 10% hyperT cats have T4 within reference range
Free T4 concentration (FT4)
More accurate reflection of thyroid status
Less readily available, more expensive, subject to sample handling errors
Beware the sick euthyroid- can have normal t4
how do you test for Canine hypothyroidism
Quite possibly the most over diagnosed endocrine disease in dogs
Age-related weight and behaviour changes
Overlap with HAC and other diseases
Serum concentrations of T4 decrease in older dogs naturally
Basal tests-
Total Thyroxine (T4) concentration
Free Thyroxine (T4) concentration
TSH concentration
TGAA antibodies
Expected results:
Euthyroid dog:
TT4 and FT4 within reference ranges
Sensitive
HypoT4:
TT4 and FT4 low
TSH increased
Thyroglobulin antibodies negative or positive
Dynamic testing:
TSH stimulation
Considered gold standard – but limited availability and expense of TSH
how do you test for Canine hyperadrenocorticism
Do no harm
Another overdiagnosed and potentially overtreated disease
No single test for Cushing’s has both high sensitivity and high specificity – all are a compromise between the two
Must have a strong clinical suspicion before performing testing
PU/PD +/- PP
Coat changes – alopecia, comedones (blackheads), thin skin
Abdominal distension (‘pot belly’) – due to enlarged liver and weak muscles
Lethargy, excessive panting, weakness
Weight gain
Prior tests:
Haematology: Stress leukogram- execss cortisol
Chemistry: increased ALP activity, hypercholesterolaemia
Urinalysis:
SG 1.001-1.030, proteinuria
Urine cortisol:creatinine ratio (UCCR)
Single test
Creatinine accounts for changes in urine concentration
Poor specificity (20%), high sensitivity (97%)
Negative: HAC unlikely
Dynamic tests-
ACTH stimulation test
Low-dose dexamethasone suppression test
High-dose dexamethasone suppression test
ACTH stim test
Relies on the fact that in natural HAC, the adrenal cortex is either hyperplastic or neoplastic so increased in volume so capable of making more cortisol than normal
High specificity (90%), moderate sensitivity (85% PDH and 50% ADH)
Normal: Increased cortisol to expected level
HAC: Increased cortisol beyond expected range (exaggerated response)
False positives:
Sick dogs with non-adrenal illness
False negatives
Certain drugs e.g. corticosteroids, progesterones, ketoconazole (+/- phenobarbital)
Test of choice for iatrogenic HAC
Chronic high doses corticosteroid (exogenous) results in adrenal gland atrophy and gland cannot respond to ACTH stimulation
Low dose dexamethasone suppression test
Relies on negative feedback to the pituitary gland so that in a normal animal, administration of a steroid will supress ACTH production and thus production of endogenous cortisol
If an animal has a productive pituitary tumour (PDH) or adrenal tumour (ADH) the adrenal glands will ignore this negative feedback and produce cortisol regardless
Moderate specificity (70%), high sensitivity (95%).
Interpretation:
Firstly, the presence or absence of Cushing’s syndrome is determined by examining the 8 hour result.
An 8 hour cortisol value greater than 40 nmol/l is generally considered to represent a ‘positive’ result
Typically in a dog with ADH, the adrenal tumour secretes cortisol autonomously and ACTH production is already suppressed, thus cortisol production is not suppressed in response to dexamethasone administration.
The second step only applies in the positive cases and checks for evidence of cortisol suppression.
In up to 60% of PDH cases, there will be marked suppression of cortisol (to <50% of the baseline value) at either 3 hours or 8 hours providing a way to differentiate between the two types of hypercortisolism.
High dose dex suppression test
What is Specified risk material ?
Cattle all ages – the tonsils, the last four metres of small intestine, the caecum, and the mesentery.
Over 12 months – skull excluding the mandible but including the brains and eyes, and spinal cord.
Over 30 months – vertebral column, excluding the vertebrae of the tail, the spinous and transverse processes of the cervical, thoracic and lumbar vertebrae, the median sacral crest and the wings of the sacrum, but including the dorsal root ganglia.
Sheep and goats All ages – the spleen and the ileum.
Over 12 months (or have a permanent incisor erupted) – skull including the brains and eyes, tonsils, spinal cord.
Dangerous Dogs act 2014
It is now against the law to let a dog be dangerously out of control anywhere.
The law was changed so that people could be prosecuted if their dogs carried out an attack anywhere, including in the owner’s own home.
The maximum prison sentence is
14 years for a fatal (human) dog attack
5 years for injury
3 years for an attack on an assistance dog
Finn’s law’ 2019 protects service animals
Prevents those who attack or injure service animals from claiming self defence
Finn is a police dog who was stabbed whilst pursuing a suspect with his handler. Finn sustained serious stab wounds to the chest and head, but only criminal damage charges could be brought against his attacker
‘Lucy’s Law’ protects puppies and kittens
This will mean that puppies and kittens can no longer be sold by a third party seller such as a pet shop or commercial dealer, unless they have bred the animal themselves. Instead, anyone looking to buy or adopt a puppy or kitten under six months must either deal directly with the breeder or an animal rehoming centre.
The law is named after Lucy, a Cavalier King Charles Spaniel who died in 2016 after being subjected to terrible conditions on a Welsh puppy farm
Chain of evidence
a legal concept
It requires that the origin and history of any exhibit presented as evidence must be clearly demonstrated to have followed an unbroken chain from its source to the court.
All persons handling the sample and the places and conditions of storage must be documented.
This includes a note of the time, date, place and signatures where appropriate.
This must include all specimen handovers and all key stages of processing.
serous atrophy of fat
a marrow disorder characterized by atrophy of hematopoietic and fat cells in the bone marrow with accumulation of gelatinous material.
indicates extreme starvation
signs of emaciation
blood clot in left ventricle- no rigor mortis
serous atrophy of fat
no fat in abdomen, heart, kidneys a dn marrow
no stromach in food indicates starvation
food in stmach with emaciation indicates disease
chelitis
inflamation of the lip
stomatitis
inflamation of the mouth
What can go wrong in the GIT- vascular?
mesenteric vessels
mesenteric arteries
attach toi mesenteric border so insissions shoud be made in the anti-mesenteric border
an infarction of one of these vessels will cause a wedge shaped, well demarcated, necrotic lesion- could be due to stronguus vulgaris in horse
volvulus- twisted gut. cause dilation on oral side, necrosis of twisted segment- segmentally necrotic
infection in the GIT
The gastrointestinal microbiome is very complex
Colonisation by an obligate pathogen (not usually found in gut) or overgrowth of a commensal (found in gut, normally not harmfull)?
The pathogenesis of the infectious agent will affect appearance but generally intestines, at least acutely, for most will be:
Hyperaemia- will look red, purposful build up of fluid for inflamatiion as opposed to congestion
Fluid filled lumen- damage to enterocytes (lumen of digestive tract) upsets balence and causes fluid build up
can be investigated by fecal culture- difficult with commensial microbes as they should always be there
Enterotoxaemia
Enterotoxaemia
bacterial toxins absorbed into bloodstream from intestines
Typically in veterinary species we are referring to various types of Clostridium perfringens:
Types A to E
All produce a different of combination of toxins
Type D produces epsilon toxin: Typically seen in fat weaned lambs after sudden diet change/increase in grain = overeating disease. certain bacteria adapted for certian food sorce so increase in grqin feeeds these colonies
Pore forming-
-Enterocyte necrosis: Necrohaemorrhagic
enteritis- sloughing of lining
-Kidney tubular cell necrosis- kidney autolyses fater than carcus “pulpy kidney”= glucosuria
-Increases vascular permeability:
Petechial haemorrhages
Pericardial effusion- clear to fibrinous fluid
Brain oedema -> neurological signs- Blindness, headpressing, ataxia
viral infection of the GIT
Most viruses generally prefer to infect cells with rapid turnover as can use their replicative mechanisms to produce more virus
GIT has constant cell turnover
Some viruses take this one step further and stimulate prolific growth
e.g. papilloma viruses
-Stimulate the cell cycle
In some cases inhibit innate cell-mediated immunity
Hyperplastic lesions -> papilloma (and sarcoids), often regress on their own but can get secondary infections
Malignant transformation in some cases-Squamous cell carcinoma, Cervical carcinoma in humans
sarciods in horse caused by papilloma virus from cows
Due to purpose of the GIT, viral shedding and therefore infectivity is high:
Faeco-oral transmission
Saliva- rabies ect
Many viruses of significant veterinary importance spend all if not most of their transmission cycle within the GIT
can cuase: erosion, ulceration, vesicles- foot and mouth, pustulates
Erosion
Ulceration
Loss of surface epithelium and extends into lamina propria/submucosa
Vesicle
Fluid filled space between layers of the epithelium
Blister
Also common in auto-immune diseases
foot and mouth
a disease that causes blistering of the skin and the inside of the mouth, nose, throat, eyes, and genitals. The disease is rare in the United States. Pemphigus is an autoimmune disease in which the immune system mistakenly attacks cells in the top layer of the skin (epidermis) and the mucous membranes.
Pustule
As per vesicle but contains necrotic material/pus
trauma of the GIT
impation
foreign body
herniation- chewing open of spay wound
congenital issues of the GIT tract
megaesophagus ect
Ileus
arrest of intestinal motility in the absence of an obstruction
Clinical signs-
Colic
Distension
Reflux/regurgitation- more common in horses
Vomiting- carnicores
Neuropathic-
Myasthenia gravis-
Clostridium botulinum -> Grass sickness. the toxin kills off neurons. causes impaction of colon and dry faecal balls. build up of fluid in proximal GIT
Inflammation-
Ileus common post surgery and stress- rabbits esspecially
metabolic issues of the GIT
Non GI causes of vomiting
Uraemia
Neurological
Addison’s-
Hypoadrenocorticism
Intermittent v+d+
Glucocorticoids maintain normal gastrointestinal mucosal integrity and function
Intestinal epithelial barrier disruption leads to permeability defects and the subsequent interaction of intestinal immune cells with the luminal contents. Activated immune cells release pro-inflammatory cytokines, such as TNF. In turn, TNF results in tight junction (TJ) disruption and intestinal epithelial cell (IEC) apoptosis and thereby exacerbates local inflammation. TNF also directly stimulates IECs to synthesize and release immunoregulatory glucocorticoids (GCs) to counter-balance excessive tissue damage. GCs act via the glucocorticoid receptor (GR) to inhibit TNF-mediated tissue damage in a negative feedback loop. The GR also inhibits pro-inflammatory transcription factors, including NF-κB, AP-1, and STATs leading to the resolution of the inflammation.
Neoplasia of the GIT
can be of endoderm- epithelium: squamus cell carcinoma in mouth, oesophagus, skin and stomach or squamus cell portion of stomach in horses
glangular epithelium- lining of gut, adenoma(benign), adenosarcoma(malignant)
git is immune organ- payers patches- lymphoma
can be of mesoderm- smooth muscle- layomyoma (benigns0, leyomyosarcoma (malignant)
serosa- plur- MESOTHELIUM- MESOTHELIOMAS
many autonomic nerves- uncommon to get neoplasms as they dont divide
endocrine tumours
FELINE CHRONIC GINGIVOSTOMATITIS (FCGS)
Presents as severe inflammation of the oral cavity
Most commonly affects the caudal oral mucosa:-palatoglossal arches (fauces),
-alveolar and buccal mucosa of the caudal oral cavity,
-less commonly soft palate and dorsal aspect of the caudal tongue-
The hard palate, labial mucosa and sublingual mucosa are usually spared
Not fully understood –probably several factors:
-Dental and periodontal disease,
-Altered immunological response,
-Infections: -feline calicivirus,
-FeLV, FIV, feline herpes virus-1,
-Pasteurella multocida, Bartonellaspp., Mycoplasma felis..
Usually affects adult cats
•Extremely painful
•Diminished food intake
•Weight loss
•Ptyalism
•Halitosis
•Unkempt appearance
histology for unclear clinical presentations for distinguishing between inflammation and squamous cell carcinoma (SCC)
histpathology-
Marked lymphoplasmacytic inflammation with prominent numbers of plasma cells
•Localised to the mucosa, but can extend into the submucosa (occasionally also sialadenitis, myositis)
•Mott cells = plasma cells with numerous globular cytoplasmic inclusions composed of immunoglobulin (Russell bodies)- grape like appearence
Hyperplasia and erosion of overlying epithelium
•Migration of neutrophils into the epithelium
•Variable numbers of macrophages, mast cells
treatment is to take out teeth- linked to poor teeth and therefore removal of presence of plauque may help
Eosinophilic granuloma complex (EGC)
Indolent Ulcer (Rodent ulcer, Eosinophilic Ulcer)
Eosinophilic plaque
Eosinophilic granuloma
Linear granuloma
group of lesions - skin, oral cavity and mucocutaneous junctions
histopathological findings = reaction pattern not specific disease
associated with hypersensitivities:
flea bite allergy**
food allergy
atopy
drug reactions
other potential causes or contributory factors:
bacterial infection
foreign body reactions
irritant reactions
self-trauma
endoparasites
genetic predisposition
In cats, it affects a broad age and breed range with common sites being: -dorsal surface of the tongue,
-palate,
-mucocutaneous junction of the rostral lips
In dogs, it is over-represented in Siberian huskies and Cavalier King Charles spaniels with common sites being:
-palate,
-less commonly tongue, lips, other mucosal sites
A complex of inflammatory diseases that represents a group of similar hypersensitivity reactions to various antigens (environmental, ingested materials, parasitic e.g fleas)
can be treated by treating these
Several clinical presentations/terms:
-linear granuloma
,-eosinophilic plaque/granuloma, -collagenolytic granuloma,
-indolent ulcer
histopathology-
Variable numbers of eosinophils (can be a mixed inflammatory population with eosinophils)
*↑ neutrophils in ulcerated areas
*Collagenolysis
*Cytology can often provide a diagnosis, so histology is not necessarily needed
The pathologist provides a diagnosis of eosinophilic or mixed inflammation (macrophages, lymphocytes) with eosinophils in more long term chronic cases-In highly indicative cases (based on histology and clinical history), the pathologist can mention EGC in the comment
OSTEOMYELITIS
infection of bone including the marrow
The source of infection can be:
-hematogenous(bacteraemia),
-implantation(open jaw fractures, contamination of surgical sites, bite wounds, gunshot wounds),
-local extension (from an infected tooth or periodontal tissues)
Common infectious agents are:
-Staphylococcusspp.,
-Streptococcusspp.,
-Truperellapyogenes,
-Nocardiaspp.,
-Coccidioides immitis,
-Cryptococcus neoformans
Osteomyelitis and destructive malignant neoplasms can have a similar appearance!
•Several things need to be taken into consideration:
-clinical examination,
-diagnostic imaging,
-histology,
-microbiology
Squamous cell carcinoma
*The most common non-odontogenicoral neoplasm in cats
*Can present as a proliferative, ulcerated lesion or a non-healing wound
*Often invades underlying bone
*Can metastasize, but usually later on
*Can mimic osteomyelitis on
X-ray
histopathology-
Keratin pearls = neoplastic keratinised squamous cells forming concentric layers
Neoplastic cells in SCC extend past the basement membrane into the underlying stromaThe majority of them is either well or moderately differentiated*Dysplastic changes of the epithelium may possibly evolve into SCC
The 2ndmost common non-odontogenicoral neoplasm in dogs
Risk factors: UV damage – white fur**
Pinnae, eyelids, nasal planum
Locally invasive and destructive
Variable appearance:
plaque-like, ulcerated, exophytic
nodules, scabby, red, inflamed…..
Temporal progression, can be slow
Uncommonly metastasize - local lymph node
if it occurs it is usually a late-stage feature
CANINECHRONICULCERATIVE(GINGIVO)STOMATITIS(CCUS)
Lesions most often occur on the buccal mucosa and lateral lingual mucosa opposite to larger tooth surfaces
Affected mucosa is often depigmented and mirrors the shape of the associated tooth → contact stomatitis
Predisposed breeds: greyhounds
•Poorly understood, most likely due to inflammatory reaction to persistent plaque bacterial biofilm that damages the mucosa
•Clinical signs:-drooling,-halitosis, -reluctance to eat
Histopathology-
•Lichenoid and perivascular infiltrate of B and T lymphocytes and plasma cells
•Often ulcerated epithelium, intercellular oedema, transmigration of neutrophils and T lymphocytes and sparse necrotic/apoptotic epithelial cells
•Granulation tissue formation beneath ulceration
MALIGNANT MELANOMA
The most common non-odontogenicoral neoplasm in dogs
•Mean age: 10.5 –12 years
•Early and high metastatic rate
•Often invades underlying bone (50%)
•Very rare in cats
•Melanocytoma, benign neoplasm of melanocytic origin, is very rare in the oral cavity
histopathology-
•Mitotic Index > 4/10 HPF
•↑ nuclear atypia
•Ki67 > 19.5 - proloferation measure
•↓ pigmentation
Amelanotic MALIGNANT MELANOMA-
Immunohistochemistry:-Melan A-PNL2(slightly ↑ sensitive than Melan A)
FIBROSARCOMA
The 3rdmost common non-odontogenicoral neoplasm in dogs
•Mean age: 8 years
•Maxillary and palatal lesions are more common than mandibular
•Locally aggressive, invasive and destructive
•Low metastatic rate
The 2ndmost common malignant oral neoplasm in cats (after SCC)
Histopathology-
Fibrosarcomaoramelanoticmalignantmelanoma?
FinaldiagnosiswithIHC:-vimentin+-MelanA –PNL2 -
Canine biologically high-grade/histologically low-grade FIBROSARCOMA (H/L FSA)
Most often arises from the maxillary gingiva•Most frequent in large breed dogs, especially Golden retrievers•Biologically very aggressive
histopathology-ery bland histology reminiscent of fibrous connective tissue•Histopathology cannot distinguish between H/L FSA and fibrous gingival hyperplasia or fibroma•Clinicopathological correlation is VITAL!
FIBROMATOUS EPULIS OF PERIODONTAL LIGAMENT ORIGIN (FEPLO)/PERIPHERAL ODONTOGENIC FIBROMA(POF)
•A common most likely reactive gingival lesion
•Mean age: 8.5 years
•Rostral maxilla is the most common site
•Locally invasive
•Very good prognosis even after marginal excision
histopathology-
•Three main components:-proliferative mesenchymal cells embedded in a collagenous stroma reminiscent of periodontal/gingival ligament,-cemento-osseous matrix,-odontogenic epithelium
CANINE ACANTHOMATOUSAMELOBLASTOMA (CAA)
•The most commonodontogenicneoplasm in dogs
•Mean age: 8.8 years
•Rostral mandible is the most common site
•Local invasion of underlying bone
•Does not metastasise
Histopathology-
Cardinal histologic features of odontogenic epithelium:-palisading of the basilar epithelium,-palisading epithelial cells have antibasilarnuclei,-palisading epithelial cells have a basilar clear zone within the cytoplasm,-odontogenic islands have central areas reminiscent of stellate reticulum (not present in CAA!)
•Can morphologically mimic SCC•No reliable IHC markers for odontogenic epithelium in veterinary medicine
Oesophagitis
Inflammation of the mucosa
Often due to acid reflux-
Weak sphincter?
Hernia - stomach herniates into oesopahgus– most common, especially in barachycepahlic breed
Oesophageal mucosal metaplasia- Strat squamus epithelium to columnar
Can be iatrogenic- Doxycycline in cats
Regurge during GA
May result in stricture
trauma of the oesophagus
stricture formation
Choke- food lodges in oesophagus
Persistent right aortic arch
disease of oesophagus
Vascular ring anomaly
German Shepherd dogs
Results in dilated oesophagus cranial to constriction
foetal vasculatue that should regress persists and forms tricture across oesophagus
Myasthenia gravis
anomolous/ ideopathic disease of oesophagus
Another important cause of megaoesophagus
Congenital and idiopathic forms- congenital form rare
Idiopathic due to antibodies against- acetylcholine receptor
This can be secondary tumours of the thymus
Aspiration pneumonia a risk
abomasitis
disease of abomasum
Bacterial-
Clostridium septicum- Braxy
Clostridium sordelli
Viral-
Rarely just the abomasum
BVD
Malignant catarrhal fever
Parasitic
gastritis
Gastritis as a single entity is rare in veterinary species
Inflammatory bowel disease
The stomach has a unique microbial flora due to the pH
Helicobacter spp are important in humans and ferrets (H. mustelae)- Associated with ulceration
Low numbers are consider unremarkable on gastric biopsies from dogs and cats
stomach ulcers
Primarily an issue in horses and pigs
Complicated and unclear pathogenesis-
Inappropriate feed
Stress
NSAIDs
Pigs-
Non-glandular oesophageal portion
Ruminal ulcers in cows typically associated with ruminal acidosis-
Caudal vena cava syndrome
Fungal overgrowth
Abomasal ulceration cause unclear
Traumatic reticuloperitonitis
Hardware disease
Wire or similar penetrates wall of reticulum
Pathophysiology varies from localised transmural inflammation of the wall of the reticulum to peritonitis to pericarditis
Clinical signs initially include -ruminoreticular atony
moderate ruminal tympany,
decrease in milk production
pyrexia
abdominal pain
-arched back, erect hairs at the withers, anxious expression, reluctance to move, and an uneasy, careful gait
pain going down hill
whithers/pole test
Chronically ill to sudden death from heart failure
Uraemic gastropathy
metabolic problem of the stomach
In renal failure, nitrogenous toxins build up in the blood- movement of calcium and interaction with digestive acid in the stomach results in deposition of calcium in stomach- Ulceration and mineralisation
neoplastic disease of the stomach
Stomach tumours are generally rare in veterinary species
Squamous cell carcinoma in horses ->
in glandular stomachs-
Adenocarcinoma ->
Leiomyoma/sarcoma
Gastrointestinal stromal tumours
Lymphoma
Carcinoids
abomasal displacement
Left or right displaced abomasum
High yielding dairy cows
Multifactorial-
Hypomotility -Hypocalcaemia,High concentrate diet
RDA more commonly seen within 1 month of calving
LDA more common than RDA
results in Metabolic alkalosis with hypochloremia and hypokalemia
bloat
Bloat is a clinical syndrome relating to the clinically appreciable distension of the abdomen due to distension of the stomach
Typically due to the inability of liquid or gas to exit the stomach
Gastric dilation and gastric dilation/dilatation and volvulus (GDV)- bloat with gas and also
twinst in stomach
Gastric dilation/distension can occur if gorge on kibble
In cows referred to as ruminal tympany
In the cow there are two forms;
Frothy (primary)
Gas (secondary)
Frothy
Typically due to consumption of legumes- Lower ruminal ph (normal is 6.5 to 7.5)
Blocks eructation
Acute and deadly
Gas-
Due to physical or physiological inability to eructate;Choke, Vagal indigestion (problem with vagal nerve so stomach isnt inervated proerly)
More chronic
Difficult to detect post mortem- Bloat line= loss of congestion in stomach and caudal trachea as stomach blocks blood flow
can measure rumen ph for frothy bloat
Gastric dilation and gastric dilation/dilatation and volvulus (GDV)
Gastric dilation/distension can occur if gorge on kibble
GDV is typically gaseous with some liquid and food
Pathogenesis incompletely understood
Volvulus occurs first?
The pylorus and duodenum first migrate ventrally and cranially.
A volvulus of >180° causes occlusion of the distal oesophagus.
Compress vasculature-
Caudal vena cava
Stomach and splenic -> necrosis
Fluid “lost” into the stomach-
Metabolic acidosis
Hypovolaemia shock- use lactate to determine prognosis
Severely ill, clinical emergency
DIC- dogs can go into disseminated intravascular coagulation sue to the stasis of blood due to twist and the endothelial damage
gastric dilation in horses
Gastric dilation as a primary disease rare in horses
Will quickly fill with fluid in cases of obstructive colic
Also will occur in motility disorders, Most well known would be grass sickness-
Clostridium botulinum
Autonomic neurones lost
No peristalsis
DIC
isseminated intravascular coagulation (DIC) is a rare but serious condition that causes abnormal blood clotting throughout the body’s blood vessels.
perforation of the stomach
Gaseous distension of the GIT is a common post mortem finding, especially farm animals
May perforate if left long enough
Did this perforation occur before or after death?
INFLAMMATION CANNOT OCCUR AFTER DEATH
Gross- Fibrin
Histo- No cellular response
causes of intestinal pathology
Displacements/obstructions- motility
Malabsorption(villus atrophy)- loss or damage to brush borders
Maldigestion- bile duct issues- osmotic dihorea
intestine wall efficient with absorbtion but this also allows infection into blood stream
Clinical signs of intestinal dysfunction
•Abdominal pain (colic in large animals)
•Vomiting
•Diarrhoea -acute -chronic ± weight loss/ascites
•Constipation
However: may present together or be part of a systemic condition
Abdominal pain (colic in large animals)
Acute or chronic
Displacements:
•Volvulus (twisting on mesenteric axis)- in caecum
•Torsion (twisting on long axis)- involves mesentary
•intersuseption- intestine telescopes on itself
•Obstruction-internal (e.g. foreign body, parasites, tumour, intussusception)-external (e.g. strangulating lipoma)
•Thin walled veins get compressed
•Venous congestion•Ischaemic infarction
•Necrosis
• decreased Gut barrier function (bacterial translocation/endotoxaemia)
•Obstruction proximal
•Perforation
•Acute fibrinous/suppurativeperitonitis
rupture
Obstruction: upper intestinal tract
Presentation generally acute and severe
no intestinal absorbion happening distaly
stomach cannot empty
Fluid and gas above obstruction
•vomiting
•metabolic alkalosis (loss of acid in vomitus)
•dehydration
•reduced renal flow and resultant uraemia
Obstruction in lower intestinal tract
•generally less acute than upper intestinal tract (increased fluid resorptionproximal to obstruction reduced vomiting)
•Pressure (fluid and gas) ➔-ulceration and infarction ±perforation-haemorrhage/peritonitis
•Eventual metabolic acidosis due to dehydration and catabolism of fat and muscle (producing ketoacids)
Pathogenesis of diarrhoea
Four basic mechanisms:
1. Altered structure / permeability (malabsorption)
2. Altered epithelial cell transport (secretory diarrhoea)
3. Osmotic effects (e.g. maldigestion)- no proper enzymatic digestion of certain components and large molecules draw water out
4. Altered motility
The above mechanisms can operate in the small intestine, large intestine or both
leads to:
Loss of water
Dehydration
Haemoconcentration
Hypovolaemic shock
Loss of ions (principally sodium, potassium and bicarbonate):
Metabolic acidosisHypokalaemia
aetiology of acut diarrhoea
Often involves infectious disease (esp. young animals)
Viruses (e.g. rotavirus, coronavirus and parvovirus)
Bacteria (e.g. Campylobacter, Salmonella, Clostridium spp.)
Endoparasites (e.g. cyathostomes)
Protozoa (e.g. cryptosporidiosis and coccidiosis)
Many more!!!
Remember zoonotic potential
Targeted injury
different infectiomn swill attack different parts of structures
e.g parvo attacks intestinal cryp cuasing massive damage where as ecoli target only the microvillus
target of parvovirus
lacks own equipment for replication
targets intestinal cells that are activly replicateing- crypt, payers patches, bone marrow in kittens
cuases massive damage as reduces capibility for repair
Clostridialcolitis: horse (‘colitis X’) effects in the intestine
produce exotoxins- diffuse damage as opposed to multifocal
Endoparasitism: cyathostominosisin horses effects in intestine
larvae are quiesent in muscosa
mass emergence in winter/ early spring
causes extreme and sevear multifocal damage
diohroa through malabsrbtion
Chronic diarrhoea ± weight loss aetiology
Chronic enterocolitis :•Lymphoplasmacytic
•Eosinophilic
•Granulomatous
Lymphangiectasia
Endoparasitism
Neoplasia
Grass sickness
inflammatory bowel disease
•Syndrome associated with persistent intestinal inflammation of unknown cause- idiopathic
•Subdivided according to predominant inflammatory cell: •lymphoplasmacytic enteritis, •eosinophilic enteritis
Protein-losing enteropathy
consiquence of persistant inflamation in intestine
(i)Increased permeability to plasma proteins -lost to intestinal lumen
(ii) Chronic inflammation -lymphatic blockage
Main protein lost is albumin. Loss exceeds liver synthesis ➔hypoalbuminaemia➔lower plasma osmotic pressure➔oedema and ascites(wasting + emaciation may also be present)
Protein-losing enteropathy
consiquence of persistant inflamation in intestine
(i)Increased permeability to plasma proteins -lost to intestinal lumen
(ii) Chronic inflammation -lymphatic blockage
Main protein lost is albumin. Loss exceeds liver synthesis ➔hypoalbuminaemia➔lower plasma osmotic pressure➔oedema and ascites (wasting + emaciation may also be present due to lack of absorbtion)
Primary intestinal lymphangiectasia (PIL) is also called Waldmann’s disease. It is a rare disorder that causes you to lose special proteins from your intestine. The intestine is connected to lymph vessels.
Villus atrophy
blunting/stunting/fusion
Ieffect ofntestinal lymphoma (cat)
can result in secondary protein-losing enteropathy
dissrups arcayecture and therefor absorbtion
Granulomatous enteritis
inflamitory cells cause thickening
jhones disease- diffuse thickening
necrosis
impeads nutrient absorbtion
protien loss
pipe stem diorhoea
histeopathology-
macrophages- form multinuclead giant cell becuase they cannto phagocytose mycobacterium
endoparasitism of the intestine
Functional problems may relate to:
1.Malabsorption (e.g. cyathostomiasis)
2.Obstruction (e.g. ascariasis)- caused by sheer number of worms
3.Vascular compromise (e.g. large strongyle disease)- necrososis, affect mesenteric vasculature and cause infarctions
Grass sickness
unknown agent- effects horses at pastur, possibly botulinum agent releasing toxins
Damage to neurones results in complete lack of peristalsis
•Nasogastric reflux and oesophageal ulceration
•Gastric dilation and rupture
histologicaly the neurons will be few and chromatolytic (pink)
actute- 48 hours
chronic- greater than a week
Weight loss
Muscle tremors
Rhinitis sicca
Dysphagia
Patchy sweating
Constipation
Large colon impaction
often fatal
agonal changes of the liver
Terminal hypostasis will result in a congested liver
Diffusely reddened and heavy liver that oozes
Barbiturates exacerbate this
Important to differentiate from chronic heart failure
agonal changes of the liver
Terminal hypostasis will result in a congested liver
Diffusely reddened and heavy liver that oozes
Barbiturates exacerbate this
Important to differentiate from chronic heart failure
post mortem changes in the liver
The liver is a very metabolically active organ
After death hepatocytes may lyse and release enzymes
= autolysis
Macroscopically
early autolysis may not be obvious
with time tissue becomes paler, soft, friable and may exude fluid
mucosal linings may slough off easily e.g. intestine
Microscopically
early autolysis cells will swell
cytoplasmic and nuclear detail are lost
cells lose their cohesion to each otherkkmmmm
no inflammatory response
Exacerbated by influx of post mortem overgrowth of bacteria
= putrefaction
Macroscopically
Carcass blown up
Gas bubbling
Psuedomelanosis
A blue-green to block post mortem discoloration due to bacterial breakdown of haemoglobin produces hydrogen sulphide.
Microscopically
Bacteria
typically rods in farm animals (Clostridia)
No inflammation
Incidental changes in the liver
The liver is a large organ so a significant proportion must be destroyed before clinically appreciable true failure
As with any epithelial organ, cysts are relatively common and may or may not be pathological
Hepatocellular adenomas will need to become very large or rupture before causing an issue
vascular pathologies of the liver
Due to the unique blood supply, type of endothelia and architecture of the liver, oedema does not occur
Congestion however is very common
Infarction is very rare in the liver and tends to occur at the tips
Centrilobular (zone 3) hepatocytes are the furthest away from oxygenated blood and are also metabolically the most active, therefore are sensitive to cardiogenic failure
Chronic passive congestion due to chronic heart failure will result in chronic low oxygen delivery to the centrilobular hepatocytes
Grossly this appears as a zonal pattern with congestion of the central veins and pallor of the centrilobular hepatocytes
The centrilobular hepatocytes are pale due to hydropic degeneration (cell swelling – reversible)
Chronically these centrilobular hepatocytes may undergo necrosis and may be replaced by fibrosis which grossly appears as a “nutmeg” liver
Chronic anaemia will also cause loss of centrilobular hepatocytes
Liver lobe torsion is generally rare in veterinary medicine, except in rabbits
Telangiectasia is benign distension of sinusoids by blood seen most frequently in the cow.
Blood flow may also be compromised secondarily to diaphragmatic hernias
Portosystemic shunts
Blood from the portal system bypasses the liver
Due to anomalous vessel(s)
Can be congenital (Yorkshire Terrier) or acquired (Spaniels due to chronic liver disease)
Extra-hepatic (small breed) or intra-hepatic (large breed)
Clinically
Stunted growth
Hepatic encephalopathy
Biochemistry: Elevated serum bile acids, hypoalbuminemia, hyperammonaemia, hypoglobulinaemia, hypoglycaemia, decreased BUN, hypocholesterolemia
Urinalysis: Ammonium biurate crystals in alkaline urine
Haematology: mild to moderate microcytic, normochromic, nonregenerative anaemia
Grossly the liver is atrophic as lacking growth stimuli
Portosystemic shunts
vascular pathology of liver
Blood from the portal system bypasses the liver
Due to anomalous vessel(s)
Can be congenital (Yorkshire Terrier) or acquired (Spaniels due to chronic liver disease)
Extra-hepatic (small breed) or intra-hepatic (large breed)
Clinically-
Stunted growth
Hepatic encephalopathy
Biochemistry: Elevated serum bile acids, hypoalbuminemia, hyperammonaemia, hypoglobulinaemia, hypoglycaemia, decreased BUN, hypocholesterolemia
Urinalysis: Ammonium biurate crystals in alkaline urine
Haematology: mild to moderate microcytic, normochromic, nonregenerative anaemia
Grossly the liver is atrophic as lacking growth stimuli
infectious pathologies of the liver
The liver can be exposed to infectious agents through three main routes
Haematogenous
Biliary (ascending)
Direct extension
Neonates also have a direct connection between umbilicus and liver
The liver receives 100% of the blood flow from the GIT
Defence
Kupffer cells
Resident macrophages
IgA secreted into bile
viral-
Herpes-
Typically affects foetus and neonates
Characteristic intranuclear viral inclusion bodies
Adenoviruses-
Canine infectious hepatitis
Chickens
bacterial-
Innumerable types of bacteria may infect the liver
Bacteria from the GIT
May initially be peri-portal
Tyzzer’s disease
Clostridium pilliforme
Foals and laboratory species (gerbils)
Abscessation common
Ruminal acidosis damages the rumen mucosa, resulting in translocation of Fusobacterium necrophorum into the portal circulation-> hepatic abcesses -> caudal vena cava syndrome
Haematogenous bacteria
Typically random necrosis- salmonella, Listeria, Clostridia, Yersinia
Mycobacteria – pyogranulomas, Ziehl-Neelsen
Leptospirosis
Campylobacter (aborted lambs)
Leptospirosis
Clinical signs associated with leptospirosis vary and depend on the serovar and the host.
In maintenance hosts, leptospirosis generally is characterized by a low serological response, relatively mild acute clinical signs, and a prolonged renal carrier state which may be associated with chronic renal disease.
In incidental hosts, leptospirosis can cause severe disease.
Dogs
Young > old
Serovars icterohemmorrhagiae and canicola were believed to be responsible for most clinical cases of canine leptospirosis and after a bivalent serovar-specific vaccine against canicola and icterohemmorrhagiae came into widespread use, the incidence of “classic” leptospirosis in dogs decreased.
Clinical signs: fever, inappetence, vomiting, abdominal pain, diarrhoea, PUPD.
Depending on strain and host response, pathogenesis can be primarily due to hepatic or renal dysfunction or a combination.
Whilst the renal consequences of lepto were covered in a previous lecture, the liver is another major organ damaged during leptospirosis.
The degree of icterus in canine disease usually corresponds to the severity of hepatic necrosis.
Cattle
The icterus and haemoglobinuria that develop in cattle with leptospirosis results from a specific haemolytic toxin produced by serovar pomona.
Chronic canine hepatitis-
Enigmatic disease of incompletely understood pathogenesis
Spaniels, Dobermans and Labradors all over-represented, therefore genetic factors implicated
May be secondary to chronic infection, such as lepto, or copper toxicosis (see later)
Clinically the animal will have raised liver enzymes
Grossly characterized by a small liver with nodules of hepatocyte regeneration and hyperplasia, separated by bands of fibrosis
Proxy for cirrhosis
Histopathology reveals periportal inflammation predominantly with portal areas bridged by fibrosis
Feline triaditis-
In dogs, the common bile duct joins the duodenum at the major duodenal papilla, separately from the pancreatic duct. An accessory pancreatic duct joins the duodenum at the minor papilla in most dogs though anatomic variation exists.
In cats, the common bile duct fuses with the pancreatic duct before entering the major papilla. Only 20% of cats are estimated to have an accessory pancreatic duct
The canine CBD is 3mm in diameter and the feline CBD is 4mm in diameter
Probably due to their unique anatomical features of cats, whenever the intestine is inflamed, so too will be the pancreas and/or biliary tree
Cats are typically impressively jaundice
Likely post-hepatic
Histopath reveals portal and peri-portal inflammation, indicative of ascending infection
The liver can be affected by helminths in two ways
Target organ
Trematodes
Cestodes
Visceral migrans
Nematodes
fungal- histoplasmosis
protozoal- toxoplasmosis
Chronic canine hepatitis
Enigmatic disease of incompletely understood pathogenesis
Spaniels, Dobermans and Labradors all over-represented, therefore genetic factors implicated
May be secondary to chronic infection, such as lepto, or copper toxicosis (see later)
Clinically the animal will have raised liver enzymes
Grossly characterized by a small liver with nodules of hepatocyte regeneration and hyperplasia, separated by bands of fibrosis
Proxy for cirrhosis
Histopathology reveals periportal inflammation predominantly with portal areas bridged by fibrosis
Feline triaditis
In dogs, the common bile duct joins the duodenum at the major duodenal papilla, separately from the pancreatic duct. An accessory pancreatic duct joins the duodenum at the minor papilla in most dogs though anatomic variation exists.
In cats, the common bile duct fuses with the pancreatic duct before entering the major papilla. Only 20% of cats are estimated to have an accessory pancreatic duct
The canine CBD is 3mm in diameter and the feline CBD is 4mm in diameter
Probably due to their unique anatomical features of cats, whenever the intestine is inflamed, so too will be the pancreas and/or biliary tree
Cats are typically impressively jaundice
Likely post-hepatic
Histopath reveals portal and peri-portal inflammation, indicative of ascending infection
Cholangitis
Pancreatitis
Inflammatory bowel disease
Fascioloides hepatica
Common liver fluke of ruminants
Indirect life cycle
Three syndromes
Acute fasciolosis, normally seen in sheep, is caused by large numbers of juvenile fluke migrating through the liver. These cause extensive haemorrhage and damage to the liver parenchyma. Animals are typically weak, and anaemic, often with palpably large livers, abdominal pain, ascites and sudden death is common.
Chronic fasciolosisoccurs in both sheep and cattle and occurs several months after moderate intake of infective cysts. Chronic disease is associated with adult fluke in the bile ducts. Anaemia, loss of appetite and gradual weight loss are common clinical signs. Infection also has an impact on fertility, growth rates and milk production.
Black disease (Clostridium novyi) in sheep and bacillary hemoglobinuria (C. hemolyticum) in cattle (and sheep). Migration of immature flukes through the hepatic parenchyma may result in the generation of necessary ischemic conditions for the proliferation of clostridial spores, already within the liver, to proliferate. Once activated the clostridial bacteria produce toxins, resulting in necrosis in the liver and death in sheep with black disease or intravascular haemolysis with associated anaemia and haemoglobinuria in cattle.
liver cestodes
Echinococcus granulosus parasitizes canids as the definitive host, and the intermediate host is a large domestic species, such as cattle, sheep and horses. Canids pass the proglottids in areas where these animals graze, and upon ingestion the embryos develop into hydatid cysts.The cysts are most commonly found in the liver and lungs, although other organs can be infected; they may never result in clinical disease, but can result in carcass condemnation at time of slaughter.
E. multilocularis has a predominantly canid-rodent life cycle and has a more fulminant disease process wherein the liver can become completely effaced by cysts.
toxic pathology of the liver
Because of its function and exposure to portal blood flow, the liver is a major organ affected by toxins.
Centrilobular hepatocytes are most commonly affected, as most toxins are not truly toxic until metabolised by cytochrome P450.
Few toxins are toxic without metabolism and will thus cause periportal necrosis.
An inexhaustive list of hepatotoxins include
Plants and similar
Blue-green algae
Ragwort (pyrrollizidine alkaloids)
Amanita mushrooms
Mycotoxins
Chemical/drug
Xylitol
Carprofen
Acetaminophen/paracetamol
Whilst copper is an essential cofactor of many cellular processes, it is also a toxicant at high enough levels resulting in free radical formation
Acute
death primarily in ruminants due to haemolytic crisis and acute liver necrosis
sheep fed cattle feed and/or deficient in molybdenum
Gross – icterus, multifocal pan-lobular hepatic necrosis and gunmetal blue kidneys
Chronic
Bedlington Terriers have a defect in a copper transport gene, may be other breeds too
All dogs with CCH should have copper levels tested
Copper levels in dog food too high?
Because of the liver’s capacity to repair, chronic low grade toxicosis will result in regenerative nodules and fibrosis (see CCH slide)
With ragwort toxicity, the alkylating toxins prevent cell division, resulting in characteristic megalocytes with huge nuclei
Generally the liver is a good tissue to collect fresh samples from for acute toxicology sampling, and also from chronic copper levels (see wet lab). Cf: fat for chronic toxicosis.
metabloic pathology of the liver
Fatty liver disease/ketosis/twin lamb disease/hepatic lipidosis/steatosis
Terms used for lipid deposition in the liver
Physiology of lipid metabolism - recap
Lipid is delivered to the hepatocyte from dietary sources or body fat stores in the form of free fatty acids (FFAs).
A small amount of FFAs are also synthesized in the hepatocyte itself from acetate.
Some of the FFAs are utilized for the synthesis of cholesterol and phospholipids, and some may be oxidized to ketone bodies (1).
Most of the intracellular FFAs are esterified to triglycerides (2).
Once triglycerides are produced, they must be complexed to a lipid acceptor protein (or apoprotein) prior to export from the cell (3) as lipoproteins.
This requires protein and energy
Triglycerides may accumulate if the balance between the synthesis of triglycerides and their utilization or mobilization is deranged. When intracellular triglycerides accumulate, a fatty liver results.
Whilst hypoxia and toxins such as aflatoxins that affect protein synthesis in the liver can cause this, one of the main times to see this is when an animal can no longer rely on glucose as an energy source and free fatty acids are thus mobilised from adipose tissue as an alternative energy source
This is an example of reversible injury
idiopathic liver pathology
Gall bladder mucocele
Border Terriers
Kesimer, Mehmet, et al. “Excess secretion of gel-forming mucins and associated innate defense proteins with defective mucin un-packaging underpin gallbladder mucocele formation in dogs.”
normal function of the liver
Glycolysis/Gluconeogensis
Fatty Acid metabolism
Bile Acid excretion
Excretion of bilirubin
Detoxification of blood
Elimination of ammonia
Production of plasma proteins
Albumin
Clotting factors
hepatic insuficency in horses
lethargy/inappetance
weight loss
colic
photosensitisation- dermatitis and sunburn. pigments desposited by the liver are photosensitising agents
encephalopathy- high amonia levels effect neurotransmitters- results in neuro signs: ataxia ect
diarrhoea
jaundice- slight jaundice can also be caused by not eating as horses do not have a gall bladder. ecpression of ligand that binds billuruben is linked to eating/grazing
oedema
coagulopathy
≥70% of liver function must be lost before insufficiency occurs
Therefore:
mild or no clinical signs do not rule out liver disease
signs of insufficiency indicate severe damage and poor prognosis
aim to investigate and treat early cases (subclinical?)
ALT is NOT a good indicator of liver function in horses and other herbavores
GLDH much more specific in horse
liver biopsy in horses
Serum liver enzymes indicate the presence of liver disease only
Functional assays (BAs) indicate presence of disease and give some indication as to severity
Neither will provide specific information on what is causing the liver disease
BIOPSY is essential for gaining information regarding aetiology
Guides treatment options
Provides more accurate prognosis
nutritional support in liver disease
Special diets are only required if the liver is failing
Liver disease (in the absence of failure) does not require special dietary management
The liver controls nutrient storage/supply
feeding “little and often” seems sensible
High dietary protein can exacerbate hepatic encephalopathy (neurologic signs relating to high blood ammonia)
however protein restriction causes muscle breakdown
advice to humans is to eat vegetarian protein!
No need for B vitamins (if eating OK) and iron is hepatotoxic!
Supplementation with vits A,D,E,K may be helpful
Volvulus
twisting on mesenteric axis)
Virulence
Virulence is the ability of a microbe to cause pathological effects
Some microbes are completely avirulent- Commensal bacteria of the gut
Some microbes are only virulent under the right circumstances
Clostridium difficile
A commensal of the GIT in rabbits
Antibacterial-induced dysbiosis will cause overgrowth and disease
Most diseases we discuss in veterinary medicine are caused by obligate pathogens
The disease cannot replicate or spread without causing disease
Ebola virus
Enveloped virus that takes its envelope from the host cell, killing it in the process
The bodily fluids produced by this mass necrosis and haemorrhage are the infectious source for the next person
Some microbes vary depending on strain
Example: Newcastle disease virus
Highly virulent/velogenic strains
cause acute infections with high mortality
Mesogenic/intermediately virulent strains
cause respiratory disease in young chickens and decreased egg production
Lentogenic/avirulent strains
cause mild respiratory infection or give no symptoms in poultry
Virulence factors
Any gene product of a microbe that enables infectivity, colonisation and/or spread
May facilitate:
Adherence (e.g. UPEC P-pilus)
Invasion (e.g. Salmonella T3SS)
Immune evasion (e.g. Trypanosome variant surface glycoproteins (VSG))
Immune suppression (e.g. Influenza NS1 protein)
Acquisition of nutrients (e.g. bacterial siderophores to acquire iron)
Adherence
The first step in infection is binding to a host cell
Bacteria have adhesins known as pilli and fimbrae- Uropathogenic Escherichia coli (UPEC)
Viruses have specific ligands for specific cell receptors
SARS-CoV-2 binds to ACE2
Haemagglutinin in HPAI
MALT
Microbes colonizing a mucosal surface then need to cross the mucosa
In the GIT this is typically done at the site of MALT-
Mucosal-associated lymphoid tissue
Only site in GIT not covered by mucous
This can be done in one of seven ways
M-cell trafficking – PCV2
Intercellular – Leptospirosis
Transcytosis – Erysipelas
Dendritic cell sampling – Sheeppox
Lymphocyte trafficking – Rhodococcus equi
Macrophage trafficking – Rhodococcus equi
Neuronal – Herpesviruses
transcytosis
Transcytosis is a normal cellular process
Endocytosis at one side of the cell (1), moving through the cell cytoplasm in a membrane covered vesicle (2), then exocytosis out the other side (4).
In the healthy animal is used to transport macromolecules from one side of a cell to the other
There are three main types of endocytosis
Microbes typically hijack the receptor-mediated type or can be phagocytosed then evade destruction
spreadinf of microbes throught the body
Microbes can spread throughout the body by two main methods
Passive/cell free within blood or lymphatics
Relatively rare – typically eukaryotes
Leukocyte trafficking
Most common
Leukocyte trafficking
Mediated by macrophages, lymphocytes and dendritic cells
Phagocytosis is a normal cellular process whereby the above cells (and neutrophils) engulf microbes and/or foreign material for intracellular for destruction
Mediated by macrophages, lymphocytes and dendritic cells
Phagocytosis is a normal cellular process whereby the above cells (and neutrophils) engulf microbes and/or foreign material for intracellular for destruction
Microbes can hijack this process, avoiding intracellular digestion in two main ways
Block fusion of the phagosome with lysosomes-
TB
Block actions of lysosomal enzymes-
Johne’s disease
stains for bacteria that do not stain well with Gram-stain
Ziehl-Neelsen - Mycobacteria
Silver stain - Leptospirosis
what bacteria form large colonies
Actinomyces
Yersinia
Bacterial pathogenicity
Bacterial pathogenicity (ability to cause disease) is controlled by virulence factors
Virulence factors of bacteria are typically glycolipids or glycoproteins encoded by genes
Variably enable
Motility – flagella
Adhesion – adhesins
Invasion – invasins
Phagocyte resistance – biofilms and capsules
Phagocyte destruction – toxins
Tissue destruction – enzymes
Inhibition of phagolysosomes – antioxidants
Nutrition – siderophores – iron accumulation
Some are expressed on the bacterial surface and can be used to type the bacteria
See E.coli slides in large intestine lecture and later
Biofilms
Some bacteria form a polysaccharide matrix that confers a protective extracellular environment
Staph aureus and UPEC
Resists antimicrobials
Capsules
Typically G-ve but some G+ve bacteria (and fungi) have capsules
Enables attachment and nutrition, and evades phagocytosis
Adhesion
Attachment occurs when membrane proteins called adhesins, bind to receptors on cell membranes.
Attachment can be a specific ligand-receptor interaction - a protein on the bacterium binds to a receptor on a host target cell.
LPS
Other bacteria utilize extensions of their cell membranes - fimbriae or pili to bind to cells.
Fimbriae and pili bind to receptors on microvilli of the glycocalyx or in the mucus layer of epithelial cells.
Fimbriae and pili may also inhibit phagocytosis.
LPS
stands for lipopolysaccharide
Major component of gram-negative bacteria wall
Referred to as O-antigen
Virulence factor
Stabilises membrane and resists chemical attack
Adhesion and internalisation
Brucella abortus
Cardoso, Patrícia Gomes, et al. “Brucella spp noncanonical LPS: structure, biosynthesis, and interaction with host immune system.
It is and endotoxin
Released when G-ve bacteria die
Stimulates practically all “arms” of the immune system AND coagulation
Exotoxins
Exotoxins are actively produced by living G+ve bacteria
Exotoxins work in four main ways
Direct cytolysis
Clostridium perfringens
Pore-forming
Staph aureus
Inhibition of protein synthesis
Corynebacterium
Inhibition of ion pumps
ETEC E coli
LPTA
toxin
released by dead G+ve bacteria
Endotoxins
such as LPS are released from dead G-ve bacteria
Enteric coliobacillosis (Escherichia coli)
Enterotoxigenic (ETEC)-
Virulence factors:
Attachment via fimbriae – F5 (K99), F41; F42, F165, F17, F18; F4 (K88), F6.
Heat-labile (LT) and heat- stable toxins (ST), acting locally to alter secretion/absorption of electrolytes and water.
Enteropathogenic (EPEC)-
Virulence factors:
Intimin - loosening of tight-junctions between enterocytes.
Enterohaemorrhagic (EHEC)
Virulence factors:
Cytotoxic Shiga-/Vero- toxin
Pathogenesis and pathophysiology:
Non-structural alterations in cell membrane electrolyte and fluid transport (ETEC)
Secretory diarrhoea
Villus atrophy (EPEC)
Coagulative necrosis (EHEC)
Haemorrhagic diarrhoea
Bacillus anthracis
Bacterium exists as resistant endospores in environment and as vegetative forms
Unknown mechanisms of adhesion, colonisation and infection
Virulence factors
Capsule: poly-D-glutamic acid (non-toxic) – prevents killing and digestion, antibody attachment and phagocytosis
Toxins: 3 exotoxins acting together to cause cell death
Protective antigen – creates a pore in cell membrane allowing entry of remaining toxins, oedema and lethal factor
Inside cells
protective antigen + oedema factor oedema toxin
protective antigen + lethal factor lethal toxin
Pathogenesis and pathophysiology:
Oedema toxin disrupts electrolyte/water transport systems resulting in oedema
Lethal toxin causes cytokine production which act to cause cell death especially of macrophages and capillary endothelial cells)
Atrophic rhinitis of pigs
Bordetella bronchiseptica and Pasteurella multocida
Bordetella phase
Virulence factor:
Dermonecrotic toxin (DNT)
Pasteurella phase
Virulence factor
Pasteurella multocida toxin (PMT)
Pathogenesis and pathophysiology:
DNT
Kills epithelial cells allowing access of PMT to submucosa
PMT
Increases osteoclasts and inhibits osteoblasts-> turbinate atrophy
Clostridia perfringens
C. perfringensis classified into 5 major types (A, B, C, D, and E), based on the production of 4 major lethal toxins:
Type A produces alpha toxin
Type B produces alpha toxin, beta toxin, and epsilon toxin
Type C produces alpha toxin and beta toxin
Type D produces alpha toxin andepsilon toxin
Type E produces alpha toxin and iota toxin
Alphatoxin (CPA):
phospholipase C
Gas gangrene, canine haemorrhagic diarrhoea, ferret gastroenteritis
Epsilontoxin (ETX):
Pore forming in enterocytes and endothelial cells
Pulpy kidney
Bacterial persistence within phagocytes
Mycobacterial species are the classic example of this method of pathogenicity and this is a key reason why mycobacterial infections result in multifocal chronic lesions
Depending on the species, Mycobacteria can resist phagocyte killing in both ways
Blocking fusion of phagosome with lysosome
Blocking actions of lysosomal enzymes
This inability to rid the bacteria results in the creation of pyogranulomas
Immunity to viruses
Immunity against viruses involves interferon
interferon-induced apoptosis of infected cells
Interferon blocking viral replications
Adherence and tropism in viruses
Viruses are often relatively specific for which cells they infect
This is referred to as tissue tropism
Mechanism is that viruses bind to cells via ligand-receptor interactions
Other example would be Listeria (bacteria) having tropism for the brain as uses catecholamines as a food source
Some viruses require a specific receptor and a co-receptor
SARS
Some viruses are pan-tropic in that they can infect many cells
Canine distemper virus
Cells that allow entry of viruses are called susceptible cells
Cells that allow replication are called permissive cells
Permissive cells are generally killed by lysis when the virus leaves the cell
Virulence in viruses
The ability to change their antigen expression is core to the virulence of viruses
Effectively the immune system has to relearn the new antigens
Two main ways this occurs
Antigenic shift
Antigenic drift
Viral clues - gross
Lungs – haematogenous, interstitial lesions
Liver – random necrosis
Viral clues – histo and cyto
Cell enlargement – syncytia versus ballooning, and viral inclusion bodies
Orf – ovine parapox virulence factors
Virulence factors
Viral vascular endothelial growth factor (VEGF)
stimulates capillary proliferation, induces vascular permeability, and enhances epithelial proliferation
Orf virus cytokine IL-10 orthologue
IL-10 suppresses recruitment and activation of neutrophils, monocytes and lymphocytes
Orf virus interferon resistance gene (OVIFNR)
inhibits IFN
ORFV can initiate apoptosis in antigen producing cells and inhibit Bcl-2 to prevent apoptosis of virus infected cells
Rotavirus
Rotavirus directly damages enterocytes-> villus atrophy -> malabsorption and osmotic diarrhoea
And viral proteins and inflammation affect the enterochromaffin cells and enteric nervous system respectively-> secretory diarrhoea and increased motility
Rotavirus is also rare in that it produces a toxin NSP4-> secretory diarrhoea
Retroviruses
Replicate by inserting a DNA copy of their RNA genome into host DNA
Lentiviruses
Maedi-Visna
FIV
HIV/SIV
Oncoretroviruses
FeLV
Mouse mammary tumour virus
Avian leukosis virus (ALV) and reticuloendotheliosis virus (REV)
Bovine leukaemia virus
Enzootic nasal tumour and Jaagsiekte sheep retrovirus
Viral genes
pol – encodes reverse transcriptase and other enzymes
gag – encodes for group-specific nucleocapsid & matrix glycoproteins; detected by antibody-based tests
env – encodes for surface glycoprotein that mediates receptor binding and virus entry into cells; target for neutralizing antibody
Lentiviruses
Infect monocytes/macrophages or CD4 lymphocytes
Immunosuppression (FIV and SIV)
Progressive pneumonia (MV)
Oncoretroviruses
Stimulate neoplastic transformation in host cells
Typically lymphoma
Jaagiekte causes pulmonary carcinomas of type 2 pneumonocytes
Oncogenic viruses of the lymphoid system
Bovine leukaemia virus
Notifiable
Avian leukosis
FIV
The risk for developing lymphoma in FIV-infected cats is fivefold to sixfold higher than in uninfected cats
Intestinal B-cell lymphoma
FeLV
Lymphoma is increased 60-fold in infected cats
Commonly results in T-cell mediastinal/thymic lymphoma
Vaccination has markedly reduced this
Coccidia
Coccidia come in two families- the Eimeriidae (Eimeria, Isospora and Cryptosporidium) and the Sarcocystidae (Toxoplasma, Neospora and Sarcocystis).
The general life cycle of both is ingestion of oocysts from which sporozoites emerge (excystation) and invade enterocytes → multiple rounds of asexual merogony/schizogony in enterocytes, formation of sexual stages (gamonts) that fuse to form oocysts, passed in faeces.
Eimeriidae are only found in the gut.
Sarcocystidae may leave the gut and form cysts in tissues (bradyzoites). In some circumstances these can release fast-dividing tachyzoites that cause necrosis and inflammation (e.g. Toxoplasma, Neospora, Sarcocystis) but the gut cycle is vital for sexual reproduction.
Not all Eimeria spp are pathogenic
Therefore faecal oocyst counts can be difficult to interpret
See other lectures/dry labs
All pathogenic coccidia at some point damage enterocytes
Enterocytes are damaged when mature schizonts rupture and release merozoites
Malabsorption due to villus atrophy
Exudative enteritis and haemorrhagic typhlitis due to epithelial erosion and ulceration
In alpacas, infection with E. macusaniensis can predispose to other infections such as clostridia
Impair intestinal barrier and later permeability-> diarrhoea
Cryptosporidium may produce an enterotoxin resulting in secretory diarrhoea
Sarcocystidae can have a relatively benign existence outside of the GIT
Sarcocystis cysts seen frequently in the muscle, including heart, of ruminants with noassociated inflammation
Disease occurs when
Cysts rupture
Dead-end hosts and/or nervous system infected
S. neurona in horses -> infection of spinal cord
Toxoplasma and Neospora in the brain of dogs
Neospora is also an important cause of abortion in cattle
Trypanosomes
Two major forms of trypanosomiasis:
American trypanosomiasis:Trypanosoma cruzi
African trypanosomiasis: T. congolense, T. vivax, T. brucei brucei
Vector-borne
Four morphologic forms:
Amastigotes (intracellular form): Only form which lacks flagellum; multiplies within mammalian cells – only T.cruzi
Trypomastigotes(blood form):Infective formwhich does not multiply, extracellular; flagellated with characteristic undulating membrane
Trypanosomes are interesting in that they are seen freely within the blood of affected animals
Epimastigotes (intermediate form); found in vectors and multiplies in the midgut
Promastigotes: Rapidly dividing stage
Virulence factors
Two proteins on the surface ofcruziare involved in its entry into macrophages and other host cells
Trans-sialidase:Removes host cell sialic residues and transfers them to a parasite surface protein (Ssp-3), which binds to host cells
Penetrin:Binds extracellular matrix proteins, heparin, heparin sulfate, and collagen and mediates parasite invasion into host cells
Intramacrophage survival due to rapid movement from lysosome to the cytosol
Neuraminidase:Removes sialic acids from host proteins lining the lysosomes and destabilizes this organelle
Hemolysins:Lysosomal acid pH stimulates parasite release of hemolysins, which form pores in and disrupt lysosomal membranes
Immune evasion
Antigenic variation in membrane surface glycoproteins = variant surface glycoprotein (VSG),
Forces the host to constantly redevelop their humoral response and makes making a vaccine virtually impossible
Chronically T. cruzi causes myocarditis
T. evansi and others can cause neurological signs due to inflammation in the brain (meningoencephalitis)
How they cross the BBB is unknown
See SVMPH lecture by Prof Helen Price for more
Fungi
Fungi exist in the environment and as a normal commensals as yeasts or molds (hyphae)
Most pathogenic fungi have both forms in their life cycle= dimorphic
Can be classed as superficial
Candida
Aspergillus
Or systemic
Histoplasmosis, blastomycosis
Coccidiomycosis, cryptococcus
Angio-invasive fungi
Ruminal acidosis
Fusarium, Absdia, Rhizopus and Mucor spp
Virulence factors:
Yeasts have a capsule
In cryptococcus it is very thick
Polysaccharide
Virtually impossible to effectively phagocytose
Some contain melanin which is an antioxidant
inhibits lysosomal digestion if is phagocytosed
Surface antigens
Sequester humoral immunity
Constantly shed
As is typical of pathogens that resist phagocytosis, they cause a chronic inflammatory reaction with granulomatous inflammation
Aspergillosis
Conidia are inhaled and deposited in mucus layer
Normally phagocytosed and killed: if phagocytosis is disrupted (immunosuppresion) then conidia germinate into hyphae and both secrete enzymes that damage the epithelium and expose the basal lamina for easy colonisation and invasion.
Virulence factors:
Gliotoxin - anti-inflammatory, apoptosis of phagocytes
Fumagillin and hevolic acid – antibiotics
Melanin - antioxidant
Grossly, cause grey/black pseudomembranous rhinitis/airways in dogs; may invade underlying bone (necrosis) and also cause granulomas around airways.
Cattle: lungs, placenta, udder.
Horse: guttural pouch.
Cats: Lungs.
Spread systemically by leukocyte trafficking or by angioinvasion - rare
Helminths
Helminths are highly prevalent parasites.
They infect some 2 billion people, nearly one third of the human population.
In animals they are omnipresent.
Helminths establish in a range of tissue and particularly intestinal niches, producing eggs or larvae to infect new hosts.
Can in some cases form stable chronic infections for potentially years.
Their extraordinary prevalence and ability to remain in the body whilst eliciting typically a minimal response, neutralizing immune pathways that would otherwise expel them indicate that they are potentially immunosuppressive and certainly immunomodulatory.
In so doing, they also dampen responses to unrelated bystander specificities, such as allergens and autoantigens, in a manner that may actually benefit the host = hygiene hypothesis, but can potentially reduce vaccination efficacy of unrelated disease.
One of the most well studied is Taenia solium
Patients have
increased IL-10 levels
Decreased TH1 and TH2 cytokine levels
increased Tregs
Bulldog calves
Chondrodysplasia
Signalment:
Dexters and other miniatures
Pathogenesis:
2 different mutations in the aggrecan (ACAN) gene
Gross:
Carried to full term but are usually aborted before the seventh month of gestation
Aborted calves may or may not have hair and are much smaller than normal
Extremely short limbs, usually rotated
Short, domed head with protruding mandible
Cleft palate; and a large ventral abdominal hernia
Tongue is normal size so protrudes from mouth
Histo:
Lack distinct growth plates.
Physeal cartilage consists of densely packed chondrocytes showing no orderly arrangement into columns, and a fibrillar eosinophilic intercellular matrix.
Spider lamb syndrome
Chondrodysplasia
Signalment:
Suffolk and Hampshire sheep
Pathogenesis:
Autosomal recessive
FGFR3
Gross:
Disproportionately long limbs and neck, shallow body, scoliosis and/or kyphosis of the thoracic spine, concave sternum and other sternal deformities
Valgus deformity of the forelimbs below the carpus creating a knock-kneed appearance
Histo
abnormal development of ossification centers in bones that develop by endochondral ossification
Spider lamb syndrome
Chondrodysplasia
Signalment:
Suffolk and Hampshire sheep
Pathogenesis:
Autosomal recessive
FGFR3
Gross:
Disproportionately long limbs and neck, shallow body, scoliosis and/or kyphosis of the thoracic spine, concave sternum and other sternal deformities
Valgus deformity of the forelimbs below the carpus creating a knock-kneed appearance
Histo
abnormal development of ossification centers in bones that develop by endochondral ossification
Chondrodysplasia
a condition characterized by faulty development of cartilage and growth of bone in the ossification centers of bones of nonmembranous origin
bulldog calves
spider lamb
scotish folds and american curls
(Osteo)chondrodysplasia of cats
Signalment
Scottish fold and American Curl
Pathogenesis:
Autosomal dominant fd (fold-eared) gene
Gross:
Irregularity in the size and shape of tarsal, carpal, metatarsal, and metacarpal bones; phalanges; and caudal vertebrae.
Secondary degenerative arthropathy
Histo
defective endochondral ossification in physes and beneath articular cartilage
Physeal dysplasia in cats
Physeal dysplasia in cats (atraumatic slipped capital femoral epiphysis)
Signalment:
male and overweight
Siamese and Maine Coon breeds over-represented
typically young (2-4 years), but older than the age of expected physeal closure (7-9 months)
Pathogenesis:
Unknown
Physeal dysplasia is seen in all growth plates but only the proximal femoral physis fractures, presumably because of the shear forces at that site
Gross:
Head of femur avulsed
Histo
dysplastic growth plates characterized by disorganized clusters of chondrocytes surrounded by abundant matrix
Osteogenesis imperfecta
Signalment
One of the most frequently observed inherited connective tissue disorders of humans, but occurs rarely in domestic animals
Holstein-Friesian, Charolais, Angus
Romney lambs
Beagles, Goldies, Daxxies
Pathogenesis:
Mutations in either the COL1A1 (goldie) or COL1A2 (beagle) genes that code for the α1 and α2 collagen chains, respectively.
The disease in Dachshunds has autosomal recessive inheritance and is caused by a missense mutation in the SERPINH1 gene, which codes for an essential collagen chaperone, HSP47
Gross:
Unable to stand because of marked hypermobility of joints
Dentinogenesis imperfecta
Bones are essentially normal in shape but are extremely brittle
Histo:
Osteoblast numbers and activity vary
Calcified cartilage spicules in the primary spongiosa are lined by only a thin layer of basophilic bone matrix
Little osteoclastic resorption or realignment of trabeculae. Deeper in the secondary spongiosa trabeculae may be lined by woven bone.
Metabolic/nutritional osteodystrophies
Rickets, osteomalacia, fibrous osteodystrophy, and osteoporosis
Distinct morphologic entities with characteristic pathogenesis and lesions, but can occur in combination in the same individual
Further terminology:
Osteopenia = increased radiolucency of bone, but makes no inference as to its quality.
Includes osteoporosis (less bone), and osteomalacia, fibrous osteodystrophy, and osteogenesis imperfecta (less bone and abnormal quality/consistency)
Their cause can vary between species
E.g. calcium deficiency in sheep results in osteoporosis, but in a rapidly growing pig, causes fibrous osteodystrophy.
Pathogenesis
Vitamin D/phosphorus/calcium deficiencies/imbalances
metabolic bone diseases seldom result from a deficiency of a single dietary nutrient. More often, there is either a deficiency of several nutrients or a dietary imbalance in the ratio of calcium to phosphorus
Signalment
Horses fed bran-based diet
Fibrous osteodystrophy
Physiological due to fracture/paraplegia
First lactation dairy cows
Copper deficient farm animals
Malabsorption syndromes – PEG in growing lambs, dogs with IBD
Rapidly growing animals with deficient diets
Rickets and osteomalacia
Metabolic/nutritional osteodystrophies
Rickets (growing animals) and osteomalacia (older animals)
Same thing
Defective endochondrial ossification
rickets in growing therefore issues with growth plates
Pathogenesis
Vitamin D deficiency (nutritional or genetic)
Phosphorus deficiency
Dietary phosphorus deficiency is virtually impossible in carnivores because of the high levels of phosphorus normally present in their rations.
Excess dietary phosphorus, results in nutritional secondary hyperparathyroidism (resulting in rickets) and fibrous osteodystrophy commonly in puppies and kittens
Gross
Most prominent at sites of rapid growth, including metaphyseal and epiphyseal regions of long bones and costochondral junctions of the large middle ribs.
Enlargement of costochondral junctions is a classic feature of the human disease and is referred to as the “rachitic rosary.”
Histo
Persistence of hypertrophic chondrocytes at sites of endochondral ossification, both at physes and beneath articular cartilage, is the hallmark of rickets in histologic preparations
The lesions of osteomalacia are similar to those of rickets but because they occur in adult animals, growth plates are not involved
excessive deposition of matrix where mechanical stimuli are strongest, such as at insertions of tendons and fascia
trabeculae are reduced in size and number, and the cortices are thin and porous. Osteoid covers the trabeculae and lines the expanded Haversian canals. Localized accumulations of osteoid occur at sites of mechanical stress
Fibrous osteodystrophy
Metabolic/nutritional osteodystrophies
Pathogenesis
Persistent elevation of parathyroid hormone
Primary or secondary hyperparathyroidism
Primary - persistent hypercalcemia and hypophosphatemia
Secondary - calcium concentrations are usually either normal or slightly decreased, and depending on the cause, plasma phosphorus concentrations are either normal or increased
Secondary hyperparathyroidism is a much more common cause of fibrous osteodystrophy in animals than primary hyperparathyroidism and may stem from either chronic renal disease or dietary imbalance of calcium and phosphorus.
PTH secretion is stimulated by reduction in plasma ionized calcium, whatever the cause, and if the stimulus persists, then generalized bone resorption results
Horses and goats – high bran/concentrate diets
Carnivores – meat and offal only diets
Gross
Bilateral enlargement of the bones of the skull, affecting both the maxillae and mandibles
Histo
3 key features
osteoclastic bone resorption
fibrosis
osteoblastic deposition of new woven bone
Lesions may vary with state of disease and specific bones involved.
Fibrous osteodystrophy
Metabolic/nutritional osteodystrophies
Pathogenesis
Persistent elevation of parathyroid hormone
Primary or secondary hyperparathyroidism
Primary - persistent hypercalcemia and hypophosphatemia
Secondary - calcium concentrations are usually either normal or slightly decreased, and depending on the cause, plasma phosphorus concentrations are either normal or increased
Secondary hyperparathyroidism is a much more common cause of fibrous osteodystrophy in animals than primary hyperparathyroidism and may stem from either chronic renal disease or dietary imbalance of calcium and phosphorus.
PTH secretion is stimulated by reduction in plasma ionized calcium, whatever the cause, and if the stimulus persists, then generalized bone resorption results
Horses and goats – high bran/concentrate diets
Carnivores – meat and offal only diets
Gross
Bilateral enlargement of the bones of the skull, affecting both the maxillae and mandibles
Histo
3 key features
osteoclastic bone resorption
fibrosis
osteoblastic deposition of new woven bone
Lesions may vary with state of disease and specific bones involved.
Vitamin A toxicity
Toxic osteodystrophies
Signalment- Cats fed liver
Pathogenesis
Inhibits chondrocyte proliferation and reduces RNA and protein synthesis.
Lysis of matrix may be the result of destabilization of lysosomal membrane
Gross
Osteophyte formation is the hallmark -> deforming cervical spondylosis
Histo
Physeal lesions -
reduced chondrocyte proliferation and reduced size of hypertrophic chondrocytes, resulting in narrowing of growth plates.
Osteoporosis-
decreased numbers of osteoblasts and fewer, thinner osteoid seams
Lead toxicity
Toxic osteodystrophies
Pathogenesis
Impaired osteoclastic resorption
Osteoclasts may contain acid-fast intranuclear inclusions
Gross
A band of sclerosis, referred to as a “lead line” or
Histo
Persistence of mineralized cartilage trabeculae in the metaphysis
Bacterial osteomyelitis
Bacteria infect bone by 3 routes:
hematogenous,
local extension
implantation.
Hematogenous osteomyelitis is very common in animals, especially young horses and ruminants.>70% will also have septic arthritis (joint ill).
Duringbacteraemia, there is a predilection for bacteria to localize to sites of active endochondral ossification within themetaphysesand epiphyses of long bones and vertebral bodies
Some bacteria have a predilection for bone. Staphylococcus aureus, for example, can invade osteoblasts.
Trueperella(Arcanobacterium) pyogenes is the most common causative organism in vertebral osteomyelitis in large animals, but a range of other bacteria may be involved. These include: Escherichia coli, Salmonella enterica serovar Typhimurium, staphylococci, streptococci, andRhodococcusequiin foals; Fusobacteriumnecrophorumin calves;Mannheimiahaemolytica, F.necrophorum, and staphylococci in sheep; andErysipelothrixrhusiopathiae, staphylococci, and streptococci in pigs. In dogs, vertebral osteomyelitis has been linked to migration of plant material. In cats, bite wounds are the most likely route of infection.
Lumpy jaw-
Mandibular osteomyelitis in the cow
Aetiology-
Actinomycesbovis
Gross
“Honeycomb” appearance caused by pockets of inflammatory tissue surrounded by reactive bone.
Histo:
Colonies of A.bovissurrounded by characteristic brightly eosinophilic clubs ofSplendore-Hoepplimaterial and suspended in a dense neutrophilic exudate.
Atrophic rhinitis of pigs-
Aetiology
mediated by bacterial toxins produced by Pasteurella multocida and Bordetella bronchiseptica.
Pathogenesis
These toxins inhibit osteoblast differentiation and stimulate osteoclast activity, resulting in bone loss
Viral infection of bone
Some viruses directly infect osteoclasts:
canine distemper
bovine viral diarrhoea
Resulting in an acquired impairment of osteoclastic resorption of bone during growth and continued endochondral ossification resulting in:
A dense band of grossly appreciable sclerotic bone at the metaphysis of developing bone
Often directly subjacent to the growth plate
Referred to as a growth retardation lattice
Resulting in an acquired impairment of osteoclastic resorption of bone during growth and continued endochondral ossification resulting in:
A dense band of grossly appreciable sclerotic bone at the metaphysis of developing bone
Often directly subjacent to the growth plate
Referred to as a growth retardation lattice
Avascular necrosis of the femoral head
Legg-Calves-Perthes disease
Signalment
Westies 4-8m
Pathogenesis
Inherited as an autosomal recessive trait
Ischaemia
Delayed incorporation of vessels supplying the femoral head into protective fibro-osseous canals?
Gross
Fracture and collapse of the necrotic trabecular bone and flattening of the femoral head
Histo
Subchondral epiphyseal osteonecrosis
avulsion
An avulsion fracture occurs when there is excessive trauma at sites of ligamentous or tendinous insertions and a fragment of bone is torn away
microfractures
Microscopic fractures of individual trabeculae, or localized segments of cortical bone, also occur and are referred to as microfractures. Displacement of the bone ends are referred to as infractions.
Fracture repair consists of 4 overlapping processes:
Inflammation
Soft callus formation
Hard callus formation
Remodelling
Fracture callus
Histologic appearance depends on the phase of bone repair and alignment or not of the fracture ends
Histological appearance will vary but is typically defined as:
cartilage undergoing endochondral ossification composed of tightly packed chondrocytes in a basophilic matrix with densely packed fibroblasts and collagen fibres
Additionally may see
bone fracture
blood clot
necrotic bone
periosteal and endosteal proliferation
high numbers of osteoblasts
The key microscopic feature of reactive bone formation is that of well-ordered maturation.
Primary tumours of the skeleton
beningn-
Osteoma
Chondroma
Fibroma
Multilobular tumour of bone
malignant-
Osteosarcoma
Chondrosarcoma
Fibrosarcoma
Osteosarcoma
Cell of origin unclear
Mesenchymal stem cells
Osteoblast
Osteocyte
Common in dogs and cats and the most common bone tumour (95%.
Typically, appendicular/long bones (away from the elbow, towards the knee), but also ribs and extra-axial (mammary).
Aggressive, painful and quick to metastasise (lungs).
Gross
Grey-white gross and contain variable amounts of mineralized bone.
Large, pale areas surrounded by zones of haemorrhage (areas of infarction).
Neoplastic tissue will fill the medullary cavity
Does not penetrate articular cartilage and therefore does not invade the joint space.
Cortical bone is usually destroyed
Neoplastic cells penetrate and undermine the periosteum and can extend outwardly as an irregular lobulated mass (“sunburst” pattern on radiograph)
Destruction of cortical bone results in pathological fractures
Histo
Unencapsulated, infiltrative, densely cellular neoplasm composed of spindle cells
Production of varying amounts of eosinophilic homogeneous to fibrillar matrix (osteoid) and reactive (nonneoplastic) periosteal bone
Fibrovascular matrix.
Moderate to brisk mitotic rate and some anisokaryosis and anisocytosis.
Occasional multinucleated giant cells that resemble osteoclasts.
Fibrosarcoma
Fibrosarcomas of the appendicular skeleton are much less common than osteosarcomas
That said, fibrosarcomas are the third most common tumour of cats
these are typically soft tissue sarcomas, and injection site-associated (see oncology next year)
Fibrosarcomas also relatively common in dogs and cats associated with the mouth
See oral pathology lecture
Histo appearance is typical of a mesenchymal tumour
Fusiform cells and nuclei
Proliferative non-neoplastic lesions of the bone
Hypertrophic osteopathy-
Marie’s Disease
Secondary to (typically) intra-thoracic pathology but also reported in association with bladder tumours and hyperadrenocorticism
Unclear pathogenesis
Characterized by progressive, often bilateral, periosteal, new bone formation of the distal limbs
Bone cysts-
Most common in the horse
Aneurysmal, simple (unicameral) and subchondral
Also dentigerous cysts
Osteochondromas (cartilaginous exostoses)
Metastatic bone tumours
Mammary, liver, lung and prostatic carcinomas preferentially metastasise to bone.
Ribs, vertebrae and proximal long bones in dogs
Clinically silent pulmonary carcinomas in cats metastasize to the third phalanx, causing destruction of the nail bed epithelium (“felinelung-digitsyndrome”).
Atrophy
Pathogenesis
Denervation- Types 1+2
Disuse- Predominantly Type 2
Endocrine- Predominantly Type 2
Malnutrition - Predominantly Type 2
Congenital- Predominantly Type 1
Immune-mediated myositis
Predominantly reported in dogs, but also cattle
Pathogenesis:
Canine Masticatory myositis:
Canine masticatory muscles have a unique myosin isoform (2M)
Various bacterial infections may lead to misdirected antibodies against type 2M -> muscle fibre necrosis
Gross:
Bilateral severe masticatory muscle wastage
Histo:
Multifocoal polyphasic myofiber degerenation and necrosis
Lymphocytes predominate with various eosinophils
Localised extraocular form in Goldies
Localised tongue form in Japanese Welsh corgis
Polymyositis in dogs is typically associated with severe underlying systemic disease such as lupus, lymphoma and thymoma
Feline disease associated with FIV
Cattle form is eosinophil rich and may be associated with sarcocystis
Bacterial myositis
Wooden tongue
Cattle
Actinobacillus lignieresii
Blackleg
Clostridium chauvoei
Necrosis, gas formation
Nutritional myopathy
White muscle disease
Pathogenesis-
Vit E/selenium deficiency
Stress-associated myopathies
Porcine stress syndrome (PSS) or malignant hyperthermia
Pathogenesis
Defective calcium channel
Gross-
Pale soft exudative pork
Capture myopathy
Exertional rhabdomyolysis
Mild will just see increased CK/AST/LDH
Myoglobin is toxic to renal tubular cells
Myoglobinuria
Renal failure in severe cases
congenital pathologies of muscle
Double muscling
Pathogenesis
Defect in myostatin
Muscles are hyperplastic and hypertrophic
Muscular dystrophy
Pathogenesis
Defect in dystrophin
X-linked
Splay-leg
Hyperkalaemic periodic paralysis
Pathogenesis
Defect in sodium channel
Polysaccharide storage myopathy
Pathogenesis
Defect in glycogen handling
Phagocytes
Neutrophils
Macrophages
Dendritic cells
(B-cells)
the complement system
Component of serum
Roles:
Chemotactic
Increase vascular permeability
Opsonisation
Formation of membrane attack complex (MAC)
Cytokines and chemokines
Proteins, peptides and glycoproteins
Typically only produced by leukocytes, but also fibroblasts and endothelial cells
Interleukins (IL-), interferons (IFN-), tumour necrosis factor (TNF)
Modulate functional expression of inflammatory cells in acute inflammatory response
Also major roles in haematopoiesis and adaptive immunity
Grouped into:
Hematopoietic growth factors – IL-3, G-CSF, GM-CSF +/- IL-9, IL-11 and stem cell factor
Inflammatory mediators – including acute phase reactants and natural immunity, IL-1, IL-6, TNF α and β
Chemotactic – IL-8
T lymphocyte proliferation, activation and differentiation – IL-2, 4, 5, 7, 9, 10, 12, and 17 through 29
Biochemically, cytokines divided into type I or type II
Type I – 4 α helices
Type II - 6 α helices
Variety of stimuli invoke cytokine expression and wide range of receptors
Chemokines:
Smaller
Type of cytokine that primarily promote leukocyte chemotaxis and migration across capillaries and venules
Produced by all nucleated cells
Dendritic cells
Key antigen presenting cells (APCs)
Monocyte-macrophage lineage/ monocyte phagocytic system
special type of immune cell that is found in tissues, such as the skin, and boosts immune responses by showing antigens on its surface to other cells of the immune system. A dendritic cell is a type of phagocyte and a type of antigen-presenting cell (APC).
Types of T helper-lymphocytes
T helper-cells (CD4) can differentiate into different functions
Th1, Th2, Th17 and T-regs
T-cells can differentiate into different functions
TH1, TH2 and T-regs
TH1 lymphocytes are activated by IL-12 and IL-18 and produce primarily IL-2, IFN-γ, and TNF-β to direct a cell-mediated immune response.
TH2 lymphocytes are activated by IL-4 and produce primarily IL-3, IL-4, IL-5, IL-6, IL-10, and IL-13 to direct a humoral immune response.
Immunopathogenesis of FIP
Immunity to feline infectious peritonitis (FIP), when it occurs, is largely cell-mediated
Production of antibodies is counterproductive
Antibodies enhance the uptake and replication of FIPVs in macrophages
Also contribute to a type III hypersensitivity (antibody-mediated) vasculitis
Reason why the vaccination made the disease worse
It is also assumed that much of the pathology occurring in FIP is associated with how macrophages respond to viral infection and how the immune system of the host responds to the infected cells.
The effusive form of FIP results from a failure to mountT-cellimmunity in the face of a vigorous B cell response.
At the opposite extreme, cats that resist disease presumably mount a vigorous cell-mediated immune response that is able to overcome any negative effects of antibodies.
Cats with the dry form of FIP represent an intermediate state involving a cellular response that is partially effective in containing the virus to a relatively small number of macrophages in a few focal sites within specific target organs.
The two forms of FIP are somewhat interchangeable; when it has been observed in experimental infection, the dry form always follows a brief bout of effusive disease.
In the terminal stages of naturally occurring dry FIP, immunity can completely collapse and the disease reverts to a more effusive form.
Antibodies = secreted immunoglobulins
Under appropriate conditions, B-cells mature to plasma cells
Plasma cells produce immunoglobulins
Five different classes of antibodies (in mammals):
IgG
IgM
IgA
IgE
IgD
The class of immunoglobulin secreted by B cells and plasma cells depends on their location.
Cells located in lymphoid organs within the body secrete IgM and IgG, whereas cells located on mucosal surfaces mainly secrete IgA and/or IgE.
IgG is the most abundant immunoglobulin found in the bloodstream and clostrum.
IgM is usually confined to the bloodstream because it is a very large molecule with much more antigen binding capacity compared with the smaller IgG, which can easily go into interstitial spaces.
IgA is produced by B cells and plasma cells located on mucosal surfaces. Most abundant in milk.
IgE is produced locally by plasma cells and then binds with a very high affinity to tissue mast cells. Involved in allergy (see later).
Passive transfer of immunoglobulins
Occurs from dam to neonate via colostrum.
IgG.
Enterocyte only able to take up IgG in first 24-36hours of life.
Suboptimal transfer occurs is approximately 35% of dairy calves.
Failure of passive transfer (FPT)
Predisposes neonate to systemic infections
Joint ill
Can be measured in two ways
Indirect
Serum total protein
Zinc sulphate turbidity test
GGT levels
Direct
ELISA (snap test) - foals
Lymphoid organs
Primary lymphoid organs
Antigen-independent formation of lymphocytes
Thymus
Bursa of Fabricius
Bone marrow
Peyer’s patches (in ruminants)
Foetal liver
Secondary lymphoid organs
Antigen-dependent maturation of lymphocytes
Spleen
Tonsil
Peyer’s patches
Lymph nodes
Tertiary
MALT/GALT/BALT
Sampling of pathogens at epithelial surfaces
Immunodeficiency
Immunodeficiency can be defined as a relative or absolute inability of the immune system to protect the host from infection
Primary or secondary
Primary-
Genetic deficiency in a component of the immune system
Secondary-
Exogenous cause of defective immunity
Infectious
Radiation/chemotherapy
Age-related
Nutritional
Severe combined immunodeficiency disease
SCID
One of the best well known immunodeficiencies
Family of genetic defects-
X-linked
Autosomal recessive
Sporadic
Affects adaptive immunity
T or T and B - cell
Deficiencies in both humoral and cellular mediated responses
Horses
Arabian
Autosomal recessive
Lymphopaenia and agammaglobulinaemia
Death due to secondary infections
In mice this is selectively bred for for experimental purposes
Gross pathology includes marked thymic hypoplasia
Chediak-Higashi syndrome
Defective ability to release intracellular granules and reduced ADP
Affects
All granulocytes
Melanocytes
Platelets
Leukocyte adhesion deficiency
Humans, dogs (Irish Setters) and cattle (Holsteins)
CD18 deficiency
High numbers of neutrophils circulating, but cannot migrate through the endothelium
Fell pony syndrome
Foal immunodeficiency syndrome (FIS), previously known as Fell Pony syndrome
Autosomal recessive
Severe anaemia and B cell lymphopenia
Cyclic neutropenia
Grey collie syndrome/cyclic haematopoiesis
Autosomal recessive
Every 10-12 days the neutrophil count drops dramatically
Death before 6 months
Secondary immunodeficiencies - infections
Infections primarily cause immunodeficiency in three ways
Destruction of a physical barrier
Consumption of immune factors
Direct infection/destruction of immune cells and/or tissues
Canine parvovirus and feline panleukopaenia
Examples of all three
Apoptosis of enterocytes
Destruction of the gut/bloodstream barrier
Virulent
Lymphocyte and/or precursor infection
Resulting in diarrhoea, secondary bacterial infections, panleukopaenia
Inflammation and infection can result in autoimmunity in 5 keys ways
Upregulated expression of costimulators on APCs that present self-antigens
Molecular mimicry
Some infectious agents express antigens that have the same amino acid sequences as self-antigens, leading to activation of self-lymphocytes
Polyclonal B cell activation
Tissue injury
Causes self-antigen release.
These antigens are may also be altered by injury
Stimulate production of cytokines
NB: infection can also protect against allergy/autoimmune disease. See POP Infection – protozoa, fungi and helminths lecture
Hypersensitivity
Definition
Altered and injurious immune reactivity to a specific antigen in a sensitised host
General features:
Elicited by antigens
endogenous or exogenous
microbial and nonmicrobial
Imbalance of effector and control mechanisms
Often associated with particular susceptibility genes
Tissue injury mechanism same in hypersensitivity as in normal defence effector mechanisms
Just poorly controlled, excessive or misdirected
Sensitisation and effector phases
allergic
cytotoxic
immune complex
delayed
Type 1 Hypersensitivity
“Allergy”
Rapid reaction in a previously sensitised individual triggered by binding of an environmental antigen to IgE antibody on mast cell surface
Most caused by excessive Th2 responses; stimulate IgE production and promote inflammation
Systemic (injection, ingestion) or local reaction
Two phases:
1) Immediate (mins hours) – vasodilation, vascular leakage, smooth muscle spasm, gland secretion
2) Late (2-24 hours days) – tissue infiltration with eosinophils, neutrophils, basophils, monocytes, CD4+ T cells AND tissue destruction (mucosal epithelial)
Mediators of Immediate Hypersensitivity
Pre-formed (primary) mediators stored in granules
Vasoactive amines – e.g. histamine smooth muscle contraction, ↑vascular permeability, ↑mucus (nasal, gastric, bronchial)
Enzymes – e.g. neutral proteases (chymase, tryptase), acid hydrolases. Cause tissue damage and lead to generation of kinins and activate complement components (C3a)
Proteoglycans – e.g. heparin and chondroitin sulfate. Package and store the amines in granules
Lipid mediators - membrane phospholipids arachidonic acid leukotrienes (5-lipoxygenase), prostaglandins (COX)
Leukotrienes – C4, D4 (vasoactive) and B4 (neutrophil chemotactic)
Prostaglandin D2
Platelet-activating factor
Cytokines – many
Leukocyte recruitment - TNF, IL-1, chemokines
Amplify Th2 response – IL-4
Histamine-releasing factors
Development of Allergies
Susceptibility genetically determined= “atopy”
Several genes
Higher serum IgE, more IL-4-producing Th2 cells
Environmental factors – pollutants, viral infections, bacterial skin infections
20-30% of immediate reactions triggered by non-antigenic stimuli e.g. temperature extremes, exercise, and do not involve IgE or Th2 cells = “nonatopic allergy”
Systemic Anaphylaxis
Vascular shock, oedema, difficulty breathing
Local Immediate Hypersensitivity Reactions
Reaction to e.g. pollen, animal dander, food
Cause urticarial, allergic rhinitis, bronchial asthma, etc.
Acute allergic reaction (local hypersensitivity)
defined as an acute onset of illness and evidence of generalized mediator release restricted to cutaneous findings alone
erythema, pruritis, urticaria, or angioedema without any other systemic signs.
Systemic (generalized) hypersensitivity reactions
classified by the severity of the systemic reaction based on a grading system
Mild
skin/mucosal tissue without involvement of other organs but having some indication of a generalized component (eg, fever)
Moderate
systemic involving 2 or more organ systems, animals are normotensive and without evidence of neurologic compromise.
Severe
evidence of neurologic compromise (collapse or syncope) or hypotension
Moderate and severe systemic hypersensitivity reactions are classified as anaphylaxis
In human medicine, serum mast cell tryptase can be measured
Post mortem findings
Acute cardiogenic failure
Marked diffuse vascular congestion of lungs, liver, intestine
Marked diffuse alveolar oedema of the lungs
Histo
Moderate hydropic degeneration of centrolobular to midzonal hepatocytes
In humans, histopathology of lungs will show increased numbers of mast cells
What are mast cells?
Part of the innate immune system
A granulocyte
Contains cytoplasmic granules
Mast cells are normally distributed throughout connective tissue adjacent to blood vessels and lymphatics within the skin and mucosa
When exposed to inciting agent and IgE, degranulate to release histamine
Histamine is a vasoactive amine-> vasodilation and increased permeability of vessels
Type 2 Hypersensitivity
Antibodies react with antigens on cell surfaces or in ECM destroy these cells, trigger inflammation or interfere with normal function
Antigens endogenous or exogenous (drugs, microbial protein)
IgM and IgG
Occur within hours after exposure in sensitized host
Three mechanisms:
Opsonization and Phagocytosis - IMHA
Inflammation- Glomerulonephritis(not all), Vascular issues and rejection in organ grafts
Dysfunction- Myasthenia gravis
Type 3 Hypersensitivity
Antigen-antibody complexes
Inflammation at site of deposition-
Typically vascular
Examples-
Blue-eye in canine adenovirus (hepatitis)
FIP
Type 4 Hypersensitivity
CD4+ T cell-Mediated Inflammation
cytokines produced by the T cells induce inflammation that may be chronic and destructive
Delayed type hypersensitivity
Th1 and Th17 cells contribute to organ-specific diseases in which inflammation is a prominent aspect of the pathology
Th1 – activates macrophages
Th17 – activates neutrophils
Tuberculin skin reaction
Immune tolerance
Self tolerance = lack of responsiveness to own antigen
Antigen receptors of lymphocytes are generated by somatic recombination of genes in a random fashion. Receptors recognising self antigens are constantly generated
These self-recognising lymphocytes must be “taught” to not react to self antigens
Occurs centrally or peripherally:
Centrally- Thymus and bone marrow
Peripherally- Anywhere there are APCs
Occurs in four ways-
Centrally T and B cells can be deleted (apoptosis)
T-cells can also be delete peripherally
Or T-cells can be pushed toward becoming T-regs
Peripherally T and B cells can become anergic
T-regs locally supress the immune response
Immunoprivileged sites
Some sites do not communicate with blood/lymph:
And/or have minimal MHC expression
Examples: testes, eye & brain
Because of this, the thymus does not need to “tell” lymphocytes not to react to them
Therefore, if trauma or leakage of this tissues does expose them to the immune system, the immune response is typically marked and chronic- Examples: post-traumatic orchitis
Conversely, it is difficult to elicit an immune response to antigens introduced into these sites
More on the eye-
Cells of iris and ciliary body also produce inhibitory cytokines
Corneal endothelium and retina express practically no MHC class 1- Inability to activate cytotoxic T-cells
Mechanisms of autoimmunity
- Defective tolerance
Breakdown of the previously discussed self-tolerance mechanisms.
Genetic – complex multigenic
MHC alleles - Increased expression or persistence of self antigens or changes to self antigens
These antigens undergo structural changes as a result of cellular stress or injury, or from enzymatic modifications.
These changes lead to the display of antigenic epitopes that are not expressed normally. The immune system may not be tolerant to these epitopes. - Inflammation/infection
The innate immune response creates a strong stimulus for subsequent activation of lymphocytes & generation of an adaptive immune response.
Microbes or cell injury can induce inflammatory reactions that resemble the innate immune response, inducing autoimmune disease.
Lupus
Lupus erythematosus occurs in two distinct forms in animals:
Systemic lupus erythematous (SLE)- which affects multiple tissues, occasionally including the skin
Cutaneous or discoid lupus erythematous (CLE/DLE)- lesions are localized to the skin.
SLE:
Recognized in mice, humans, non-human primates and various domestic animals.
Pathogenesis-
Loss of B- and T-cell tolerance to self-antigens
Autoantibodies against a range of nuclear and cytoplasmic components of the cell, including histones, double-stranded DNA, nonhistone proteins bound to RNA, and nucleolar antigens.
Incites a type 3 hypersensitivity reaction, but also type 2 and 4 depending on type
Definitive cause unclear
Pathophysiology-
Systemic inflammation
Autoantibodies and self-antigen complexes deposit within glomeruli, blood vessels, skin and joints,
A wide spectrum of clinical presentations
Affected patients may exhibit a combination of renal disease (glomerulonephritis, interstitial nephritis, vasculitis, and proteinuria), polyarthritis, skin lesions, hematologic disorders, respiratory, or neurologic dysfunction.
In domestic animals, lupoid skin disorders, such as CLE, are most frequently seen in the dog, often localized to the nose:
Gross lesions range from alopecia to scaling to ulcerative dermatitis
Depigmentation of the nose is classic of DLE but not pathognomonic
Histopathology is diagnostic
Interface dermatitis
Diagnosing SLE
Fever
Nonerosive polyarthritis -
Characterised by exudation of neutrophils and fibrin into synovial membrane + perivascular cuffing by mononuclear cells
Primarily affects intervertebral, carpal, tarsal, temporomandibular
Glomerulonephritis-
Deposition of immune complexes in glomerulus, blood vessels & basement membrane of renal tubules
Persistent proteinuria (>0.5g/dL)
Variable from slight mesangial alterations to diffuse proliferative lesions
Mucocutaneous lesions
Skin lesions:
Non-specific in the dog
Affects face, ears & digital extremities
Erythema, ulceration & exfoliative dermatitis
Lymph node & splenic enlargement
Haematologic abnormalities:
IMHA and/or IMTP – both together is called Evan’s syndrome
Lymphopenia with increased CD4:CD8 ratio
(SLE <6:1, normal <2:1)
Antinuclear antibody (ANA) titre commercially available in dogs
Pemphigus
Pemphigus are a group of autoimmune skin diseases
Pathophysiology:
Immune reaction agains anchoring collagens desmosomes, hemidesmosomes, etc
Gross pathology:
pustules, vesicles, bullae, erosions, ulcers
Histopathology:
Acanthosis = epidermal thickening (not specific)
Acantholysis = loss of adhesion between epithelial cells (relatively specific)
Characterised into different types by location of epidermal damage
P. foliaceous = superficial (stratum granularis)
P. vulgaris = deeper (stratum basal)
Subepidermal forms include: mucous membrane pemphigus, bullous pemphigoid, epidermolysis bullosa
Polycystic kidney disease
Single gene disorders – autosomal dominant
Only one mutated allele is required
One parent heterozygous will result in 50% affected offspring
Signalment-
Persian cats and Bull Terrier dogs
Pathogenesis-
Polycystin-1 and/or 2 mutated
Modify cilia function, cell proliferation and migration-Tubular cell proliferation and fluid secretion
Clinical signs-
Assoc. with renal failure
PUPD
Clin path-
Low USG
Azotaemia
Gross pathology-
Bilaterally irregular enlarged to shrunken kidneys depending on chronicity
Large cysts interspersed by firm pale tan to cream/white (fibrotic) areas
In cats cysts are also seen in the liver and pancreas
Single gene disorders – autosomal dominant
Only one mutated allele is required
One parent heterozygous will result in 50% affected offspring
Polycystic kidney disease
Lysosomal storage diseases
Single gene disorders – autosomal recessive
Two mutated alleles are required
Both parents heterozygous will result in 25% affected offspring
Signalment-
Young animals, any species
Pathogenesis-
Result from the lack of any protein that is necessary for the normal functioning of lysosomal degradation pathways.
Clinical signs-
Vary depending on which part of the CNS affected.
Progressive.
Ataxia, dysmetria, head and limb tremors
Gross-
Typically none
Potentially increased cerebellar weight if primarily affects cerebellum
Histopathology
See image
Clin path-
May see accumulated material in macrophages in blood or CSF
Diagnosis-
Urinalysis for GAGs
Biopsy/PM tissue material – ultrastructure and/or enzyme assay
Dried blood spots – enzyme assay
Single gene disorders – autosomal recessive
Two mutated alleles are required
Both parents heterozygous will result in 25% affected offspring
Lysosomal storage diseases
Duchenne’s muscular dystrophy
Single gene disorders – X-linked
Mutated gene on the X-chromosome-
Usually recessive
Males worse affected
Signalment-
Middle aged dogs
Goldies
Pathogenesis-
Dystrophin gene
Lack of this gene increases the susceptibility of the muscle fibres to repeated bouts of necrosis, regeneration, and fibrosis
Clinical signs and gross pathology-
Progressive muscle atrophy
Resultant weakness in diaphragm impairs respiration and may result in hiatal hernia
Histopath-
Single gene disorders – X-linked
Mutated gene on the X-chromosome
Usually recessive
Males worse affected
Duchenne’s muscular dystrophy
X-chromosome monosomy
Rare
Chromosomal disorders
Turner-like syndrome
Horses, pigs
XO
Clinical appearance-
Can go unnoticed until breeding failure
Small body size, poor conformation, angular deformities
Small and inactive ovaries with an underdeveloped reproductive tract
Diagnosis-
Karyotyping
Chromosomal disorders
Rare
X-chromosome monosomy
Turner-like syndrome
Horses, pigs
XO
Complex multigenic disorders
Poorly characterised
Humans
Diabetes type 1
Systemic lupus erythematosus
The aetiology of the autoimmune disease systemic lupus erythematosus (SLE) is considered to be a combination of multiple genetic and environmental factors whose amalgamation breaches the threshold of immune tolerance.
Neoplasia
new growth due to irreversible genetic changes rendering them unresponsive to ordinary cellular controls
Other terms:
Mass-
Enlargement of tissue
Neoplastic or otherwise (granuloma)
Tumour-
Swelling/growth
Describes clinical appearance
Cancer-
Crab
Describes infiltrative behaviour
Always denotes malignant neoplasms
Oncology = study of neoplasia
steps involved in cancer formation
Initiation: first step of carcinogenesis: introduction of an irreversible genetic change into normal cells by action of mutagenic initiating agent e.g. chemical or physical carcinogens that damage DNA. Mutation induction also requires mispairing of the DNA lesion to produce altered complementary DNA strand thus at least a single round of DNA replication is necessary for genetic change to become permanent. Initiated cells are morphologically normal
Promotion: second stage; outgrowth of initiated cells in response to selective stimuli (=promoting agents) that drive proliferation. Promoters are not mutagenic but create a proliferative environment with reversible effects. A benign tumour is the end product of the promotion phase
Progression: final stage where a benign tumour evolves into an increasingly malignant tumour = malignant transformation (irreversible change that involves genetic and epigenetic changes). Hallmarks of progression = genetic instability and increasing tumour cell heterogeneity
Definitions-
Mutagens: agents that cause mutations
Carcinogens: agents that cause cancer
Complete Carcinogens: An agent that is an initiator and promoter, e.g. radiation
The latent period is the time before a tumour becomes clinically detectable
Smallest clinically detectable mass is usually ~1cm and contains ~10^9 cells
(need 30 rounds of cell division)
steps involved in cancer formation-Initiation:
first step of carcinogenesis: introduction of an irreversible genetic change into normal cells by action of mutagenic initiating agent e.g. chemical or physical carcinogens that damage DNA. Mutation induction also requires mispairing of the DNA lesion to produce altered complementary DNA strand thus at least a single round of DNA replication is necessary for genetic change to become permanent. Initiated cells are morphologically normal
steps involved in cancer formation- promotion
second stage; outgrowth of initiated cells in response to selective stimuli (=promoting agents) that drive proliferation. Promoters are not mutagenic but create a proliferative environment with reversible effects. A benign tumour is the end product of the promotion phase
steps involved in cancer formation- Progression:
final stage where a benign tumour evolves into an increasingly malignant tumour = malignant transformation (irreversible change that involves genetic and epigenetic changes). Hallmarks of progression = genetic instability and increasing tumour cell heterogeneity
P53
controls expression nad activation of protiens involved in the cell cycle
acts as a tumor suppressor, which means that it regulates cell division by keeping cells from growing and dividing (proliferating) too fast or in an uncontrolled way.
activated p53 can send the cell down numerous pathways- sensecence, repair, apoptosis
defective p53 may lea to uncontrolled neoplasms in the event cells are exposed to mutinagens and carcinogens
Vet example: Aflatoxin B1 produced by Aspergillus sp. causes mutation in TP53 gene causing G:C T:A at codon 249. Result is arginine to serine substitution in p53 protein. Strong association between hepatocellular carcinoma and Aflatoxin B1
Single gene disorders
Single gene disorders of somatic cells
NOT heritable
Tumorigenesis – see cancer lectures
Congenital disorders
Rare
Single gene disorders of germ cells
Heritable
Autosomal dominant
Autosomal recessive
X-linked
Single-gene disorders of mitochondria
Rare
Mitochondrial encephalopathies (Huskies) and myopathies (horses)
Single gene disorders of somatic cells
NOT heritable
Tumorigenesis – see cancer lectures
Congenital disorders
Rare
Single gene disorders of germ cells
Heritable
Autosomal dominant
Autosomal recessive
X-linked
Single-gene disorders of mitochondria
Rare
Mitochondrial encephalopathies (Huskies) and myopathies (horses)
Benign tumours
Morphology-
Tumours resemble normal parenchymal cells
Well-differentiated adenocarcinomas of the thyroid form normal-appearing follicles
Squamous cell carcinomas may contain cells that appear identical to normal squamous epithelial cells
Functional-
Retain a lot of normal function
Benign neoplasms and well-differentiated carcinomas of endocrine glands frequently secrete hormones characteristic of their origin, e.g. thyroid adenoma
Well-differentiated squamous cell carcinomas of the epidermis synthesises keratin
Sertolli cell tumours overproduce oestrogen- Paraneoplastic syndrome
Malignant tumours
Morphology-
Lose resemblance to normal cells
Criteria of malignancy
Anisocytosis – variation in cell size
Anisokaryosis – variation in nuclear size
Pleomorphism – variation in cell shape
Karyomegaly – large nuclei, increased N:C ratio
Multiple nuclei
Mitoses – indicative of rapid growth. Atypical/bizarre mitoses may be present
Loss of polarity – disturbed orientation
Large central areas of ischaemic necrosis
Functionality-
Lost function
May gain new and unanticipated functions
Expression of foetal proteins or other proteins not normally found in corresponding normal adult cells
May produce unexpected hormones- parathyroid-like hormone in anal sac gland carcinoma
paraneoplastic syndrome
Malignancy
the occurrence or potential to metastasise
Metastasis
Cancer cells break away from their site or organ of origin to invade surrounding tissue and spread to distant body parts.
Some cancers rarely metastasise
Criteria of malignancy typically correlate with risk of metastasis
Lymphomas and leukaemias are often disseminated at diagnosis and are always taken to be malignant
hence the interchangeable terms lymphoma and lymphosarcoma
Due to our clinical knowledge, we can predict risk in some tumours in some species in some locations
Melanoma in dog mouth is always considered malignant
Staging can confirm metastasis (see MCT lecture)
The process of metastasis
Loosening of intercellular junctions
Loss of cell to cell adhesion is a key first step
Downregulation of e-cadherins
Degradation of the basement membrane-
Production of proteases/collagenases
Adhesion to ECM-
Upregulation of n-cadherins
Migration/locomotion-
Autocrine motility factor
Response to scatter factor
Intravasion-
Tumour associated macrophages
Angiogenesis
Tumour emboli-
Escape from anoikis
Extravasion-
Chemokines
Lymphatic spread
Most carcinomas and some sarcomas go this way
Lymph node involvement largely depends on pre-existing routes of normal lymphatic drainage.
e.g. adenocarcinoma of intestine -> mesenteric LN first
However, regional LN’s may be bypassed, so-called skip metastasis—because of venous-lymphatic anastomoses or because inflammation or radiation has obliterated lymphatic channels.
Recent studies suggest that lymphatic spread does not occur in an orderly fashion and that metastasis to regional lymph nodes indicates that systemic spread has likely already occurred.
Haematogenous
spread
Sarcomas use this more than carcinomas
Generally invade veins more than arteries because of thinner walls
Tumour cells invading veins, go to vena cava, then pass through heart and lodge in capillary beds particularly of lungs
Tumour cells that invade portal vein tend to lodge in liver.
Pheochromocytomas has a notable predilection for invading veins - likes to invade adjacent caudal vena cava
Transcoelomic spread
Aka ‘seeding’
Tumours that arise on surface of abdominal or thoracic structure.
Spread over visceral and parietal surfaces
e.g. ovarian and pancreatic adenocarcinomas – multiple tumour masses throughout the abdomen. This condition is termed carcinomatosis.
Difficult to treat, generally fatal
Mast cell tumours
Mast cells originate from hematopoietic precursors in bone marrow that undergo differentiation and maturation in tissues under the influence of cytokines
Have a specific KIT receptor for the stem cell factor, also known as CD117
Why they become neoplastic is not completely understood
Some breeds of dog over-represented, therefore genetic-
Labrador Retriever (13% of all mast cell tumour claims)
Staffordshire Bull Terrier (12%)
French Bulldog (7%)
Golden Retriever (7%)
Boxer (5%)
Mutations in the KIT proto-oncogene
20–30% of canine MCT express a mutated form of KIT
Mastinib is a chemotherapeutic that inhibits KIT
MCTs, in the dog, are typically solitary masses
May be within the dermis (cutaneous)
Or subcutaneous
In the cat they are more likely to be visceral
Most common round cell tumour of the feline spleen
MCTs, in the dog, are typically solitary masses
Within the dermis (cutaneous)-
Or subcutaneous
Typically singular on the leg or flank
Nodular, soft mass
Reddening – histamine
Ulceration, pruritus, oedema and swelling of limb – histamine
Rarely, systemic anaphylaxis and/or vomiting due to histamine’s action on the stomach = paraneoplastic syndrome
diagnosis-
Fine needle aspirate (FNA)-
Cytology
Conscious
Cheap
Quick
Can potentially grade but not yet standardised
Biopsy-
Histopathology
GA/ sedation+local
Relatively more expensive
Results take longer to come back
Grading more accurate?
Incisional versus excision biopsy
margins
Stained typically with haematoxylin and eosin
Granules in a well-differentiated neoplasm are easy to see
In cats and poorly differentiated can be hard to see the granules
Giemsa
Toluidine blue
in cats- iological behaviour varies
Most are solitary and benign
Cutaneous or visceral?
Grading scheme
Histological types
Prognostic factors not well defined
grasing mast cell tumours
Histologic grading has been the primary tool for veterinary pathologists to assess the potential biological behaviour of canine MCTs, and it is commonly used for prognostication and therapeutic determination.
In 1984, Patnaik et al., came up with a three-tier grading system that became widly adopted
Grade 1 - low
Grade 2 - intermediate
Grade 3 - high
There has generally been a shift two-tier grading schemes across medicine and veterinary medicine for various cancers
In 2010 the two-tier canine cutaneous MCT grading system by Kiupel, et al., was published
High
Low
According to the Kiupel system (KS), the diagnosis of a high-grade (HG) MCT is characterized by any of the following criteria:
At least 7 mitotic figures in 10 high-power fields (hpf)
At least 3 multinucleated (3 or more nuclei) cells in 10 hpf
At least 3 bizarre nuclei in 10 hpf
Karyomegaly (nuclear diameters of at least 10% of neoplastic cells vary by at least two-fold).
impoetat for predicting prognosis-
Low grade MCTs are composed of relatively monomorphic populations of neoplastic mast cells that have a low nuclear to cytoplasmic ratio, minimal anisokaryosis, single nuclei, often with only one to two nucleoli, and a lowmitotic index(A).
MCTs are classified as high grade if they meet any of the following criteria: seven or more mitotic figures in 10 high power fields (HPF) (B), three or more cells with three or more nuclei in 10 HPF (C), three or more bizarre nuclei in 10 HPF (D), or karyomegaly and anisokaryosis as defined by nuclear diameters that vary by at least two times in at least 10% of neoplastic cells (E). Density of intracytoplasmicgranules, number ofeosinophilsand amount of supporting stroma are variable between tumors and are not features evaluated for grading.
Dogs with low grade MCTs have a significantly longer survival time in comparison to those with high grade MCTs
KIT for predicting the prognosis of mast cells
Mutations in exon 11 of c-kitis an important prognostic indicator in canine mast cell tumours (MCTs).
(A) Dogs with MCTs that have mutations in exon 11 of c-kithave significantly shorter survival times.
Differences in patterns of expression of the KIT protein have also been associated with prognosis
Three distinct immunohistochemical expression patterns of KIT have been described in canine cutaneous MCTs:
(B) peri-membrane labelling =pattern 1
(C) focal perinuclear or stippled cytoplasmic with decreased membrane labelling = pattern 2
(D) diffuse cytoplasmic labelling = pattern 3
MCTs with KIT patterns 2 and 3, which represent aberrant localization of KIT protein, have been associated with decreased survival time and an increased incidence of local recurrence
staging mast cell tumours
As apposed to grading, which is performed by the pathologist, staging is performed by the clinician with the assistance of a pathologist.
Staging is the assessment of whether a tumour has metastasised.
T-N-M classification scheme
T refers to the local tumour
N for regional lymph nodes
M for distant metastasis
For the majority of tumours, a local draining lymph node is typically the first place it will spread to = sentinel
Contrast agent can be used
Imaging and/or FNA for distant metastasis
Liver and spleen
The sensitivity of ultrasound for detecting mast cell infiltration was 43% for the spleen and 0% for the liver. Dogs with positive cytologic evidence of mast cell infiltration to spleen, liver, or both had significantly shorter survival (100 vs. 291 days) than dogs without evidence of mast cell infiltration (P<0.0001). Routine splenic aspiration should be performed regardless of ultrasonographic appearance in dogs with a clinically aggressive mast cell tumour.
Paraneoplastic syndromes
are clinical signs or disorders caused by a neoplasm indirectly and distant from the primary mass or its metastases.
Cachexia
Endocrine tumours- endocrine disease
Reproductive tumours- repro disease an hormone production
Thymomas- myasthenia gravis, polymyositis, various dermatoses
Hypercalcaemia
Myeloma
Amyloidosis
Paraneoplastic syndrom-Cachexia
In cancer cachexia both muscle and fat are lost
Starvation is primarily fat at first
Pathogenesis-
Metabolic catabolism of the neoplasm AND
Production of TNF-a (cachectin), IL-1, IL-6 and prostaglandins-
Anorexia
Lipolysis
Insulin resistance
Paraneoplastic syndromes -Endocrine tumours
See endocrine week for pituitary adenomas, adrenal-dependent Cushing’s and hyperthyroidism
See pancreas dry lab for insulinoma
Neoplasm of islet beta cells
There are other cells within the islets
G-cells -> gastrin
Paraneoplastic syndromes - Reproductive tumours
Sertoli cell tumours
Oestrogen secretion occurs in 20-30% of Sertoli cell tumours
Hyperoestrogenism syndrome
Feminization
Gynecomastia
Bone marrow suppression- Pancytopenia
Squamous metaplasia of the prostate gland
Alopecia
Granulosa cell tumour-
GCTs in the horse are associated with 3 behavioural patterns:
anoestrous; inhibin-producing
nymphomania; continuous or intermittent oestrus; oestrogen-producing
male behaviour; androgen-producing
Testosterone levels are elevated in most cases, but male behaviour is only observed when serum testosterone levels are very high
Paraneoplastic syndromes - Thymomas
Several immune-mediated conditions in humans, dogs, and cats have been associated with thymomas, including
myasthenia gravis
polymyositis
various dermatoses
Exfoliative dermatitis is reported in cats and goats with thymomas
Due to failure of the thymus to remove self-reactive lymphocytes
Paraneoplastic syndromes - Hypercalcaemia
Many neoplasms can result in hypercalcemia
PUPD is most consistent clinical sign
Bradycardia, lethargy, weakness
A functional adenoma of the parathyroid gland will over-produce parathyroid hormone (PTH)
Most common example of ectopic hormone production is anal sac gland carcinoma
Production of parathyroid-like hormone
Like normal PTH, acts to increase calcium in the blood
Others include-
Multiple myeloma
Squamous cell carcinoma in the horse
Metastatic bone tumours
Lymphoma
Paraneoplastic syndromes - Myeloma
Neoplasm of plasma cells
Differentiated B-cell that produces immunoglobulins (antibodies)
Three types of plasma cell tumours:
Extramedullary plasmacytomas-
Solitary or rarely multiple benign tumours arising in soft tissues such as skin and oral cavity
Solitary bone plasmacytomas
Multiple myeloma:
Involves bone marrow of multiple joints
Results in increased immunoglobulins in the blood-
monoclonal gammopathy as all the same as all from one neoplastic plasma cell and its neoplastic daughters
Part of the light chain of the immunoglobulins is seen as Bence-Jones proteins in the urine
Radiography will show osteolysis multifocally
Multiple potential paraneoplastic syndromes-
Hypercalcemia, due to damage to bone
Pancytopenia, due to effacement of bone marrow
Haemorrhage, caused by pancytopenia and secondary platelet dysfunction due to the binding of the paraprotein to platelets
Hyperviscosity syndrome , due to circulating globulins
Renal disease, due to nephrocalcinosis secondary to chronic hypercalcemia, hypoxic damage from hyperviscosity, renal toxicity of light chains and neoplastic cell infiltration into the kidney and/or renal amyloidosis.
Paraneoplastic syndromes - Amyloidosis
Amyloid is a pathogenic proteinaceous substance composed of polypeptides arranged in beta-pleated sheets
Amyloidosis is considered a protein-misfolding disorder in which the proteins biologic function is lost
Types of amyloid:
AL, amyloid light chain; derived from plasma cells; contains immunoglobulin light chains
AA, amyloid-associated; an acute phase protein produced in excess, as a result of chronic antigenic stimulation such as occurs in persistent infections, inflammation, or neoplasia
Aβ Amyloidosis in the cerebral cortex of aged dogs with canine cognitive disorder or human beings with Alzheimer’s disease
Islet Amyloid Polypeptide: amyloid secreting β cells of the pancreatic islets, released with insulin
Pathogenesis:
Genetic-
Kidneys of Abyssinian cats and Shar-Pei dogs
Liver of Siamese cats
Chronic inflammation
Plasma cell tumours
Unknown-
Nasal amyloidosis in the horse
Keratinocytes
85% of epidermis
Ectoderm
function- Skin barrier.
Immune response – phagocytes & cytokine production.
Langerhans cells
(tissue-resident macrophages)
origin- Haematopoietic progenitor cells
function- Immune response
Melanocytes
origin- Neural crests
fuinctionMelanic pigment production, UV protection
Merkel cells
origin- Epidermal stem cells
function- Mechanoreceptos
What is a surgical infection?
Infection that develops up to 30 days after surgical procedure
OR
Up to ONE YEAR if surgical implants placed
skin doesnt form bacteril seal until 24-48 hours after surgery
can be insisional or organ/ space infections
Bacterial sources
Exogenous- e.g on skin
Endogenous- in the animal
Nosocomial - from the vet clinic
Wound Classification – Clean
Elective, non-traumatic procedure
No break in aseptic technique
Infection rates (small animal): 2.5-6%
Do we need to give antibiotics?
Wound classification – Clean - contaminated
Minor break in aseptic technique
Entry into GIT, UG or respiratory tract
Infection rates: 2.5-9.5%
Give antibiotics ?
Wound classification – Contaminated
Traumatic wound more than 6 hours old
Break in aseptic technique
Infection rates: 5.5-28%
Give antibiotics?
Wound classification – Dirty
Traumatic wound over 12hrs old
Infection rate: 18-25%
Give antibiotics?
Biofilm
Structured community of bacterial cells enclosed in a self produced polymeric matrix and adherent to an inert or living surface
Quorum sensing
Matrix is protective
Biofilms grow through a combination of cell division and recruitment
Once developed, biofilm allows bacteria inside to become more resistant to antibiotics
bacteria important in surgical infection
Consider flora of surgical site
Skin:
Dog: Staphs and Streps
Cat: Pasteurella multocida
Respiratory Tract:
Staphs and Streps
Not usually a source of infection
factors present in the GIT that contribute to surgical infection
Oral cavity:
large numbers of aerobic and anaerobic bacteria
Upper GIT
Smaller numbers aerobes and anaerobes
Gram negatives
Small intestine (upper SI) = more and
more anaerobes
Lower GIT (lower SI and LI)
larger numbers of bacteria
Colon:
Far more anaerobes than aerobes
factors present in the Urinary tract that contribute to surgical infection
Sterile – under normal conditions
Staphs and Streps
Coliforms
Usually ascending
Special Considerations for gioving antibiotics after surgery
Dental Procedures
Geriatric Patients
GIT procedures- can make stool lass solid so this should be considered when rupture is ruisk
MRSA/nosocomial infections
MRSA
Methicillin-resistant staph aureus
Human health risk?
Vet ‘antibiogram’ different
Spread by direct contact
Spread limited by basic hygiene and common sense
Any chronic non-healing wound:
Think MRSA
Swab for C+S
Cover wound and barrier nurse or isolate patient
Basic hygiene – wash hands after touching any animal
stop antibiotics as soon as granulation tissue present
Risk factors
Antibiotic overuse
Antibiotic misuse
Patient disease status
Number of procedures
Hospitalisation
swim bladder
The swim bladder is a hollow organ filled with a gas
Main functions
buoyancy
oxygen storage
respiratory functions
communication (hearing and sound production)
In Cyprinidae (carp which includes goldfish)
two chambers, anterior and posterior, linked by a narrow isthmus (ductus communicans)
connected to the oesophagus by a pneumatic duct
*Connected to the oesophagus by a duct in salmonids
*Facilitates buoyancy adjustment by swallowing/expelling air via mouth
name some common diseases of fish
Ich/white spot (Ichthyophthirius multifiliis)
Gas bubble disease
Bacterial kidney disease of salmonids (Renibacterium salmoninarum
Infectious salmon anaemia
Sea lice
Koi herpes virus
Fish tuberculosis (Mycobacterium marinarum) - zoonotic
what are the suggested samples for the histopathology of amphibians
lung or gill
heart
liver
spleen
kidnwy
stomach
small and large intetine
brain
tounge
skeletal muscle
pancreas
gallblader
lymph heart
bine
eye
larynx
peripheral nerve
cloaca
Skin diseases of note in amphibians
Because amphibian skin has such unique structural properties and physiologic functions, skin diseases are among the more common causes of death.
Poison glands
Skin diseases of note
Batrachochytrium dendrobatidis
Chytridiomycosis
Red leg
Aeromonas hydrophila and others
Capillaria xenopodis
Mycobacterium marinarum
zoonotic
iseases of note in reptiles
Risk
Carriers of salmonella
Venomous snakes can still bite!
Oral mucosa with tongue and proximal oesophagus a standard section
Diseases of note
Boid inclusion body disease
Arenavirus
Ranavirus
Ophidiomycosis
tunica fibrosa
external layer of tfish eye
gill anatomy
4 layers of gills on each side
made of two rows of fillaments on each arch
each have many secondary lamilla giving big surface area that may exede that of skin
can be damged easily by pathogens or high C02
responsible for gas exchange, acid base exchange, exchange of nitogenous waste, osmoregulation (ion exchange), immune role
water ust flow in contracurrent
function and location of heart in the fish
Pyramid shaped. Located between liver and gills
Circulates blood throughout the body
function and location of kidney in the fish
Located in the midline running the length of the abdomen beneath the spine, obscured by swim bladde
osmoregulation, excretion of wastes (posterior portion)
manufacture of RBC & immune function (anterior portion ).
Smooth uniform surface-wine/brown/black in colour
function and location of liver in the fish
Largest organ - anterior abdomen around stomach
Assists in digestion, fat storage, processing toxins (nitrogen waste excretion)
function and location of spleen in the fish
Dark red, located caudally in abdomen
Blood cell formation, immune response, blood filtration
function and location of pancreas in the fish
Distributed throughout fat around pyloric caecae
Secretes digestive enzymes & hormones.
reproductive system of fish
Located in dorsal abdomen below the swim bladder. In pair connected to the vent (anal/urinary pore), but in salmonids oviduct not fully connected, eggs are released in the peritoneal cavity.
in salmonids eggs released into peritoneal caity rather than directly to vent
muscle of fish
W-shaped myotome
muscles are layered not stiated
have red muscle in lateral line and base of finsfor swiming
white muscle in body
lateral line system
lso called lateralis system, a system of tactile sense organs, unique to aquatic vertebrates from cyclostome fishes (lampreys and hagfish) to amphibians, that serves to detect movements and pressure changes in the surrounding water. It is made up of a series of mechanoreceptors called neuromasts (lateral line organs) arranged in an interconnected network along the head and body. This network is typically arranged in rows; however, neuromasts may also be organized singly. At its simplest, rows of neuromasts appear on the surface of the skin; however, for most fishes, they lie embedded in the floor of mucus-filled structures called lateral line canals. These canals are placed just underneath the skin, and only the receptor portion of each neuromast extends into the canal. In amphibians the lateral line system occurs only in larval forms and in adult forms that are completely aquatic.
osmoregulation of fish
25 – 50% total energy output used for osmoregulationInvolves kidney, gut & gillsFluid & salt balance
Notifiable fish diseases
Epizootic haematopoietic necrosis- (EHN)Declared free
Gyrodactylus salaris (GS)-Declared free
Infectious haematopoietic necrosis (IHN)- Declared free
Infectious salmon anaemia (ISA)- Declared free
Koi herpesvirus disease (KHV)- Undetermined
Spring viraemia of carp (SVC) -Declared free
Viral haemorrhagic septicaemia (VHS)-Declared free
Bacterial kidney disease (BKD)-Not recognised as free. Disease in control nationally.
cinical signs of parasites in fish
FlashingRapid opercular movementFlared gillsThickening of gill epithelium on microscopic examinationDarkening in fryGrey patches*Increased mortalities
Sea lice
Skin damage, stress and general weakness
*Osmoregulatory failure
*Irritation – pain?
*Decreased appetite
*↑ susceptibility to other diseases
*↑ susceptibility to damage/stress during handling
Amoebic gill disease (AGD) (SW
caused by the protozoan Neoparamoebaperurans
*Wrasse, Lumpfish and Salmon particularly susceptible
*Clinical disease most common between 12-20°C
*Can survive on gills of dead fish
*Can cause high mortalities (hatcheries and pens)
*Proliferation of lamellar epithelium and increased mucus production
Costia
*Flagellated protozoa
*Parasite may be free swimming or attached to fish cells.
*Free swimming shows erratic rapid movement easily seen under low power (x10),
*Observation of flagellae under higher power confirms identification.
*Attached stages can be seen round edges of secondary lamellae.
*Treatment: Formalin baths
Chilodonella
*Ciliated parasite
*Large parasite (easily seen under low power), free swimming, with slow, undulating motion, appears to graze over edge of gills.
*Increases mucus, hypoxia
*Treatment: Formalin baths
Trichodina
*Ciliated parasite
*Large (easily seen under low power), free swimming, with circular motion, using numerous cilia round edge (look like flying saucers).
*Treatment: Formalin bath
White spot (ich)
*Icthyophthirius multifilis
*Ciliated
*Several life stages occur but identification is usually on large mature stage embedded in fish skin. Horse shoe shaped nucleus is easily identifiable feature.
*Skin & gill irritation, respiratory distress.
Micro skin lesionsStress
*Prevention/management: Good tank hygiene, disinfection of equipment.
*Treatment: Formalin bath
Non motile fish parasites
Capriniana sp. (Tricophyra)
*Scyphidia
*Fixed in place
*Feed on organic matter in water
Proliferative kidney disease
Tetracapsuloides bryosalmonaePrimarily occurs during summer
Gross lesions: Darkened body color, exophthalmos, pale gills, abdominal swelling, ascites, splenomegaly, and enlargement of kidney
Management: Clean environment, reduce stress, reduce temperature
Furunculosis-Aeromonas salmonicida(SW, FW)
*Acute septicaemia: persistent increased mortalities
*Chronic: furuncles, skin lesions
*Outbreaks generally >16°C
*Horizontal transmission: water column, direct fish-to-fish, vectors
CLINICAL SIGNS:
-Sudden death (acute infections)
-Lethargic swimming, surface-swimming (fish with exophthalmia)
-Loss of appetite, respiratory distress, fish jumping from water
-Haemorrhages in internal organs, enlarged spleen and focal liver necrosis, congested GIT
PREVENTION & CONTROLVaccinationAntibiotherapy*Biosecurity
Enteric redmouth disease (ERM) –Yersinia ruckeri (SW, FW
*Acute septicaemia
*High survival in environment (months)
*Horizontal transmission: fish-to-fish
*Once in the system, difficult to clear
Carrier status possible
CLINICAL
SIGNS:Unspecific
*Increased mortalities
*Fish swimming near surface or tank-edges
*Dark colour
*Poor feeding response
CONTROL:
*Vaccination, Antibiotherapy, biosecurity
Tenacibaculum sp
Salmon, Wrasse and lumpfish (SW)
T. maritimum, T. dicentrarchi, T. finnmarkense
External lesions, gill/fin rot, systemic infection
Predisposing factors: Water temperature, poor water quality, skin damage, jellyfish?
BKD (Renibacterium salmoninarum
Notifiable
Clinical signs:*Dark coloration, exophthalmos, pale gills, abdominal distension, or hemorrhages at the vent or base of the fins.
*Kidney- nodular masses
Control: Appropriate antibiotic / appropriate biosecurity. If outbreak is observed, follow eradication plan.
BKD (Renibacterium salmoninarum
*Classical vibriosis
*23 serotypes (only 01, 02a/ß and 03 pathogenic)
Serotype 01
*Also infects salmonids
*Serotype most regularly isolated from cleaner fish
Serotype 02a/ß
*Often isolated in other marine species
Signs:High mortalities, lethargy, loss of appetiteSuperficial congestion and haemorrhage
*Systemic infections: similar to furunculosis May be present in the gut of healthy fish and be stress activated
Winter ulcer - Moritella viscosa
Observed during colder months
Affects osmoregulation
Might heal, but leaves scarring tissue and melanisation
Wild wrasse (UK), lumpfish in Ireland, Iceland
Research indicates differences between salmon and lumpfish isolates in Iceland
Salmonid rickettsial septicaemia (SRS) - Psicirickettsia salmonis
Significant pathogen of Atlantic salmon, has also been observed in Rainbow trout & Lumpfish
Facultative intracellular bacteria
Clinical signs:Lethargy, haemorrhagic skin lesions, ascites, discolouration of heart (fibrinous epicarditis) and liver, pale gills, swollen kidney, granulomas in liver or spleen.Petechial haemorrhaging of GIT and swim bladde
Pasteurella sp. (Salmon & Lumpfish)
Pasteurella skyensis affects Salmon SW
*Two serotypes, O2 in Scotland
*Lethargy, skin darkening
*Anaemia, petechia in internal organs and muscle
Pasteurella sp.in Lumpfish
*Head ulcers, white spots on skin, bleeding gills, tail rot
*Granulomas, white nodules on organs, swollen spleen, ascite
Pseudomonas anguilliseptica(CF
Affects Lumpfish
External signs
*Redness in lower jaw, cheeks, around ventral part of body and pectoral fins, darkening of last third of body flanks.
Internal signs
*Enlarged kidney and liver, ascites
OOMYCETES-SAPROLEGNIA
fungus in fish
Economically significant pathogen to FW aquaculture around the world
Characterised by white/grey patches of filamentous hyphae
Saprolegnia diclina- infects eggs
Saprolegnia parasitica- infects fish
Represents major source of losses in FW salmonid aquaculture
MANAGING THE DISEASE
Bath treatments – early treatmentGood tank hygiene and water quality
Minimise stress
Remove mortalities
Exophiala sp
fungus in fish
Affects lumpfish: Black lesions observed in all tissues (heart, gills, caecae, liver, kidney, spleen, muscle, skin.)
Infectious Pancreatic Necrosis (IPN)
IPN is a disease of stressed salmonids!
*Clinical disease generally occurs when fish are most vulnerableor subjected to heaviest stresslevels. Freshwater and marine stages (most vulnerable after hatching).
*In fry IPN generally occurs within 3-4 weeks of first feeding. Onset of disease can be explosive with up to 90% losses.
*Mortality level is often related to stocking density and environmental conditions, survivors become carriers (faeces, gonad fluids, mucus, urine).
External signs- Loss of appetite- Sluggishness - Spiral swimming- Protruding vent- Trailing cast- Popeye- Swollen belly- Change in pigmentation
Internal signs- Pale liver (consistent finding in fry, liver looks like condensed milk)- Ascites- Visceral fat petechiae- Empty gut with whitish or yellow exudate
Salmon gill poxvirus (FW & SW)
Detected in Norway, Scotland, Ireland, FaroesSuspect Pox Virus damages epithelium and paves the way for other pathogens
*Compromises mucosal defense of the gills.
*Clinical signs -described mainly for salmon fry: loss of appetite, lethargy and crowding in the bottom of the tank (respiratory distress).
*On gross examination the gills appear pale and the filaments swollen.
Pancreas Disease (PD)/Sleeping disease –Salmon Alphavirus
Virus infection targets:
*(Systemic – general weakness/lethargy)
*Pancreas = impaired food digestion/absorption
*Heart = increased susceptibility to stress/handling
*Skeletal muscle = impaired swimming
Clinical appearance (signs observed, mortality level etc) can be quite variable. Typical signs include:
-Lethargy, altered appetite, fish “hanging about”, fish spiralling to the bottom of the pen, thin snake-like fish, yellow faecal casts, sudden death at handling, poor FCR
PREVENTION= Vaccination / fallowing / SD / good condition fish
MONITORING= serology/PCR
MANAGING THE DISEASE
Disease stages:Viraemia (early stages of the infection)
careful management! Avoid stressAntibodies (late stages – from 3 weeks post-infection)Samples to assess level of damage (CPK, histology)Remove morts
Cardiomyopathy syndrome in Salmon (CMS) – Piscine Myocarditis virus (Totirividae)
Virus infection targets:
Heart = increased susceptibility to stress/handling.Liver (probably secondary changes to heart damage.
*Signs: Ascites/oedema due to heart failure.Fibrin around heart and/or liver.Enlarged heart.
*Usually affects large fish close to harvest – only noticed when fish die at harvest crowd.
*Corkwing and ballan wrasse on 2 sites in Ireland
*Wrasse have to be considered potential vectors
*In 2017, increased incidence in smaller fish, with very high mortality in some cases.
Heart and Skeletal Muscle Inflammation (HSMI) – Piscine Reovirus
This virus is found in almost all farmed salmon, however not all salmon will develop this disease!->
THIS IS AN IMPORTANT REMINDER THAT THE PRESENCE OF A PATHOGEN DOES NOT ALWAYS MEAN DISEASE WILL OCCUR!!!
Virus infection targets:
*Heart = increased susceptibility to stress/handling
*Skeletal muscle = impaired swimming
*Red blood cells (?associated with blood cell disorders?)
*(Systemic – general weakness/lethargy?)
Infectious Salmon Anaemia (ISA)
Contagious viral disease
*Causes severe haemorrhaging & anaemia
*Can lead to significant mortalities
*Notifiable disease
Infectious haematopoietic necrosis (IHN) & Viral haemorrhagic septicaemia (VHS)
Contagious viral diseases, mainly FW but can be observed in SW
Notifiable diseases, outbreaks require compulsory slaughter
UK approved zone, disease freeBoth are caused by Novirhabdovirus
Vertical & horizontal transmission, affects all ages, several types of salmonids and other species too.
IHN Signs are: Lethargy, anaemia (pale gills and internal organs), exophthalmia, haemorrhagic fins, ascites.
VHS signs are: Exophthalmia, ascites, dark skin, haemorrhages in internal organs and muscle, pale gills.
Control: Biosecurity, use of disease free ova. Screening of fish prior reception
Flavivirus (CLuV or CLuFV)
Repeatedly detected in lumpfish in Norway and the UK
High mortality has been attributed to the infection
Histology characterized by liver pathology
Research ongoing
Lumpfish Coronavirus (CLuCV), Lumpfish Totivirus(CLuTV
CLuTV, anecdotal experience:
Detected in alevins and juveniles, mainly during presence of intestinal Vibriosis, associated to “diarrhoea” (co-infection?)*Not detected any more from young adults
CLuCV, anecdotal experience:
*Detected in adults, no clear mortalities associated to it yet.
Both viruses still under research
causes of non infectious fish disease
Water quality-
Environmental gill disease
NephrocalcinosisGas bubble disease
Supersaturation
Physical/environmental-
Algae/JellyfishPredation
UV,
electrocution
Behavioural-
Tail biting (stress, light, lower stocking densities?)
Mitigated by environmental enrichment?
Air gulping
Management related-
High susceptible to stress, handling Welfare important
Cataracts -
Likely nutrition related
infectious
Linked to fast growth/high temperatures?
Light wavelength- green light 520nm?
Nutritional -
Deficiencies
Fat rancidity
Mycotoxins
Deformities-
Sucker deformities common problem in lumpfish
Skeletal deformities underdiagnosed?
Egg incubation temperatures, nutrition, …
Haemorrhagic smolt syndrom
Skin lesions:
*Open doors to other infections
*General weakness
*Decreased appetite
*Irritation – pain?
*Osmoregulatory failure
*PREVENTION = Adequate/careful handling
*MONITORING= check fish condition (morts, divers, sub-sampling)
*MANAGING THE DISEASE
*Careful handling
*Antibiotics needed?
*FW/disinfectant bath
Non-infectious gill damage
Physical/environmental
Algae/Jellyfish: Plankton
Reduce O2 content in water
Physical damage
Toxic damage
Supersaturation
Vectors for bacteria
Sublethal exposure to harmful plankton is stressful & increases disease susceptibility
Harmful plankton can affect wild fish, however farmed fish at significantly greater risk because they are unable to escape in the face of a bloom.
Strawberry Disease (SD)also known as Warmwater strawberry disease (WWSD) or Summer Strawberr
Clinical findings:* Red marks on flanks and beneath fish* Lesions only skin deep* No other gross effects* No mortalities* If fish left alone, lesions resolve in a few weeks
Antibiotic successful
Cause unknown (probably bacterial)
Can be prevented by use of high levels of vitamin C and glucans
Histopathology:* Dermatitis involving the epidermis* Dermis and sub-dermal tissues usually unaffected* Epithelial hyperplasia
Puffy Skin Disease (PSD)
Severe dermatitis affecting Rainbow trout:
Excess mucus on flanks of fish – no parasitesOedema of skin*White or grey skin patches +/- petechial haemorrhages → raised, reddened “blister” lesions and scale loss.
Associated with a very low mortality, but potentially significant economic losses for affected farms due to downgrades, the need for culling and increased production costs.
Usually affects 1kg+ triploid rainbow trout, however, could affect smaller (400g) too.
Similarities between PSD, RMS and SD, but they can be differentiated based on their epidemiological and clinical characteristics.
Not yet seen in brown trout or other salmonids
Seen year-round, temperatures between 5.4 and 16.9 °C but prevalence and severity greatest during late summer and autumn, declining over winter
Badger Tuberculosis
Bovine tuberculosis (bTB)
Mycobacterium bovis
Gram positive, acid-fast
Slow growing, long incubation period
Shed through urine, faeces, sputum and discharge from bite-wounds
Badgers are highly susceptible to M. bovis infection
Often latent, subclinical infections (no visible lesions)
Stressors: concurrent disease, pregnancy, old age
Primarily respiratory disease progression to systemic dissemination
testing-
Culture pooled tissue (Lowenstein-Jensen, Stonebrink or Middlebook 7H11 culture mediums)
Gold standard (6-22 weeks)
Post-mortem examination
Ziehl-Neelsen stain
Cytology or histology sections
PCR – APHA (PM tissue samples)
gross leasions-
Experimental infection (left)
Respiratory inoculation
Mimics severe disease in naturally-infected badgers (right)
Multifocal to coalescing 1-2 mm diameter discrete pale yellow to white tubercles, to extensive miliary lesions
Lobar caseation and consolidation
Lymphadenomegaly
Oedema
Multifocal to coalescing pale yellow to white
Systemic dissemination ->renal disease
Radial granulomatous nephritis
Histologic features differ slightly from bTB in other species
No encapsulation, abscessation, or layered organised granulomas with multinucleated giant cells
Epithelioid cells (E) are surrounded by fibrosis (F) with lymphocytes, plasma cells, macrophages and neutrophils +/- central necrosis (N)
Granulomas within a lymph node
Similar histologic pattern
Centre of epithelioid cells surrounded by fibrosis and inflammation
Badger are implicated in the transmission to cattle
Small ruminants are susceptible (goats and sheep)
Zoonotic risk - human tuberculosis
Red fox and Lungworm (Angiostrongylus vasorum)
Implicated in the transmission of lungworm to dogs
Often subclinical / asymptomatic
Canine lungworm - Angiostrongyliasis
Angiostrongylus vasorum
AKA French heartworm
L3 (ingested infectious stage)
Adults found in lungs & heart
Right ventricle / pulmonary artery
Eggs in lung capillaries
L1 coughed up
testing-
A. vasorum SNAP test - ELISA
Blood sample
Good sensitivity and specificity
Rapid and reliable
Ante-mortem
Faecal smear
Distinctive kinked tail of L3 larvae
Baermann faecal flotation
Detection of L3 larvae
Eggs aren’t shed so we can’t use a worm egg count
Time consuming
Low sensitivity due to intermittent shedding
Pool faeces over multiple days
gross leasions-
Adults in right ventricle and pulmonary artery
Pulmonary hypertension
Right sided heart failure (cor pulmonale)
Caudodorsal firm, bulging nodules
Consolidation
histology-
Presence of eggs and larvae within airways
Granulomatous inflammation (macrophages and multinucleated giant cells)
Adults in vessels
Loss of alveolar structure
Fibrosis
Source of infection for dogs
Greater chance of transmission in urban environments
Slugs / snails are required for the life cycle - wet environments
Can induce haemostatic dysfunction in infected dogs
Mucosal bleeding
Scleral bleeding
Red squirrel and Squirrel pox virus
Squirrel pox virus - poxvirus
Poxviruses are resistant and survive outside the host
Occurs in England in areas co-inhabited with grey squirrels
Asymptomatic in grey squirrels
Transmission via body fluids and shared parasites
Rapid loss of body condition and subsequent death
ELISA (antibodies)
Post mortem examination
Histopathology
PCR
Electron microscopy
Raised crusting and erythematous dermatitis
Oral, periocular, vulvar folds, nail bed
Poor body condition
Epidermal ulceration
Ballooning degeneration of the intact epidermis
Mixed inflammatory dermatitis
Intracytoplasmic eosinophilic viral inclusion bodies within keratinocytes
European rabbit and Rabbit haemorrhagic disease virus (RHDV)
RHDV2 - Type 2 subtype is now most common
Calicivirus - Lagovirus
Shed in secretions - direct contact and indirect through fomites / ectoparasites
High mortality in domestic and wild rabbits
Death 48-72h following infection
Peracute: no clinical signs, sudden death
Acute: anorexia, ataxia, abnormal behaviour, conjunctival congestion
Subacute: similar clinical signs, not as fatal
testing-
PCR (RHDV1 + RHDV2)
Post mortem
Histopathology
Immunohistochemistry
gross lesions-
Sudden death
Splenomegaly
Widespread haemorrhages
DIC
histology-
Multisystemic haemorrhages (DIC)
Acute splenic necrosis
Portal to diffuse hepatic necrosis
Disassociation of hepatic cords
Electron microscopy (research)
Eurasian otter and red fox and Highly pathogenic avian influenza
Avian influenza virus
Predominantly affects poultry and waterfowl
Rare spill-over detected in wild mammals
UK detection
Foxes
European Otters
Grey seals
testing-
PCR detection
Immunohistochemistry
Detection of virus antigen
Reddish brown = positive
Describe the groups and tools involved in UK small animal disease surveillance
AMR and anthelmintic resistance
Zoonotic disease detection and control
Statutory reporting of notifiable and reportable diseases
Food safety – residues and contamination
Detection of threats to international trade
Reporting adverse reactions to Veterinary Medicines Directorate (VMD)
Gathering evidence to inform field studies and targeted surveillance
Helping build valuable archive of samples
APHA
Veterinary Medicines Directorate (VMD)
SAVSNET
VetCompass
Cats Protection
Dogs Trust
RSPCA
SSPCA
City of London, Heathrow Animal Reception Centre
BSAVA
ESCCAP UK & Ireland
DEFRA Trade Team
Veterinary Medicines Directorate (VMD)
Demonstrate the groups and tools involved in UK small animal disease surveillance using the example of an acute vomiting outbreak in dogs, how a surveillance network can inform probable cause and control
January 2020: Vet in Liverpool raises concerns of increased cases of acute, severe vomiting in dogs (~40 cases) – approaches SAVSNET
SAVSNET: data on main presenting complaints and free-text mining from electronic health records 2014-2020 – significant rise in cases between December 2020 to March 2020.
Parallel significant rise in the use of maropitant (anti-vomiting drug)
Spatiotemporal mapping showed clustering in NW and SW England and Edinburgh
February – March 2020: Rapid case-control questionnaire survey of 1200 owner-reported cases.
February 2020: Looked back at diagnostic data Jan 2017 – Feb 2020: PCR of enteric diseases including Giardia, Clostridia, Parvovirus, Canine Enteric Coronavirus (CeCoV)
February – March 2020: Rapid case-control questionnaire survey of 1200 owner-reported cases in 4.5 weeks.
Male dogs and dogs in contact with other vomiting dogs significant
No obvious association with SARS-CoV-2
February 2020: Looked back at diagnostic data Jan 2017 – Feb 2020: PCR of enteric diseases including Giardia, Clostridia, Parvovirus, Canine Enteric Coronavirus (CeCoV)
Why do a PME on small animals?
Owner wants confirmation that it was not their fault that their pet died
*Owner wants to know why their pet died
*Owner wants to know if it is somebody else’s fault e.g. the vet’s that their pet died
*Owner wants to know if the neighbourpoisoned their pet.
*Vet wantsto know what went wrong/ what was missed/ what could they do different
*Welfare investigations e.g. RSPCA or Police
*Grouped kennel/ breeding setting
Why do a PME on large animals?
Owner wants to know what they can do to prevent cohort animals being sick/ dying
*Owner wants to know why their individual animal died
*Owner wants to know why their treatment attempts didn’t work
*Owner wants confirmation of cause of death for insurance purposes
*Welfare investigations e.g. RSPCA, Police, Trading Standards
Whenever you consider a notifiable disease likely, it is illegal to
carry out a PM/ further investigationsWhat to do instead? Call the Defra Rural Services helpline (APHA)
HSE Approved List of Biological agents based on categorization by ACDP Hazard Group definitions:
Group 1 Unlikely to cause human disease.
* Group 2 Can cause human disease and may be a hazard to employees; it is unlikely to spread to the
community and there is usually effective prophylaxis or treatment available.
* Group 3 Can cause severe human disease and may be a serious hazard to employees; it may spread
to the community, but there is usually effective prophylaxis or treatment available.
* Group 4 Causes severe human disease and is a serious hazard to employees; it is likely to spread to
the community and there is usually no effective prophylaxis or treatment available
ACDP cat 4: currently unlikely to encounter in the UK in routine PMEs e.g. Ebola,
Hendra Virus. Though beware old-world primates (esp macaques) potential carriers
of cat 4 Herpesvirus B!
ACDP cat 2: various common pathogens (incl Leptospira spp, Listeria spp,
Pasteurella spp etc) that can result in significant disease in individuals and one of
the reasons why to wear appropriate PPE when carrying out PMEs. Includes also
pathogens like Chlamydia abortus or Toxoplasma gondii – higher risk if pregnant or
immunocompromised!
ACDP cat 3: main zoonotic concern in the UK especially if pathogen can aerolise.
Risk assessment of potential presence needs to be done prior to considering if
carrying out any PME
Zoonotic risks during PME of farm animals in the UK
ACDP3 and notifiable/ reportable zoonotic diseases potentially found in UK:
* Bacillus anthracis – consider in all sudden death animals esp cattle (last case in the UK in 2015)
and in cases of throat swelling in pigs
* Mycobacterium bovis – TB (concerns include alpacas)
* (Brucellosis – UK free of Brucella abortus and melitensis but some cases of B canis now in dogs
and brucellosis in marine mammals)
* BSE – all ‘fallen stock cattle’ over 48 months of age must have their brainstem tested for BSE
* (Highly Pathogenic Avian Influenza – poorly defined zoonotic risk and changing)
(some) ACDP3 pathogens present in the UK
* Q-fever (Coxiella melitensis) - esp abortions of ruminants esp goats
* Chlamydia psittaci – birds esp psittacines and pigeons
* Louping Ill (tick-borne disease) - esp sheep and grouse
Types of samples to take during PME
Histopathology / (Cytology)
Bacteriology/ Microbiology
Virology
Parasitology
Biochemistry / Toxicology
Histopathology samples in a pm
Where do we collect the sample into?
What is the “perfect” sample for histopathology?
Ratio sample size to fixative volume
Where do we collect the sample into?
▪ 10% neutral buffered formalin (CAVE: fumes have carcinogenic potential)
What is the “perfect” sample for histopathology?
▪ <1cm thick but wide and long enough to be representative of lesion
(fixation speed approx. 1mm per hour)
▪ From the edge of affected to unaffected tissue
▪ Handle carefully, don’t squash, avoid contamination etc
Ratio sample size to fixative volume
▪ >10 times the volume of formalin compared to tissue volume
Bacteriology sampling - culturein pm
Requirement of live bacteria for culture
Avoid contamination
Swab (charcoal medium), taken in a sterile manner (e.g. heat searing of
surface), or large section of tissue (into sterile container)
Preferred location of sample: edge ↔ centre of lesion
▪ Previous treatment with antibiotics
▪ Abscess/ granuloma
Aerobic (routine and/ or selective) ↔ anaerobic
Keep sample cool
Bacteriology – alternatives for bacteria growing poorly in
routine culture media
Selective media required
Anaerobic culture with adapted sample technique
Special staining/ labelling of impression smears (or histopathological sections)
PCR
Histopathology +/- special stains +/- IHC
Toxin detection rather than bacterial detection
Virology samples for pm
PCR
▪ Piece of affected tissue or swab
Viral culture/ isolation
▪ Viruses very fragile, often dead in PM samples
▪ Very expensive
Histopathology +/- Inclusion Bodies +/- IHC
((paired) serology
Parasitology samples for pm
Helminths
* Worm egg count e.g. McMaster’s
* Total worm count: Washing of contents of abomasum and small intestine with subsequent sieving and
microscopic assessment
* Visualise grossly esp fluke, tapeworm, Haemonchus spp, lungworm
Ectoparasites
* Skin scrapings
* Histopathology
* Visualise grossly e.g. lice
Protozoa
* PCR e.g. Toxoplasma, Neospora
* Histopathology e.g. Histomonas spp
* Scrapings/ Worm egg counts/ Flotation/ Smear +/- stain e.g. Coccidia, Giardia, Cryptosporidia spp
Blood-borne parasites
* PME not diagnostic test of choice
* PCR
Biochemistry/ Toxicology samples in pm
post mortem blood? What makes sense testing?
* Haematology: useless
* Biochemistry: useless; apart from ZST in neonatal animals if only minor
haemolysis of sample
* Serology: sometimes possible if test not very sensitive to haemolysis +/- only
minor haemolysis
- Urine
- Glucose
- Other parameters unreliable – sloughing of mucosa
Tissue analysis: liver ↔ kidney
▪ Suspect acute toxicities: predominately testing of kidney tissue as toxin is circulating in
blood stream (excretion via kidneys)
▪ Mineral status/ chronic phase of toxicity: test storage organ, e.g. liver for copper,
selenium, cobalt
Keep tissue frozen (minimum tissue size: > 10g !) – can be processed later
Eye fluid analysis (collect asap after death; <48 h):
▪ Vitreous/ aqueous humour esp Mg, Urea, Ca, BHB, nitrate/ nitrite
* Use of ocular fluids to aid postmortem diagnosis in cattle and sheep
Toxicology for plant poisoning?
Clinical history as guidance – look at the
field/ environment
Look for plant fragments in the
gastrointestinal tract
* E.g. yew, rhododendron, pieris, acorns
No testing available for many “fast acting”
plant toxicities
Histopathology for some “slower” plant
toxicities to provide evidence of toxic effect
rather than plant aetiology e.g. ragwort (liver
samples to take in suspected poisoning cases
Collect the following samples on PM:
▪ Stomach + intestinal contents
▪ Liver
▪ Kidney
▪ PM blood
▪ Urine
▪ Fat
▪ Brain (if suspect organophosphate poisoning)
Freeze unless there is evidence of involvement of a specific toxin that can be tested for.
If suspicion of poisoning persists after histopathology, discuss possibilities/ options with
owner.
You will need to provide the testing laboratory with a list of what you want to test for (and
find out if available): limiting additional factors include costs, lack of “normal” background
reference range
serous atrophy of fat
strong indicator of imaciation
rules out sudden death
Grouping of causes of sudden death
InfectiousMetabolic/ feed-relatedToxic Traumatic, accidental, miscellaneous
Clostridial diseases
Pigs: especially Clostridium perfringens type C –Necrotising enteritis Sheep: especially Clostridium perfringens type D –Pulpy kidney disease Goats: especially Clostridium perfringens type D –Necrotising enteritis Cattle: especially Clostridium chauvoei–Blackleg Other Clostridia sppto consider: Cl. novyi(Black disease), Cl. perfringens type B (lamb dysentery), Cl. tetani, Cl. botulinum, Cl. difficile (Cl. septicum, Cl. sordelli, Cl. haemolyticum, Cl. perfringenstype A)
PM findings ‘pulpy kidney disease’?
Pericardial fibrinous effusionConing of the cerebellum Advanced autolysis kidneys Widespread haemorrhages (e.g. kidney, heart) Glucosuria Confirmation of diagnosis? Toxin ELISA on ileal content (Histopathology brain)
Oedema disease pig
Usually shortly post-weaningIntestinal infection with E.colistrains that produce Shiga/ Verotoxins(STEC/ VTEC) with subsequent toxaemiaPM findings: from none to oedema especially subcutaneously (face and eyelids), the greater curvature of the stomach and the mesocolon Diagnosis?Isolation of specific serotypes of E.coli and/ or toxin gene PCR in intestinal contents *Histopathology brain
Diagnosis of nematodes on PME
Worm egg count on large intestinal contents –limitations? *WEC cannot distinguish between trichostrongyle-type eggs (strongyle eggs) e.g. Haemonchus, Teladorsagia, Trichostrongylussppetc
*Disease during prepatencyperiod especially NematodirusbattusGrossly visible HaemonchussppTotal worm count –washing abomasum/ C3 and small intestine –sieving contents through a defined sieve size-microscopically count and identify present nematodes
Metabolic/ feed-related causes of sudden death in farmed animals
Hypomagnesaemia (staggers) (Hypocalcaemia)Vit E / SeCCN / PEMRuminal acidosisBloat‘Redgut’ Stomach ulcers Caudal Vena cava syndrome
Caudal vena cava syndrome cattle
Possible clinical presentation?
*Sudden death with a large pool of blood around nose/ mouth (DD: anthrax) What does the arrow point to?
▪Thrombus in a pulmonary vessel How did it get there?
▪Thromboembolism e.g.from the caudal vena cavaMost likely pathogenesis?
▪(Subacute/ subclinical) ruminal acidosis → rumenitis → liver abscesses → caudal vena cava abscess/ thrombus → thromboembolism to smaller lung vasculature → vascular erosion and haemorrhage
pm Diagnosis of suspected metabolic disease
Hypomagnesaemia: ocular fluid (vitreous humour)
Hypocalcaemia: ocular fluid (aqueous humour)
Vit. E/ Se deficiency-
*White muscle disease (gross and/ or histo): multifocal muscle necrosis
*Mulberry heart disease: pericardial effusion, stripy haemorrhages heart (angiopathy)
*Massive hepatic necrosis
*Diagnosis: histopathology, liver Se, cohort blood biochemistry
CCN / PEM-
*Mostly associated with Vit B1 def/ Thiamine
*Autofluorescence brain under UV light (some)
*Histopathology brain
*Differential diagnoses: sulphur-toxicity, lead toxicity, water deprivation/ salt poisoning
Examples of toxic causes of sudden death in farmed animals
Copper poisoning- *PM findings: anaemia, jaundice (pre-hepatic icterus)
*Diagnosis: tissue biochemistry –KIDNEY!
Lead poisoning- Diagnosis: tissue biochemistry –kidney Iatrogenic -E.g. Nitroxynil
BEWARE! Food Safety Incidents
Phylogenesis
the evolutionary development and diversification of a species or group of organisms, or of a particular feature of an organism
Ontogenesis
the development of an individual organism or anatomical or behavioural feature from the earliest stage to maturity
gyri
raised ridges of brain
sulci
ridges of brain
crainial nerves connected to cerebelum
1
crainial nerves connected to diencephalon
2
crainial nerves connected to mesencephalon
3 and 4
3 and 4
5
crainial nerves connected to medulla obongata
6,7,8,9,10,11,12
glial cells
a type of cell that provides physical and chemical support to neurons and maintain their environment. Located in the central nervous system and peripheral nervous system, glial cells are sometimes called the “glue” of the nervous system,
protection of the brain
Blood brain barrier integral to protect from infection and toxins
Glial cells are effectively the nervous system of the brain
Phagocytosis
Neurones
long-lived post-mitotic cells
Lipofuscin- Age-related and incidental
Overproduction/acceleration associated with some diseases (lipofuscinosis)
long-lived post-mitotic cells
Lipofuscin- Age-related and incidental
Overproduction/acceleration associated with some diseases (lipofuscinosis)
Neurones are most susceptible to injury
High energy requirement
No internal stores of glucose
Limited ability to cope with accumulation of intracellular calcium- important factor in repairable damage and non repairable
Are terminally differentiated in the adult – no repair
Neuronal injury and death looks just like injury in other cells with some key differences:
Chromatolysis
Shrunken
RED IS DEAD
However, overhandling fresh brain at post mortem causes this artefact
Edges only?
Neurones can die via necrosis (oncosis) and apoptosis
Glial cells will proliferate and there will be increased infiltrating leukocytes starting at the vessels
None of the above are particularly specific for cause
Just like in any other part of the body, acute inflammation is associated with vascular changes that can result in oedema
In the brain this has dire consequences due to being encased in the skull
Flattened gyri
Herniation- cerebellum herniates out of skull resulting in coning
Vascular occlusion
Wallerian degeneration
Response of axons and myelin to injury-
Swollen axon
Degeneration and loss of myelin sheath
Macrophage infiltration
Proximal and distal axon will also degenerate
Degeneration of neuronal cell body will also occur
Again not pathognomic for cause but frequently seen with anything that causes spinal cord compression
-disc disease
-cervical myelopathy
Degenerative diseases of the brain
Aged dogs and cats develop deficiencies in learning and memory-
In dogs is referred to as canine cognitive dysfunction- May be analogous to Alzheimer’s : Senile plaques and cerebrovascular amyloidosis (a blob of pink material assosiated with inflamatory proceses)
See DMJ’s lecture
Also, a syndrome characterised by severe and acute but typically (partially) transient defect of the central vestibular system (vestibular syndrome) is seen in dogs -Idiopathic
Anomalous/congenital diseases of the brain
Myasthenia gravis-
Can be congenital or acquired
Congenital form-
Mutation in one of several genes associated with normal production or function of acetylcholine
Acetylcholine stimulates muscle contraction
And is main neurotransmitter in parasympathetic system
megaoesophagus can occur- apears as regurgitation
Acquired form-
Due to autoantibodies against the acetylcholine receptor- Thymic mass
Tensilon/edrophonium test-
Anti-cholinesterase
Metabolic and nutritional of the cns
The brain is reliant on glucose
Diseases the cause hypoglycaemia will result clinically in collapse, coma and/or seizures-
Diabetes mellitus
Insulinoma
Very metabolically active and post-mitotic
Heavily reliant on anti-oxidants
Thiamine-
Deficiency in cattle results in polioencephalomalacia (PEM) also known as cerebrocortical necrosis (CCN)
Typically due to sudden shift to concentrates or sulphur contamination of food or water
Wandering, circling, cortical blindness, incoordination, head pressing, recumbency, nystagmus, and seizure activity
Gross
swelling of the brain
fluorescence
The brain is also reliant on electrolytes
Dairy cows may suffer events of hypocalcaemia and hypomagnesemia, commonly known as milk fever and tetany respectively.
Milk fever is characterized by hypocalcaemia at parturition as a consequence of a sudden increase in Ca demand and an unavoidable delay in Ca metabolism adaptation.
Post mortem collection of aqueous humour
Tetany is due to impaired Mg absorption from the rumen that cannot be compensated by absorptive or excretory adaptation, resulting in a net nutritional shortage of Mg and culminating in hypomagnesemia.
Lactating grazing cattle on lush pasture
Post mortem collection of vitreous humour
Copper deficiency
Ddx = lead poisoning, water intoxication, hypoxia,
In cats deficiency is associated with eating raw fish (thiaminase), poor food formulation (recent outbreak in UK cats) or sulphur contamination in food
Classic symmetrical haemorrhages in thalamus
Copper deficiency
“Sway-back” (congenital) in lambs or enzootic ataxia (acquired as neonates) in lambs and kids
Most common in lambs aged four to twelve weeks old
Ascending paresis/paralysis and ataxia
Pathogenesis = myelin degeneration
May be true copper deficiency, or high sulphur or molybdenum
Grossly – the brain is collapsed with bilateral symmetrical cavitation of the white matter
Ddx – Bluetongue and Border disease virus
toxic disease of the cns
Endogenous
Hepatic encephalopathy- shunts or acquired liver disease, Ammonia
Renal encephalopathy
Ketosis
Exogenous
List is practically endless!
See toxicology week
Both?!
Water deprivation/salt toxicosis
Seen in animals deprived of water that suddenly are allowed to drink ad lib
Pigs are particularly susceptible
botulinum protiene cleaves protien that allows for the fusing a acetyle choline lysosomes with axon
testnus toxin does the same but acts on inhibitry inter neurons cause=ing uncompramised release of acetyle choline
Decreased water intake -> dehydration and increased plasma sodium, which moves passively into CSF -> high sodium inhibits anaerobic glycolysis in the brain -> cerebral energy production decreased -> sodium cannot be actively transported from CSF back to plasma -> increased osmotic gradient -> with regained access to low-ion water, oedema -> increased pressure -> necrosis
neoplastic disease of the CNS
Neurones are post-mitotic therefore tumours of neurones are rare in adults
Neuroblastomas, ganglioneuroblastoma and ganglioneuromas are however seen in young animals
In the dog the most common location for a peripheral NB is dorsal cranial abdomen (peri-renal) due to remnants of neural crest
Olfactory neuroblastomas are rare tumours of the caudal nasal cavity and seen in older animals
Therefore, tumours of the CNS and PNS are typically from supporting structures
Meninges = meningioma- Most common in cats. good prognosis
Glial cells = glioma/glioblastoma- Over-represented in brachys, MOST COMMON BRAIN TUMOUR IN DOGS. poor prognosis
Peripheral nerve sheath tumours
PNSTs
Tumours of Schwann cells (Schwannomas or neurofibromas)
Brachial plexus – dogs
Skin of the eyelid - cattle
Peripheral nerve sheath tumours
PNSTs
Tumours of Schwann cells (Schwannomas or neurofibromas)
Brachial plexus – dogs
Skin of the eyelid - cattle
vescular diseasse in the CNS
Do animals have strokes?
Stroke in humans refers to an acute blockage of the vessels in the brain resulting in ischaemia to dependent tissue = infarction
More common in humans due to vessels already narrowed by atherosclerosis which is rare in animals
Infarction of the CNS of animals can otherwise be due to
Fat emboli – risk of orthopaedic surgery
Fibrocartilaginous emboli – associated with disc disease
Anything that causes hypercoagulability could cause an infarction in the brain-
In dogs shown to be associated with CKD or hyperadrenocorticism
Vascular brain disease in the cat-
Feline hypertensive encephalopathy
Feline ischaemic encephalopathies- Not in UK – Cuterebra larvae migrate to middle cerebral artery and occlude it resulting in massive infarction
forms of tse in farm animals
Naturally affected species-
Bovine spongiform encephalopathy – cattle, goats, exotic ungulates, felines (zoonotic!)- notifiable
Scrapie – sheep and goats- notifiable
Chronic wasting disease –cervids- notifiable
Camelid prion disease –dromedary camels (others?)
Transmissible mink encephalopathy – mink
- Two disease forms in BSE, scrapie and likely CWD
Classical form (original)
Atypical form (more novel)
H-type and L-type BSE
Classical form of tse
- Transmissible-
From dam to offspring
Lateral transmission (scrapie) - Affects more than 1 animal
- Wide age range
4-6 y in cattle (21 m-22 y)
≥18-24 m in sheep/ goats - Detectable prions in lymphoid tissue using standard tests
Distal ileum
Various lymph nodes in sheep
Atypical and classical cases have different legal consequences
Diagnosis by Western immunoblot or immunohistochemistry
Atypical tse
Sporadic/ spontaneous-
worldwide occurrence
* Single animals
* Usually older animals
≥8 y in cattle
≥3 y in sheep/ goats
* Prions NOT detectable in lymphoid tissue using standard tests
Infectivity in lymphoid tissue of sheep (mouse bioassay)
Atypical and classical cases have different legal consequences
Diagnosis by Western immunoblot or immunohistochemistry
pathogenisis of bse and scrapie
Classical forms
*Uptake of prions mainly via the digestivetract (tonsil, distal ileum)
*Spread via the vagusnerve to the CNS and/or haematogenous/ lymphoid spread in smallruminants and cervids
*Detection of prions in brain (obex)
Spread to periphery (e.g. muscle spindles)
Atypical formsSpontaneous (?) accumulation of prions in brainLimited spread to periphery although in sheep detectable in distal ileum (after oral challenge) and lymph nodes by mouse bioassay
Susceptibility to scrapie dependent on prion protein genotype
genetic component of scapies
- High susceptibility of VRQ/VRQ sheep with short incubation period
- Peripheral prion protein distribution in all VRQ/VRQ sheep
- Presence of ARR allele increases incubation period and reduces peripheral distribution
- High susceptibility of VRQ/VRQ sheep with short incubation period
- Peripheral prion protein distribution in all VRQ/VRQ sheep
- Presence of ARR allele increases incubation period and reduces peripheral distribution
take brainstem and cerebellum for screening and confirmatory test
Screening test: ELISA
Fast turn-around time
No anatomical context or discriminatory potential
*Confirmatory test: Immunohistochemistry, Western Immunoblot
WB: no anatomical context, good biochemical discrimination
IHC: full anatomical context, good discriminatory potential
clinical presentationn of BSE and scapies
*Slowly progressive neurological disease
*Duration: weeks to months (?acute disease)
*Usually changes in behaviour, sensation and movement as well asunspecific signs
*Lack of association between pathological findings and clinical signs
bse-
Changes in mental status, behaviour and activity:
* Apprehension, fear, nervousness
* Dullness may be present in atypical BSE
Changes in sensation:
* Over-reactivity to external stimuli, startle responses
Aversion to touch of the head/ neck
Flash test, stick test, clipboard test, bang test/ hand clap
Changes in posture and movement
* Ataxia, tremor, wide-based stance
* Difficulty rising predominant sign in atypical BSE
Non-specific signs:
* Loss of body weight/condition
* Reduced milk yield
* Bradycardia
* Positive scratch test in atypical BSE (?)
scrapie-
Abnormal behaviour and mental status
-Nervousness/ dullness, bruxism, separation from rest of the flock/ herd
*Abnormal sensation
Pruritus; over-reactivity to external stimuli less pronounced in sheep
Positive scratch test (‘nibble reflex’)
*Abnormal movement and posture
Ataxia, hypermetria
Wide-based stance, crouching
(Head) tremor
*Other neurological signs
Absent menace response, collapsing episodes (narcolepsy?), drooling
*Physical changes
Loss of weight/ body condition, fleece changes/ wool or hair loss
clinical presentation BSE
Changes in mental status, behaviour and activity:
* Apprehension, fear, nervousness
* Dullness may be present in atypical BSE
Changes in sensation:
* Over-reactivity to external stimuli, startle responses
Aversion to touch of the head/ neck
Flash test, stick test, clipboard test, bang test/ hand clap
Changes in posture and movement
* Ataxia, tremor, wide-based stance
* Difficulty rising predominant sign in atypical BSE
Non-specific signs:
* Loss of body weight/condition
* Reduced milk yield
* Bradycardia
* Positive scratch test in atypical BSE (?)
Clinical presentation: scrapie
Abnormal behaviour and mental status
-Nervousness/ dullness, bruxism, separation from rest of the flock/ herd
*Abnormal sensation
Pruritus; over-reactivity to external stimuli less pronounced in sheep
Positive scratch test (‘nibble reflex’)
*Abnormal movement and posture
Ataxia, hypermetria
Wide-based stance, crouching
(Head) tremor
*Other neurological signs
Absent menace response, collapsing episodes (narcolepsy?), drooling
*Physical changes
Loss of weight/ body condition, fleece changes/ wool or hair loss
Clinical presentation: CWD
Changes in behaviour & mental status
Separation from herd
Loss of fear towards humans
Dullness (droopy ears, low head carriage)
Teeth grinding
- Weight loss
- Other signs
Hypersalivation, increased regurgitation (risk of aspirationpneumonia)
Polydipsia/ polyuria (less frequent in elk)
Flaccid hypotonic facial muscles
Patchy retention of winter coat in summer
Ataxia (more frequent in elk), head tremor
Oesophageal distension, ruminal atony
Hyperexcitabilitywhen handled
Compulsive walking, circling
More susceptible to sudden death after handling
Public health and legislation typical for TSE
Disease notification (passive surveillance) or positive test (active surveillance)
- Cattle
Cull of cohort and recent offspring
May affect WOAH BSE risk status (currently controlled in GB)
Removal of specified risk material at slaughter most important to protect consumer - Sheep/ goats
Cull of herd/ flock if BSE
Cull of susceptible animals only (classical scrapie)
Movement restrictions (classical scrapie)
TSE monitoring of animals over 18 months for 2 years
Glia
Non-neuronal cells of the CNS
Macroglia-
Astrocytes
deendrites can be seen on staining and this destingushed them from microglia
Form the BBB and control blood flow
Microglia-
Glial cells
Phagocytes
Macrophage-monocyte lineage
Blood-brain barrier
Endothelial cells
Endothelial cell basement membrane
Foot processes of astrocytes
fluid going into brain must be tightly regulated
portals of entry into the brain
haematogenous
direct extension- nasal, spine, ear
retrograde axonal transport
examples of haematogenous entry into the brain
Thrombotic meningioencephalitis-
Calves
Histophilus somni- fibrin exudation of the meninges, devistating leasion in gray matter. liquefactive necrosis
meninges full of blood and so can be infected this way
Cryptococcus-
Cats
C. neoformans or C. gatti
bilateraly asymetrical easions- random
Strongylus vulgaris-Horse
Coenurus cerebralis
Sheep
Gid
Larval form of tapeworm Taenia multiceps
cavetous leasions
examples of direct extension entry into the brain
Otitis media- Pasturella multocida
fibrotic absess capsua and fluid center
Nasal-Aspergillus
Ameoba (Balamuthia)
very little between nasal sinuses and brain
common in dolceocephalic breeds
Discospondylitis- infection of intervertable discs
Trueperella pyogenes
Brucella
examples of retrograde axonal transport into the brain
the aetiologica agent travels in the nerve from axon to cell body
Listeria monocytogenes
From contaminated silage via damage to oral mucosa
Travel up cranial nerve to brainstem
Unilateral clinical signs- Drooling, facial paralysis
Unilateral micro-abscesses
Rabies-
Family Rhabdoviridae, genus Lyssavirus
Zoonotic, notifiable
Greatest threat to UK
Is seen in wild-ranging bats
Furious, dumb, paralytic forms
initaly replicates n muscle then acends via retrograde axonal transport in a peripheral nerve via a dorsal root ganglion and then enters the spinal cord and brain
Viruses of the nervous system
There are innumerable viruses that affect the nervous system
Most typically cause no gross lesions and will have similar histopathological findings
possibly- redening of meninges, cerebellar coaning
Perivascular cuffing with lymphocytes
Several viruses are associated with cerebellar hypoplasia-
BVD (cattle) and Bluetongue (sheep and cattle)
Feline panleukopenia
Swine fever
Clinical signs range from
Ataxia (kittens) – learn to live with it (altricial or infected as neonates)
Opisthonus – incompatible with life (precocial or infected in utero)
Several viruses are associated with hydrocephalus, porencephaly and hydrancephalus
Seasonal? – consider insect vectors
Neurolocalisation- Diffuse?
Multisystemic?
Abortions?
Severe mortality in young animals?
Milder flu-like signsin older animals?
Behavioural
Example:
Aujeszky’s disease virus
Notifiable
Mainly pigs
Suid herpes virus- Typical inclusions
“Mad-itch”
Respiratory, dermal, neuro and repro signs
Hydrocephalus
increased volume of fluid within the ventricles
Typically idiopathic congenital disease
In young animals will deform the skull
Chihuahuas and other brachys will have to some degree often with no clinical signs.
Disease states typically associated with true outflow impedance of the CSF.
Head pressing, inappetence, seizures, lethargy and altered mental status
Can be seen with BVD
Hydrancephaly
Loss of cerebral cortical tissue within a cranial vault of normal conformation.
The resultant cavity communicates with the ventricular system, and is filled with CSF.
Clinical signs may include lethargy, propulsive circling, head pressing, and blindness.
Develops as a result of the destruction of developing neural tissues
Typically associated with cerebellar hypoplasia and arthrogryposis
Worry about Bluetongue, Schmallenberg (and BVD)
Akbane virus (not in UK)
Porencepahly
Cystic structures within the neuropil that typically do not communicate with the ventricles
Less common
Akabane virus, BVD and malignant catarrhal fever
gross post mortemfindings in the spinal cord of horses infected with West Nile Virus
spread by vector
presents with inccorsination, hindlimb weakness
spinal cord will apear with asymetric haemorage and necrosis within the grey matter
clinical findings associated with Aujeszky’s disease in pigs
Notifiable
Mainly pigs
Suid herpes virus
Typical inclusions
“Mad-itch”
Respiratory, dermal, neuro and repro signs
gross post mortem findings associated with Bluetongue
Hydrocephalus
= increased volume of fluid within the ventricles
Typically idiopathic congenital disease
In young animals will deform the skull
Chihuahuas and other brachys will have to some degree often with no clinical signs.
Disease states typically associated with true outflow impedance of the CSF.
Head pressing, inappetence, seizures, lethargy and altered mental status
Can be seen with BVD
Hydrancephaly
Loss of cerebral cortical tissue within a cranial vault of normal conformation.
The resultant cavity communicates with the ventricular system, and is filled with CSF.
Clinical signs may include lethargy, propulsive circling, head pressing, and blindness.
Develops as a result of the destruction of developing neural tissues
Typically associated with cerebellar hypoplasia and arthrogryposis
Worry about Bluetongue, Schmallenberg (and BVD)
Teratogenic lesions
aGeneralised arthrogryposis of the appendicular skeleton (arthrogryposis multiplex congenita) and vertebral column malformation, including torticollis and kyphoscoliosis.bHydranencephaly, brachygnathia inferior and thickened flat bones of calvarium. Parasagittal section through the head exposing the severely dilated right lateral ventricle
forebrain function
FOREBRAIN (PROSENCEPHALON)
Cerebral hemispheres-Telencephalon
Thalamus- Diencephalon
Receiving/processing Sensory Information-
Auditory
Visual
Pain
Generates movement and posture
Role in generating appropriate consciousness/mentatin
Signs of Forebrain disease
Changes in mentation
Changes in behaviour
Circling (ipsilateral)
Head turn (ipsilateral)
Seizures
Postural response deficits (contralateral) – NOT WEAKNESS
Abnormal nasal mucosal response (contralateral)
Abnormal menace response (contralateral)
Central Blindness/ Central deafness
Brainstem Function
BRAINSTEM
Midbrain (mesencephalon)
Pons (Ventral metencephalon)
Medulla oblongata (myelencephalon)
Regulate vital reflex functions:
HR, RR, Temperature
Cranial nerves and nuclei (CNIII-XII)
Signs of Brainstem disease
Changes in mentation
Changes in behaviour
(Respiratory and cardiac abnormalities)
Paresis/paralysis- tetra/hemi
(ipsilateral)
Postural response deficits ( All or ipsilateral one side)
Cranial nerve nuclei dysfunction CN III-XII
- pupil size - menace response
- head tilt - nystagmus - gag reflex - spontaneous or positional strabismus - facial paralysis
Cerebellar Function
CEREBELLUM-Dorsal Metencephalon
Maintain balance and posture and tone
Modulates commands to motor neurons
Signs of Cerebellar disease
Intention tremors
Hypermetria ( all or ipsilateral), Dysmetria
Truncal ataxia broad-based stance
Mydriasis
Postural response delayed with an exaggerated response ( All or ipsilateral one side)
Menace response deficit (ipsilateral)
Vestibular dysfunction- head tilt (contralateral), nystagmus, strabismus
segments of the spinal cord that can be assesd for function
c1-c5
c6-t2
t3-l3
l4-s1
s1-s3
SPINAL CORD SEGMENTS: C1-C5 abnormalities on exam
tetri/hemi paresis/palegia
all 4 or one sided ataxia
postural reactions reduced in all 4 limbs
withdrawl/patellar reflexes normal or increased in all 4 limbs
perinela reflex normal
normal or increaded limb muscle tone in all 4 limbs
normal anal tone
Upper motor neuron neurogenic bladder dysfunction
other findings- horner syndrome/ respiritory difficulty
SPINAL CORD SEGMENTS: C6-T2
abnormalities on exam
tetri/hemi paresis/palegia
all 4 or one sided ataxia
postural reactions reduced in all 4 limbs
withdrawl/patellar reflexes reduced in one or both tls, normal Pls
perinela reflex normal
limb muscle educed in one or both tls, normal Pls
normal anal tone
Upper motor neuron neurogenic bladder dysfunction
other findings- horner syndrome/ respiritory difficulty
SPINAL CORD SEGMENTS: L4-S1
abnormalities on exam
para/mono paresis/palegia
pls only ataxia
postural reactions reduced reduced in one or both Pls
withdrawl/patellar reflexes normal tls, normal/increased pls
perinela reflex normal
limb muscle normal tls, normal/increased pls
normal anal tone
Upper motor neuron neurogenic bladder dysfunction
SPINAL CORD SEGMENTS: S1-S3
abnormalities on exam
no paresis/palegia
no ataxia
postural reactions normal
withdrawl/patellar reflexes normal
perinela reflex normal
limb muscle normal
normal anal tone
lower motor neuron neurogenic bladder dysfunction
SPINAL CORD SEGMENTS: S1-S3
abnormalities on exam
no paresis/palegia
no ataxia
postural reactions normal
withdrawl/patellar reflexes normal
perinela reflex normal
limb muscle normal
normal anal tone
lower motor neuron neurogenic bladder dysfunction
neuro exam abnormalities indicating Neuropathy/LMN c
mono, para or tetra paresis/palegia
no ataxia
postural reactions in one, two or all 4 limbs
withdrawl/patellar reflexes in one two ir all 4 limbs
limb muscle normal
normal anal tone
lower motor neuron neurogenic bladder dysfunction
other findings- quick onset of muscle atrophy, cranial nerve dysfunction also
findings in upper motor neuron disease
GAIT- Delayed generation, long-strided
MUSCLE TONE- Hypertonia
SPINAL REFLEXES- Normal to hyperreflexive
MUSCLE MASS- Normal, if chronic disuse atrophy
POSTURAL REACTIONS- Abnormal/absent
findings in lower motor neuron disease
GAIT- Weak, unable to support weight, short-strided
MUSCLE TONE- Hypotonia (Flaccid)
SPINAL REFLEXES- Hyporeflexia/areflexia
MUSCLE MASS- Normal (maybe abnormal if severe)
POSTURAL REACTIONS- Abnormal/absent
Cranial nerves
I: Olfactory
II: Optic
III: Oculomotor
IV: Trochlear
V: Trigeminal
VI: Abducens
VII: Facial
VIII: Vestibulocochlear
IX: Glossopharyngeal
X: Vagus
XI: Accessory
XII: Hypoglossal
CN II (Optic) dysfunction
HANDS OFF-
BLINDNESS
Normal to dilated pupils
HANDS ON-
Menace response deficit
Pupillary Light Reflex deficit
CN III (Occulomotor) dysfunction
MOTOR (External)
Extra-ocular muscles:
Medial rectus
Dorsal rectus
Ventral rectus
Ventrolateral oblique
PARASYMPATHETIC (Internal)
Sphincter pupillae muscle: Contraction of pupil
MOTOR (External)
Spontaneous Strabismus (ventral)
Abnormal vestibulo-ocular reflex
PARASYMPATHETIC (Internal)
Mydriasis
Absent pupillary light reflex
CN IV (Trochlear) dysfunction
Trochlear function:
Dorsal oblique
Trochlear dysfunction:
Lateral rotatory strabismus (cats)
CN V (Trigeminal) dysfunction
THREE branches:
Ophthalmic: Sensory
Maxillary: Sensory
Mandibular: Sensory and Motor
Sensory deficits:
Absent palpebral reflex
Medial (ophthalmic branch)
Lateral (maxillary branch)
Reduced facial sensation
Abnormal nasal mucosal response
Motor deficits
Unilateral: loss of temporalis mass and other masticatory mm
Bilateral: dropped jaw
CN VI (Abducens) dysfunction
Function:
Lateral rectus muscle
Retractor bulbi muscle
Dysfunction
Medial Strabismus
Abnormal Vestibulo-ocular reflex
CN VII (Facial) dysfunction
HANDS OFF
Facial asymmetry
Absent movement of ear, eyelid, upper lip and nostrils
Drooling Saliva
Dropped ear
HANDS ON
Absent palpebral reflexes
Lack of blink in response to menace response and testing facial sensation
Dropped lip commissure
CN VIII (Vestibulocochlear) dysfunction
Head tilt
Nystagmus: Spontaneous or positional or both
Positional ventrolateral Strabismus
Vestibular Ataxia
Abnormal Vestibulo-ocular reflex
CN IX (Glossopharyngeal) and X (Vagus) dysfunction
Reports of dysphagia (IX and X)
Reduced/absent gag reflex (IX and X)
Inspiratory dyspnoea [laryngeal dysfunction] (X)
Regurgitation [Megaoesophagus] (X)
CN XI (Accessory) dysfunction
De-innervation of neck muscles:
Sternocleidomastoideus
Trapezius
Sternocephalicus
Brachiocephalicus
Atrophy of neck muscles
Torticollis?
CN XII (Hypoglossal) dysfunction
Tongue deviation towards the side of dysfunction
Dentition of rodents
Continuously growing insisors
Enamel only on front of insisors
omniverous
Most common tumours in rats
Mammary fibroadenima
Pituitary tumour
Skin tumours- zymbals gland tumour, dermal fibroma/fibrosarcoma
Most common tumours in mice
Most common tumours in mice
Mammary tumour- adebicarcinoma
Lymphoma/leukemia
Common tumors in outbred CD-1 mice
Lymphoma
Skin subcutis tumour
Mammary tumour
Pathology of rodent skin masses
Hard to tell macroscopically
Skin mass or abdominal cell tumours?
Species narrows down differentails
Cells of origin-
Epithelial cell tuour
melanoma
Spindal cell tumours
Round cell tumours
Differentials- absess, haematoma, fracture
Tumours of epithelial origin in rodents
Papilloma
Squamos cell carcinoma
Trichofolliculoma- from hair follicle
Tricopitheliomoa- from hari follicle
Scent gland tumours
Mammary tumour
Tumours of epidermal origin in rodents
Papilloma- benign
Common
Single or multiple
Exophytic/ polupoid
Viral origin possible
Squamous cell carcinoma-
Less common
Often ulcerated
Hair follicle tumours in rodents
Trichofolliculoma-
Most common epithelia tumour of guinie pigs
Benign
Solitary, dome shaped, firm subcutaneous nodules, <2cm
Central pore with keratien debris
Common in dorsal lumbar region
Trichoepithelioma
Common in hamsters
Associated with poluoma virus infection
Common on face-lips pinna, ear canal neck
Discrete, well circumscribed
Multiple and cystic
Scent gland tumours in rodents
Modified sebaceous glands
Ventral abdomen in gerbals, flank in hamsters
Hyperplasia ad sebaceous and squamous cell neoplasms
Benign or malignant
Mammary tumours in rats
Fibroadenomsa
Benign
Wel demarcated in subcutis
May have underlying pituitart tumour
Mamamary tumours in mice and other rodents
Tend to be more glandular
More likely malignant- adenocarcinoma
Do metastisise esp in mice
Tumours derived from spindal cells (mesenchymal) in rodents
Lipoma
Liposarcoma
Fibroma
Fibrosarcoma/spindle cell sarcoma
Microchip related sarcoma
Lipomas in rodents
Common in guinea pigs
Usually well circumscribed
Soft,fluctulant
Fibroma/fibrosarcoma in aeging rodents
Firmer than lipoma
Subcutaneous masses
Spindle shaped cells
Viriable collagen and mitotic activity
Metasteses uncommon eve with malignant tumours
Melanoma in rodents
Hamsters and rodents
Face, ears, neck, feet
Dark irregular mass
Can metastisise
Round cell tumour/lymphoma in rodents
Masses- often equate to affted lympnodes- groun, axilla, neck
Lymphoma may just aft lymphnodes or include other organs
In hamsters- epitheliotic lymohoma- alopecia and scalling
Other relativly common tumours of skin in rodents
Osteosarcoma- mice
Haemangiosarcoma- mice
Hibernoma- rats
Malignant fiberous histiocytoma
Histiocytic sarcoma
Zymbals gland tumour
not particularly common
Non neoplastic masses in rodents
Cysts
Pyogranulomas
Absesses especially in sebaceous gland-
Cliterola
Zymbals gland
Pyogranuloma in rodents
Head or jaw
From fighting or trauma
Typicallu pyogranulomas
Gram +ve cocci ususally
Zymbals gland abscess
Rodents
Modified sebaceous gland at base of ear
Common site for absess formation
Can present as otitis externa
Ddx tumours
when to perform a CSF tap
Indications
Suspected inflammatory or neoplastic lesions of the central nervous system
Contraindications
Atlanto-occipital collection contraindicated if signs of brain herniation are present.
Advantages
Findings often highly significant and of good diagnostic and prognostic value.
Disadvantages
Results of analysis may be unrewarding or non-specific.
Need for general anaesthesia.
If dramatic drop in CSF pressure created during withdrawal of CSF, this may result in tentorial herniation and convulsions.
sites for a csf tap
lumbar cistern
cereblomedullary cistern
Standard CSF analysis includes
total nucleated cell count (TNCC)
red blood cells (RBC)
total protein (TP) concentration
cytological evaluation.
Normal CSF does not contain RBC and has a TNCC of less than 5 cells/μL.
CSF TP concentration should not exceed between 25–30 mg/dL at the cerebellomedullary cistern and 45 mg/dL at the lumbar subarachnoid space
CSF can also be tested with PCR for infectious diseases
Neospora
CSF tap - inflammation
pugs and yorkshire terries have idiopathic inflamatory diseases
tap shows massive amounts of inflamitory cells
some involve high numbers of eosinophils- eosinophilic meningitis
steriod responsive meningitis arteritis involves high no of neutrophils in csf
CSF tap - neoplasia
can see metastatic carcinoma- cels displaying adhearence and malignant criteria. not often epithelil tumours in spinal cord so is a metastisis
lympoma can be seen
csf fluid findings in disk rupture
increased number of macrophages containing material- possibly myelin
csf fluid findings in lysosomal storage disease
macrophage with globules in cytoplasm that pick up staining
myasthenia gravis
Pathogenesis: Reduced number or function of nicotinic acetylcholine receptor
Acquired: aberrant immune process results in development of autoantibodies produced against the nicotinic acetylcholine receptor
Congenital: mutations in choline acetyltransferase gene, acetylcholine esterase collagen gene or the receptor itself
Pathophysiology: Due to a lack of communication from the nervous system to muscle.
Clinical signs: Weakness, dysphagia, regurgitation (mega-oesophagus).
Diagnosis
Rule out a myopathy- Creatine kinase (CK)
Response to edrophonium chloride (Tensilon test)-
Inhibits the enzyme acetylcholinesterase
Weakness should improve within 30-60 seconds, with effect persisting for 3-5 minutes
Serology for AChR antibodies
Thoracic radiography
can be caused by thymic mass
Horner’s syndrome
Pathogenesis: Loss of sympathetic innervation to the globe and adnexal structures.
Pathological change at one of several sites:
First order: brain stem to T1-T3 spinal cord lesions.
Second order: (pre-ganglionic fibers) arising in spinal cord segments T1-T3 and joining the vago-sympathetic trunk via the rami communicators.
Third order: (post-ganglionic fibers) arising at cranial cervical ganglion rostrally joining the trigeminal nerve at the trigeminal ganglion.
Pathophysiology and clinical signs:
reduction of sympathetic nerve supply to smooth muscle of orbit
third eyelid protrusion, ptosis, miosis
Underlying cause differs between species
Canine = idiopathic
Feline = otitis media/nasopharyngeal polyip/iatrogenic
Equine = guttural pouch disease
Also seen with grass sickness (see later)
Diagnosis
1% phenylephrine applied topically to both eyes- mydriasis in the affected eye with no response in the control eye
Cats – head radiography or CT
Horse – scope guttural pouch versus imaging of the neck depending on other clinical signs/history
Equine grass sickness
Equine dysautonomia
Pathogenesis
Degeneration of autonomic neurons in the brain, ganglia, and enteric nervous system
Due to Clostridium botulinum toxin
Signalment-
Adult horses at grass
Clinical signs-
Tachycardia, ileus, colic
Chronic weight loss
Acute colic and gastric reflux
Bilateral Horner’s syndrome
Diagnosis-
Histo
Biopsy of rectal or ileal samples in live animals
Cranial mesenteric or cranial cervical ganglion post mortem
Chromatolysis
canine masticatory myositis (CMMM)
atrophy of the temporal muscle symetricaly due to imuune system attaching the muscle
right sided heart faliure
Results in back up of blood as right side cannot receive it properly and so results in
Congestion of peripheral tissues-
Dependent oedema and ascites- blood ooses from vena cava- Transudate fluid
Liver congestion- signs related to impaired liver function
Gi tract congestion- anorexia, gi distress, weight loss
left heart faliure
Results in decreased cardiac output as left ventricle cannot pump blood-
Activity intolerance, signs of decreased tissue perfusion
Inability of left atrum to receive blod results in Pulmonary congestion-
Impaired gas exchange- cyanosis and signs of hypoxia
Pulmonary odema- cough with frothy sputum, orthopnea, paroxysmal nocturnal dyspnea
What is CHD?
Congenital heart disease (CHD) refers to a group of heart conditions that are present at birth in animals.
CHD is relatively common in veterinary medicine, and it can affect many different species of animals.
Examples include
Ventricular septal defect (VSD): A hole in the wall that separates the two lower chambers of the heart.
Atrial septal defect (ASD): A hole in the wall that separates the two upper chambers of the heart.
Pulmonic stenosis: Narrowing of the valve or artery that leads from the right ventricle to the lungs, which can lead to reduced blood flow to the lungs.
Patent ductus arteriosus (PDA): A blood vessel that fails to close after birth, leading to abnormal blood flow between the aorta and pulmonary artery.
Tetralogy of Fallot (TOF): A combination of four heart defects, including a ventricular septal defect, pulmonary stenosis, an overriding aorta, and right ventricular hypertrophy.
Vascular ring anomalies such as persistent right aortic arch
Ventricular septal defect
The most commonly reported CHD in cattle
Also seen in cats and miniature swine, occasionally in dogs- Heritable in English Springer Sps
Typically located in the perimembranous portion of the septum- high in the ventricular septum
Left to right shunting of blood- he pressure in left ventricle higher than right, too high pressure for right ventrile so blood flows back into pulmonary vessel-> pulmonary hypertension
Atrial septal defect
In the foetus, the atria are connect by the foramen ovale which closes at/ shortly after birth. Failure to close (patent foramen ovale) is not the same as true ASD, which is due to a true hole in the interatrial septum- can teel difference as in asd the scarring form the patent foramen ovale should be to the right
Left to right shunting- Less blood can come in from vena cava so backs up-> right-sided heart failure= ascites
Pulmonic stenosis
Overrepresented in brachycephalic dogs such as Bulldogs, but also JRTs, Labradors and Samoyeds
Fusion or dysplasia of the pulmonic valve leaflets
May cause thickening of right side of heart as it eeds to work harder to force blood past stentic gap->
Right-sided heart failure
Patent ductus arteriosus
The most common CHD of dogs
In the foetus, the Ductus arterious shunts blood from Pulmonary Artery to aorta so as to bypass the lungs
After birth failure to close results in Aota to Pulmonary Artery shunting-> oxygenated blood that is intended for body goes to pulmonary arter- less oxygenated blood in body- pressure in lungs as they are overwhelmed with amount of blood->-> pulmonary hypertension and LHS failure
Results in base murmer
Persistent right aortic arch
PRAA not a true CHD as involves vessels outwith the heart
As a foetus, most structures develop symmetrically, this is true also of vessels of the heart with unnecessary duplicated structures regressing.
The aorta should curve to left of trachea- in an animal with PRAA, the right fourth arch, instead of the left, becomes the functional aorta. The ligamentum arteriosum (LA) extends between the left pulmonary artery and the anomalous Right Aortic Arch, causing constriction of the oesophagus causing megaoesophagus
Persistent right aortic arch
PRAA not a true CHD as involves vessels outwith the heart
As a foetus, most structures develop symmetrically, this is true also of vessels of the heart with unnecessary duplicated structures regressing.
The aorta should curve to left of trachea- in an animal with PRAA, the right fourth arch, instead of the left, becomes the functional aorta. The ligamentum arteriosum (LA) extends between the left pulmonary artery and the anomalous Right Aortic Arch, causing constriction of the oesophagus causing megaoesophagus
Main issue in brachycephalic rabbits
compared to dogs, which primarily have breathing issues, is a blocked nasolacrimal duct.
Nasolacrimal duct blockage in rabbits
Watery eyes= epiphora
May have purelant discharge
Inflammation and infection of the duct= dacryocystitis
Also more prone to malocclusion
Snuffles
Disease of rabbits
Aetiological agent
Pasturella multocida
Pathology
Rhinitis -> turbinate atrophy
Pneumonia
Abscesses
Otitis media -> head tilt
pasturella in rabbits
Pneumonia-Pseudomonasspp,Bordetella bronchiseptica,Staphylococcus spp, andStreptococcushave also been isolated
Carriers of P. multocida can be identified by an indirect fluorescent antibody test on nasal swabs.
Common comensal
An ELISA test to detect antibodies againstP multocidamay also help detect carriers.
It is important to remember that Pasteurella can be sampled from a large percentage of clinically normal rabbits, and culture results must be interpreted carefully
PCR can discriminate between different isolates and is commercially available.- Not every strain of Pasteurella is pathogenic.
Five serotypes (strains) of Pasteurella have been described, with two of them most commonly involved in pathologic conditions in rabbits.
Pathology of cranial ventral lesion of lung lobe
Seropuralent discharge from nose
Abcesses in lung lobes
Uterine endometrial adenocarcinoma in rabbits
The most common neoplasia of the rabbit reproductive tract and probably the most common neoplasia of any body system of female rabbits
Carcinoma = malignant
80% will metastasize
lungs
Atrophic rhinitis of pigs
Bordetella bronchiseptica and Pasteurella multocida
Bordetella phase-
Virulence factor:
Dermonecrotic toxin (DNT)
Pasteurella phase-
Virulence factor
Pasteurella multocida toxin (PMT)
Pathogenesis and pathophysiology:
DNT
Kills epithelial cells allowing access of PMT to submucosa
PMT
Increases osteoclasts and inhibits osteoblasts-> turbinate atrophy
Bacterial pneumonia - EP
Enzootic pneumonia (EP) is the most common respiratory disease seen in pigs in the UK.-
Mycoplasma hyopneumoniae
The primary agent of the porcine respiratory disease complex (PRDC)
PRRSV, PCV2, Swine influenza virus, Pasteurella multocida, Actinobacillus pleuropneumoniae, Haemophilus parasuis, Bordetella bronchiseptica
Other influencing factors are housing conditions and management practices (like crowding, poor air quality, stress)
Pig specific
Present in more than 80% of pig herds in the UK
Clinical signs
3-5months
Low-grade to severe cough
Mild fever
Slowed growth
Secondary more sever infections
Gross lesions-
Classic bilateral cranioventral
Histo-
Bronchopneumonia
Diagnosis-
Mycoplasma spp are difficult to culture - PCR
Aetiological agent of atrophic rhinitis in pigs
Bordetella bronchiseptica
Pastrurella multocida
Aetiological agent of porcine respiritory disease complex
Bordetella bronchoseptica
Pasturella cultocida
Prrsv
Pcv2
Swine influenza virus
Actinobacillus pleuropneumoniae,
Haemophilus parasuis,
Bacterial pneumonia - Pleuropneumonia
Actinobacillus pleuropneumoniae
Clinical signs-
fever, anorexia, reluctance to move, respiratory distress, and sudden death
Gross lesions-
severe fibrinonecrotic and hemorrhagic pneumonia with accompanying fibrinous pleuritis and/or pericareditis
Diagnosis-
culture
aetiological agent of Pleuropneumonia
Actinobacillus pleuropneumonaie
aetiological agent of Enzonotic Pneumonia
mycoplasma hypopneumoniae
Bacterial pneumonia - Glasser’s disease
Glaesserella (Haemophilus) parasuis
Fibrinous polyserositis and polyarthritis, but septicemia with sudden death and bronchopneumonia also can occur
Diagnosis-
Bacterial culture or PCR
aetiological agent of glassers disease
Glaesserella parasuis
Viral causes of pneumonia in pigs
Implicated viruses-
PRRSV (porcine reproductive and respiratory syndrome virus)
Coronavirus
Swine Influenza virus
Circovirus (PCV2)
Inhaled-
Contribute to cranioventral lesions in association with bacterial bronchopneumonia
More typical of viral pneumonia is INTERSTITIAL PNEUMONIA
clinical signs of swine influenza
Sneezing, coughing and difficulty breathing
Abortions (in some cases)
Nasal and ocular discharge
Pyrexia
Loss of appetite
Weakness
swollen and red eyes
Mulberry heart disease
disease of pigs
Due to vitamin E/selenium deficiency- Anti-oxidants
Cardiomyocyte and vascular necrosis- Polyphasic
Important differential for cardiac necrosis in pigs are viruses in the picornavirus family- Foot and Mouth Disease Virus
hypertrophic cardiomyopathy (HCM) in cats
The most frequent heart disease in cats is hypertrophic cardiomyopathy (HCM)
Heritable in Bengals, British Shorthair, Maine Coon, Persian, Ragdoll, and Sphynx cats
Proven genetic basis in Maine Coons and Ragdolls- Myosin binding protein
Diastolic failure-
Inability of the left ventricle to relax and therefore fill fully
Due to areas of fibrosis and left ventricular hypertophy
Pulmonary oedema
Pleural effusion
Heart weight >20g
LV and IVS thickened
Dilated left atrium
Thrombus in left atrium
Thromboembolism in aortic trifucation
Dilated cardiomyopathy in cats
Taurine deficiency
Making a come back thanks to weird diets
Dilated cardiomyopathy in dogs
Genetic- Doberman Pinschers, Boxers, Great Danes, German Shepherd Dogs, Irish Wolfhounds, Scottish Deerhounds, Newfoundlands, Saint Bernards, and Labrador Retrievers
Dietary- Taurine
Gluten free?
Doxorubicin
Parvo
Insidious combination of left and right sided failure
Systolic failure
Arrhythmogenic right ventricular cardiomyopathy
Boxers
Rarely in cats
Genetic defect- Striatin
Syncope and sudden death
Arrythmia
Mitral valve disease in dogs
Myxomatous Atrioventricular Valve Degeneration
CKChSp massively over-represented
Cause unknown
Fibrous layer of the mitral valve undergoes myxoid degeneration
Leaky valve results in back flow of blood into left atrium
Left sided heart failure
Endocarditis in dogs
Bacterial endocarditis arises from adhesion of the microorganisms to the endocardium, leading to death of the endothelium and formation and adherence of a thrombus within which large colonies of bacteria proliferate.
Streptococcus sp., Staphylococcus sp. and E. coli are frequently implicated as the etiologic agents in many species.
Additionally, Erysipelothrix rhusiopathiae is often isolated in pigs and (occasionally) dogs, while Bartonella sp. is more specific to the dog or the cat.
Arcanobacterium pyogenes is a common pathogen in cattle and Actinobacillus equuli can occasionally cause valvular endocarditis in horses.
Look for the underlying cause
IV catheter?
Pericardial effusions
The sac around the heart can fill with fluid for several reasons
The most common PE in dogs would be haemorrhagic and due to a ruptured haemangiosarcoma
PE is rare in cats but most commonly associated with heart failure
In sheep a transudate/modified transudate with fibrin clots is most indicative of Clostridium perfringens type D
Fibrinosuppurative pericarditis in cattle is secondary to penetration of a wire from the stomach
All will impede function of the heart due to compression
Cardiac tamponade
Right side most vulnerable
Cat flu
IMPORTANT – influenza virus not involved!
Multifactorial:
Viruses-Herpes
Calicivirus
Bacteria- Chlamydophila/Chlamydia felis
Bordetella bronchiseptica
Mycoplasma felis
also Polyps- cause of polyps is a little unclear but we presume it is a proliferative response to chronic infection or inflammation, for example chronic otitis
Clinical signs-
Rhinitis, sinusitis, conjunctivitis
Pneumonia rarely
Cryptococcus in cats
The most common non-dermal fungal disease of cats
C neoformans or C gattii
From pigeon faeces
Zoonotic
Asymptomatic airborne colonisation of the respiratory tract
Nasal form most common
Cutaneous, systemic (including ocular) and CNS forms all reported
Cytology - Classic yeast form with virtually pathognomonic thick capsule
Lungworm in cats
Aelurostrongylus abstrusus
Relatively rare compared to canine lungworm
Pleuritis in cats
Pleuritis (pleurisy) is inflammation of the pleural cavity
Thoracic empyema/pyothorax is the accumulation of pus in the pleural cavity
Bite wound?
Typically polymicrobial-
Escherichia col
Pasteurella spp.
Actinomyces spp.
Nocardia spp.
Streptococcus spp.
Staphylococcus spp.
Corynebacterium spp.
62% survival?
Feline asthma
Allergic lower airway disease
Key clinical sign is coughing-
Cats with heart failure do not cough c.f. dogs
Inspiratory wheeze- Marked effort on inspiration
Overinflated/flattened diaphragm
Bronchoalveolar lavage-
eosinophils
Primary lung tumours in cats
Pulmonary adenoma/carcinoma
Seen in all species
Pulmonary adenocarcinoma relatively common in aged cats
Pulmonary adenocarcinomas in the cat most commonly metastasize to the digit-
Lung-digit syndrome
Goblet cells and cilia in a toe tumour!
Common URT infections in horses
‘Snotty nose’ is a common presentation, particularly in communal yards
Clinical Signs-
Bilateral, mucoid/mucopurulent nasal discharge
Snorting/URT stertor/coughing
Aetiology
Viral: Herpes (EHV1 or 4)
Equine rhinitis A & B viruses (Picornaviridae)
Adenoviruses
Bacterial: Normally secondary infection-
Strep. equi zooepidemicus
Treatment
Usually none required – 1st line antimicrobial therapy only if absolutely necessary
URT Viral infection
Altered mucociliary clearance-> mucoid discharge (Obstruction to drainage
Cyst / Neoplasia
Trauma)
Stagnation of mucus within sinus
Secondary bacterial infection -> purulent discharge (Dental Disease
Accumulation of pus (empyema)
Equine Sinusitis
Objectives of therapy
Total remove infection / diseased tissue
Restoration of normal drainage and mucociliary clearance
Prevent recurrence
1o - Acute/uncomplicated-Antimicrobials – TMPS or Penicillin
Mucolytics & Controlled exercise
1o - Chronic- + sinus trephination and regular lavage
2o – Dental, trauma, neoplasia- + treatment/removal of inciting condition
Secondary Dental sinusitis in horses
The roots of the maxillary molar cheek teeth lie within the maxillary sinus space
Covered by very fine layer of alveolar bone and sinus periostium
Apical tooth root infections of these teeth will result in sinusitis
Less profuse but often malodourous nasal discharge
Chronic sinusitis, non-responsive to medical Tx
Must examine the oral cavity / occlusal surfaces of teeth to assess for any pathology.
Radiographs are usually diagnostic
Equine Sinus Cysts
Can occur in horses of any age
3rd most common sinunasal disorder
Large expansile structures which can distort nasal structure
Clinical signs
Serous/Mucoid unilateral nasal discharge
Facial distortion(maxillary or frontal)
Obstruction to nasal airflow
Abnormal respiratory noise
Treatment
>90% success rate with extirpation
via sinus flap surgery
Sinus Trephination
Frontal sinus or the caudal maxillary sinus
Placement of a indwelling foley catheter
Allow high volume lavage and instillation of antimicrobials
Facial flap surgery
Better surgical access to sinuses
Improve drainage;
Breakdown bullae CMS RMS
Create ventral fistula between MS and middle meatus
Progressive Ethmoid Haematoma
Non-neoplastic
Progressive sub-mucosal haemorrhages
Can develop in nasal or sinus portion of ethmoids
Intermittent epistaxis (altered/ ‘mucky’ blood)
Varying degrees of nasal/sinus obstruction
Treatment
Small lesions:
Intralesional formalin
Large lesions:
Surgical resection via sinus flap
Prognosis-
Fair
High rate of recurrence
Strangles
Clinical Signs-
Initial Fever
Inappetance
Dull, lethargy
2nd fever
URT obstruction
Dyshpagia
Discharge
Fomitic spread of infected material-Inhalation or ingestion of S. equi
Colonisation of URT epithelium/tonsil tissue-2-6d Incubation period
Rhinitis and pharyngitis
Spread to local lymphatics-
Submandibular, retropharyngeal, parotid. Systemic bacteraemia can occur-Seeding in distant lymphatic tissue
Lymphadenopathy & Abscess formation-GP Empyema, Abscess rupture
diagnosis-
Sample sites
Nasopharyngeal swabs
Purulent discharge
Guttural pouch lavage- detects carrier horse
To confirm disease
History and clinical signs
Culture + qPCR on any of above
To confirm resolution or ID carrier
qPCR on 3 sequential NP swabs
qPCR on 1 NP swab and GP lavage
Analysis methods:
Bacterial culture Can have false positives
Quantitative PCR analysis (qPCR) Better sensitivity and specificity
Supportive therapy during acute phase of infection;
Nursing support
Non-steroidal anti-inflammatory medication-Flunixin meglumine, 1.1mg/kg IV or PO BID
Encouraging drainage of abscesses- Hot pack, surgical lancing, daily cleaning/lavage
Antimicrobial therapy
Reserve for very sick/compromised patients.
S. equi equi usually sensitive to Penicillin (20-25mg/kg IM BID) will have benefit in early disease, but may interfere with development of natural immunity
Guttural Pouch Disease
Inflammation/infection of GP
Prone to the same pathophysiology for infection as the sinuses
Clinical signs similar to GP mycosis, +/- purulent discharge
Chronic empyema _> chondroid formation
Treatment - Removal of inspissated material
- Lavage and topical antibiotic
Crystalline penicillin admixed with gelatin
instilled into gutturall pouch
Any horse with purulent material in the GP should be tested for Strep. equi equi infection GP’s are a predilection site for strangles Close association with lymphatic structures of the URT (retropharyngeal LN’s)
Guttural Pouch Mycosis
Aspergillus (e.g. A. fumigatus) - Opportunistic infection
Presence of fungal plaques on the GP mucosa
Predilection sites over the Internal (ICA) or External ECA) carotid arteries
Clinical Signs
Depend on location of fungal plaque, and degree of local tissue damage/inflammation;
Erosion of ICA or ECA-
Epistaxis
initially intermittent,
progressing to possible exsanguination
Mucosal Only-
No clinical signs
Mild, intermittent mucoid discharge
Cranial nerve dysfunction-
Pharyngeal paralysis
Laryngeal hemiplegia
Facial paralysis
Horner’s syndrome
Pain in parotid region
Stiffness in the neck
Reduced appetite
Diagnosis-
History of repeated episodes of unilateral epistaxis
Endoscopy – Cautious examination of the GP
Treatment-
Medical management with systemic or topical anti-fungals is rarely successful- Only for sub-clinical cases
Where there is evidence of haemorrhage, horse should be referred for
ligation of the internal carotid artery- Need to occlude artery distal and cranial to the lesions
Prognosis-
Guarded – Complications are common
Poorer prognosis if significant neurological dysfunction present
Recurrent Laryngeal Neuropathy
The RLn contains the longest motor axons in the horse, measuring up to 2.5 m in length in Draft and Thoroughbred horses, with the left nerve being30 cm longer than the right in tall breeds
Left rln occurs more than right
URT Obstruction
Causes marked inspiratory effort
Dynamic collapse of soft tissues due negative pressure associated with inspiration
Inspiratory STRIDOR or STERTOR
treatment-
Ventriculectomy
Ventriculocordectomy
Laryngoplasty
Arytenoidectomy
Neuromuscular pedicle graft
Equine ‘Recurrent Airway Obstruction’ (RAO)
Syndrome of mature horses.
Generally > 7-years-old
A condition of small airway obstruction characterised by;
Neutrophilic inflammation (bronchiolitis)
Mucus hyper-secretion
Bronchoconstriction / Bronchospasm
Previously known as Equine Heaves, COPD
Allergen induced hypersensitivity response;
Commonly associated with stabling
– high exposure to allergens- Poor environment, ventilation and management can all contribute
Summer Pasture-associated RAO – induced by environmental pollens
respiritory pattern- LRT Obstruction
Thickening, inflammation and mucus
Causes increased expiratory effort
Small airways held open during inspiration
Early collapse during expiration
Acute condition is reversible with;
Removal of inciting cause / Environmental management
Medical therapy- Bronchodilators, Anti-inflammatories (corticosteroids)
Chronicity can result in irreversible change;
Metaplasia of epithelium
Permanent obstruction
Alveolar over-inflation -> emphysema
Bronchovesicular sounds- Increase airflow Harsh intensity
Wheezes - Air passing through narrow airways- Bronchoconstriction
Crackles/Rales - Air passing through fluid & mucus
Equine Inflammatory Airway Disease
Can affect any age of horse, but more common in younger horses
Multifactorial (or multiple aetiologies proposed) -
Non specific inflammation: Neutrophilic, eosinophilic or mast cell-associated
Post-viral infections
Bacterial aetiology
Parasitic involvement
Secondary to pulmonary haemorrhage
Very often sub-clinical when at rest
Common clinical findings
Exercise intolerance and poor performance
Intermittent cough associated with exercise
Varying degrees of mucus accumulation
Equine Asthma - Diagnosis
BAL fluid cytology
Specific and informative
neutrophilic response
Medical therapy
For clinical RAO, or IAD when associated with poor performance
BRONCHODILATORS
Anticholinergics
Atropine- Very effective when given IV for acute episodes
Hyoscine butylbromide- Potent and rapid bronchodilatory effect
Ipratropium - Given as inhalational therapy
Β2-agonists
Clenbuterol-Bronchodilator, anti-inflammatory and improves mucociliary clearance
Salbutamol/Albuterol -Inhalataional therapy
Medical therapy
For clinical RAO, or IAD when associated with poor performance
CORTICOSTEROIDS
Oral/systemic
Prednisolone- Only licensed oral steroid in horses
Dexamethasone- More potent than prednisolone
Inhalational
Beclomethasone,
Fluticasone
Both have more potent anti-inflammatory action and reduced systemic side effects
Systemic-
Acute exacerbations
Establish ‘control’ of allergy
Restore normal function
Inhalational- Better for long term control
Minor relapses
Can tailor treatment to response
Environmental Management
Essential in the treatment of any form of lower airway inflammation
Maximise time at pasture
Reduce exposure to dust / spores
Dust extracted bedding – keep clean
Avoid hay where possible- Feed haylage , Soaking or steam hay
Optimise ventilation when indoors/ stabled
Turn horse out before mucking out
Stable away from muck heap or busy thoroughfares
May require change of location / yard
Kennel cough
Infectious canine tracheobronchitis
= Canine infectious respiratory disease (CIRD) complex
Infectious tracheobronchitis that is usually self-limiting unless complicated by bronchopneumonia in unvaccinated pups or old/immunosuppressed dogs
Frequently involving several infectious agents:
Canine parainfluenza virus (CPIV)
Canine adenovirus type 2 (CAV-2)
Canine herpesvirus (CHV-1)
Bordetella bronchiseptica
Mycoplasma canis and M. cynos
Usually apparent 3-7 days after exposure
Cough (dry or productive), retching - particularly during exercise and when on lead
Nasal +/- ocular discharge, sneezing
In most cases recovery after one to three weeks
Pathogenesis-
Infection of respiratory epithelial cells by viruses and/or Bordetella
Cell damage caused by viruses and bacterial toxins
Inhibition of ciliary clearance by damage to ciliated cells
Potential secondary bacterial infections (streptococci, Pasteurella spp.)
Different mix of infectious agents may produce same clinical signs
Canine parainfluenza virus (CPIV)
Causes mild respiratory disease
Frequently (>50% cases) isolated from dogs with respiratory disease
More severe disease if in combination with Bordetella
Canine adenovirus (CAV)
CAV-2 causes respiratory disease
Not commonly associated with kennel cough in UK/US possibly due to good adenovirus vaccine uptake
CAV-1 causes hepatitis (ICH) (but has been reported to cause respiratory disease as well)
Canine herpesvirus (CHV-1)
DNA virus – IN eosinophilic IBs
fatal systemic disease in young puppies (< 2wks old)
‘fading puppy syndrome’
thermotropic virus (<35.5oC)
mild tracheobronchitis in adults (part of ‘kennel cough’ complex)
Multifocal necrotising hepatitis with eosinophilic intranuclear IBs (also necrotising nephritis)
Bordetella bronchiseptica
Small Gram-negative rods
Main phenotypic traits
Motile
Strict aerobe
Glucose non-fermentative
Oxidase-positive
Commensal of the upper respiratory tract
Endogenous or exogenous infection transmitted by aerosol or direct contact
Diagnosis by PCR or culture
Treatment: doxycycline or amoxicillin with clavulanic acid
Intranasal multivalent vaccines
Canine respiratory coronavirus (CRCoV)
Associated with mild respiratory disease
Highly contagious
Vaccine under development (RVC/Zoetis)
Distinct from canine enteric coronavirus (CECoV) (mild diarrhoea in young dogs)
CECoV vaccines do not cross protect
Canine pneumovirus, CnPnV
Discovered in 2010 in NE USA while looking for novel respiratory viruses in animal shelters
Closely related to murine pneumovirus and human respiratory syncytial virus (RSV)
More recently been isolated from non-shelter dogs
Often co-infections with other respiratory viruses
RVC involved in a large prevalence study (early data ~25-60% +ve, 93% have Abs)
Canine influenza virus (CIV)
All segments of viral genome derived from equine influenza
Direct transfer of equine virus rather than reassortment
Spread within the canine population by dog to dog contact (droplets, aerosols)
Evidence for presence of influenza virus in subsequent outbreaks of non-fatal respiratory disease at race tracks and dog shelters across North America and a small numbers of UK reports in foxhounds
Vaccine now licensed in USA
H3N2 now likely endemic in US shelters
Serological studies in UK pet dogs so far negative
Canine distemper
Canine distemper virus (CDV), a morbillivirus (related to measles)
Shed in all body fluids
Spreads by aerosol or close contact
Nasal and ocular discharge, cough
Diarrhoea, vomiting
Depression
Anorexia
Virus enters via the respiratory tract
Spreads to tonsils and local lymph nodes
Infects monocytes/macrophages
Viraemia, systemic dissemination
2-3 weeks after infection dogs which are able to develop a good humoral and cellular immune response will recover or develop a mild form of the disease
In dogs with insufficient immune response CDV spreads to epithelial cells of the respiratory, gastrointestinal and genitourinary tract as well as the CNS
CDV causes immunosuppression secondary bacterial infections
Pasteurella multocida
LRT bacterial pathogens in dogs
Small Gram-negative rods (coccobacilli)
Main phenotypic traits:
Non-motile
Facultative anaerobe
Glucose fermentative
Oxidase-positive
Commensal of oral cavity and URT
Opportunistic pathogen associated with:
Secondary URT infections (>pets)
Secondary LRT infections (>cattle)
Bite infections in pets and humans
Usually susceptible to penicillin
No effective vaccines
Streptococcus spp
LRT bacterial pathogens in dogs
Gram-positive cocci in chains
Main phenotypic traits:
Non-motile
Facultative anaerobe
Glucose fermentative
Catalase-negative
Commensal on respiratory mucosae
Two species associated with pets
S. equi subsp. zooepidemicus
S. canis
Opportunistic pathogens that cause suppurative infections, including outbreaks in kennels
Susceptible to penicillin
Pathology of P. multocida LRT infection
Severe suppurative pneumonia and pleuritis (pyothorax/empyaema)
Important in cats following bites or other infected wounds
Often part of mixed infections
S. equi subsp. zooepidemicus
Commensal in the URT of horses (mainly associated with abortion/low-grade URT dz)
In recent years increasingly reported in dogs
Between 2006-7 a pathologist in California reported on an outbreak involving over 1000 dogs in a single kennel. These dogs had either suffered from or died of haemorrhagic pneumonia caused by a single clone of S. zooepidemicus
Pyrexia, haemorrhagic nasal discharge and sudden death
PM: severe necro-haemorrhagic and fibrino-suppurative bronchopneumonia
(Pyo)Granulomatous thoracic infections in pets
Rare infections in dogs caused by Actinobacteria, a diverse group of Gram-positive bacteria that grow slowly and produce branching filaments. Two species involved:
Actinomycetes viscosus: commensal in oral cavity of dogs. It can cause chronic pyogranulomatous lesions on the pleura (often associated with pyothorax) or other organs (e.g. cutaneous forms after bite wounds). The main clinical sign is respiratory distress. Usually responsive to penicillin.
Nocardia spp. (e.g. N. asteroides): soil bacterium that cause thoracic as well as cutaneous and disseminated forms. The clinical picture is the same as for actinomycosis but the organism is acid-fast and resistant to penicillin due to the wax-like mycolic acids in the cell wall. Sulfa TMP is one of the antimicrobials indicated for treatment of nocardiosis
Copious red-brown exudate in pleural cavity
May become chronic with adhesion formation
Exudate contains ‘sulphur granules’
Aspergillosis in dogs
Disease caused by Aspergillus fumigatus, a fungus inhabiting soil and decomposing organic matter
Acquired by inhalation of spores
Two types of infections in dogs (other animals may also be affected):
Nasal aspergillosis: invasive sinusitis with persistent and profuse sanguino-purulent nasal discharge (usually unilateral).
Systemic aspergillosis: this form occurs in immunosuppressed animals and clinical signs depend on location of the pathogen. Treatment is difficult (bad prognosis).
Rapidly growing (2-3 days) on Sabouraud Dextrose agar (medium used for fungal culture, low pH (5.5) plus antibiotics to inhibit bacterial growth)
Nasal turbinates progressively destroyed by chronic (pyo)granulomatous (and eosinophilic) inflammation
There may be a yellow-green mycotic exudate in the caudal nasal cavity
Bovine-lungworm
Dictyocaulus viviparus
Life cycle:
4weeks ppp
The life cycle is similar to that of the gastrointestinal nematodes except that eggs, containing first-stage larvae (L1) are coughed up and swallowed and then hatch during passage through the digestive tract. The L1 present in freshly-voided faeces, are characteristically sluggish and their intestinal cells are filled with dark brown food granules. The pre-parasitic stages do not need to feed. Under optimal conditions the L3 stage is reached within 5-7 days, but this may take longer depending on the environmental conditions. The L3 leave the faecal pat to reach the herbage through their own movements or by airborne spread utilizing the fungus, Pilobolus.
After ingestion, L3 penetrate the intestinal mucosa and pass to the mesenteric lymph nodes where they moult. The L4 then travel via the lymph and blood to the lungs, and break out of the capillaries into the alveoli about one week after infection. These migrate up the lungs and moult to L5, becoming mature adults between three and four weeks after infection, when L1 can be detected in dung. The adults are found in the main stem bronchi and trachea.
Clinical signs:
Youngstock during their first grazing season on permanent or semi-permanent pastures, from late summer-early autumn.
Characterised by bronchitis and pneumonia
Deep husky cough, worse after exercise. Which varies with the severity of the infection.
Stand with head and neck outstretched ‘air hunger position’.
Respiratory rate >80 bpm.
Bright, alert and feeding, however lose condition rapidly.
Expiratory dyspneoa and death can occur in heavy infections where there is massive obstruction of the airways.
Auscultations: harsh inspiratory and expiratory noise. Moist rasps as fluid accumulated, loud breath sounds and crackles over the bronchial tree (ventral lung consolidation) crackles over the dorsal diaphragmatic lobe (dorsal interstitial emphysema).
Diagnosis:
History (movement, pastures), clinical signs, auscultation.
Baermann technique faecal test-confirms lungworm infestation (see L1). Not all animals will shed larvae if they are int eh early stages of disease whilst the worms are immature. So absence of L1 does not exclude parasitic bronchitis from a differential diagnosis list.
Bronchoalveolar lavage or sputum examination for eosinophils, eggs, larvae is a sensitive method of diagnosis.
Serological or bulk milk ELISA antibody test are available in some parts of the world, however bulk milk samples may have a low sensitivity.
Post mortem
Baermann and ELISA prone to false negatives! So always be mindful of the history and clinical signs
Gross pathology:
lesions: large, grey, depressed, wedge shaped areas of atelectasis present usually along the dorsocaudal aspect of the lungs.
Reginal lymph nodes enlarged.
On the cut surface: oedematous foam and mucus mixed with white, slender (up to 80mm long) nematodes in bronchi.
In the most severe cases, massive numbers of nematodes fill the entire bronchial tree.
Microscopically: parasite in bronchi are associated with excess mucus due to goblet cell hyperplasia, metaplasia of bronchial and bronchiolar epithlium, alveolar oedema, hyperplasia of BALT, hyperplasia of bronchiolar smooth muscle and a few eosinophilic granulomas around the eggs and dead larvae. These granulomas , grossly, are grey nodules (2-4mm) and may be confused with those caused by tuberculosis.
Reinfection syndrome with Dictyocaulus viviparus
is an acute allergic reaction (full aetiology unknown).
It occurs when previously sensitized/immune adult cattle are exposed to large numbers of larvae. Many larvae are killed on reaching the bronchioles by the animals immune response. A large larval challenge may induce a severe and often fatal immune-mediated hypersensitivity reaction.
Lesions are of a hypersensitivity pneumonia
Clinical signs of severe respiratory distress, expiratory dyspnoea, oral breathing, pneumonic emphysema and subcutaneously on the back.
Diagnosis: disease does not become patent as the parasite is killed in the lungs so there will be no larvae in the faeces (Baermann test not useful). Low/no antibody response (ELISA not useful either)
Gross lesions include diffuse interstitial pneumonia with severe alveolar and interstitial oedema and interlobular emphysema. The lungs are enlarged, pale, rubbery, with lesions most notable in the caudal lobes.
Microscopically, eosinophils and larvae are seen in exudate. The lesions are alveolar and interstitial oedema and emphasema, formation of hyaline membranes within alveoli and in those animals that survive for several days, hyperplasia of type II alveolar epithelial cells.
Dictyocaulus filaria
life cycles: similar to cattle. Direct life cycle, and the females are ovo-viviparous (the females lays eggs which contain mature larvae).
clinical signs: usually non. Coughing and weigh loss in heavy infestations due to obstruction of the bronchi by adult worms, but very uncommon. Weight loss. May be severe when immune system compromised eg concurrent Johnes disease
diagnosis: Baermann test, Post mortem
Gross pathology : areas of atelectasis and pneumonia.
Microscopically characterized by a catarrhal, eosinophilic bronchitis with peribronchial lymphoid hyperplasia of type II pneumocytes and focal infiltration of lymphocytes and an alveolar exudate. Secondary bacterial pneumonia is common.
Muellerius capillaris ‘nodular lungworm’
Life cycle: requires slugs or snails as intermediate hosts
parasite infects a snail or slug intermediate host.
snail or slug is subsequently ingested by a sheep or goat while grazing.
larvae migrate to the lungs by the lymphatic system and cross into the alveoli or bronchioles.[1][5]
In the alveoli, the larvae mature to the adult stage, and the adults lay their eggs in the lung tissue.
The eggs rapidly hatch, and the larvae are coughed up or swallowed.[5]
The larvae are expelled into the environment in the sputum or feces.[5]
The larvae reinfect a snail or slug to complete the life cycle.
Clinical signs: usually non
Diagnosis: Baermann test, Post mortem
Gross pathololgy: multifocal, subpleural nodules, found mostly in the dorsal areas of the caudal lobes. The nodules are soft and haemorrhagic in the early stages, but later become grey-green and hard or calcified.
Microscopically, a focal eosinophilic and granulomatous reaction occurs in the subpleural alveoli where the adults, eggs and larvae reside.
Pigs-lungworm
Metastrongylus apri,
Metastrongylus edentates
Life cycles: requires an earth worm as an intermediate host. Therefore parasite only occurs where pigs have access to earth in an outside environment.
Worms found in the lungs 20-24days after the pig consumes the thick walled egg (contains L1 larvae).
Clinical signs: coughing and dyspnoea in young/growing pigs. (adults appear immune)
Diagnosis: clinical signs, history, management.
FWEC-thick walled eggs containing larvae
Gross pathology PM- adult worms are 45mm long, found in/squeezed out of bronchi or bronchioles of the diaphragmatic loves of the lungs. Pulmonary emphysema may be seen in caudal parts of the diaphragmatic lung lobes.
Ovine Pulmonary Adenomatosis (OPA)/ Jaagsiekte sheep retrovirus (JSRV)/ ovine pulmonary carcinoma
Sheep respiratory retroviruse
Highly transmissible, retroviral induced neoplasia of the lungs.
Clinically characterized by a long incubation period.
Spread by aerosolized respiratory droplets, and from ewe to lamb via milk or colostrum. Young lambs are most susceptible to JSRV infection and the time between infection and clinical signs developing (incubation time) is dependent on the age of sheep at infection and the dose of JSRV.
Found around the world, in particular in Scotland where there have been efforts to control its spread.
60 and 85 cases are diagnosed in veterinary labs in Scotland, England, and Wales per year, but this is certainly an underestimate
It is a neoplasm that presents as a pneumonia
Mainly affects mature sheep
Not naturally transmissible to goats
Affects mainly mature sheep, sometimes coughing and distress (particularly after exercise), lag behind the flock
Gradual loss of condition
10 to 40 ml per day of frothy, clear or at times pinkish fluid/mucus is common to pour from the nostrils but this can be up to 400 ml per day.
Around one third of cases don’t produce any fluid.
Normal appetite, normothermic
Death (after several months). Sometimes noticed as an increase in ‘sudden’ deaths
Cases peak in January and February due to affected sheep being unable to cope with adverse weather conditions and nutritional restrictions at that time of year.
Raise the pelvic limbs ‘wheelbarrow test’: copious, thin mucoid fluid, pours from the nostrils (not welfare friendly! Like drowning!)
Ultrasound examination of the lungs detects early disease (cull). only detect tumours over 1 cm in size in the ventral areas of the lungs. Therefore, it is not possible to guarantee absence of OPA in individual animals. any sheep with suspicious lesions at scanning are quarantined and scanned again 2 months later.
Post mortem (gold standard)
Histopathology
No commercial lab test for live animals-A PCR test has been used in research studies, but it lacks the sensitivity for field diagnosis in individual animals
Early: Lungs are enlarged, heavy, wet and fail to collapse. Contain several firm, grey, well demarcated variably sized nodules.
Later stages: nodules become confluent and large segments of both lungs are diffusely but not symmetrically, infiltrated by neoplastic cells.
On cross section, a copious mucoid secretion is in the airways
Sequalae includes: secondary bronchopneumonia, abscesses, fibrinous pleural adhesions, and metastasis occur to tracheobronchial and mediastinal lymph nodes, and to a lesser extent to the pleura, muscle, liver and kidneys.
Maedi –visna (MV)
Sheep respiratory retroviruse
Important, highly infectious, slow viral (lentivirus) disease in sheep
Maedi means ‘shortness of breath’ and Visna means ‘wasting or shrinking of the nervous system’ in Icelandic
It is sometimes referred to as lymphoid interstitial pneumonia
Caused by a non oncogenic retrovirus of the lentivirus subfamily
Seroepidemiological studies indicate that infection is widespread in the sheep population, yet clinical disease is rare.
The pathogenesis is not completely known. The transmission is thought to occur through ingestion of infected colostrum and milk, close contact and inhalation via droplets from the nose and mouth, cross contamination of blood from punches and needles
The virus remains for long periods of time in monocytes and macrophages. Clinical signs do not develop until an incubation period of over 2 years
Experimentally the incubation period can be reduced if lambs are inoculated intratracheally with ovine lentivirus in the perinatal period
Goats are considered to be susceptible: the same virus causes Caprine Arthritis Encephalitis (CAE) in goats and can be passed between the two species.
Impact on the flock MV has a long incubation period and the disease can spread unnoticed for many years before the signs are seen. By this time it is likely that at least half of the flock is infected resulting in high levels of culling.
The potential economic impacts are:
* 10-20% adult mortality after the development of clinical signs
* Lamb mortality and reduced growth rates due to lack of colostrum/milk
* A reduction in conception rates
* Increase in culling rate
An MV prevalence survey in 2013 found that in the 15 year period since the previous survey:
* The number of flocks with MV doubled (from 1.4% to 2.8%)
* The number of infected sheep increased almost four fold (2 per 1,000 to 8 per 1,000)
* Within affected flocks the average proportion of infected sheep almost doubled (13% to 24%)
Dyspnoea
Insidious slowly progressive emaciation despite good eating
Chronic mastitis
Progressive weakness leading to paralysis
Arthritis
Death (may take months)
Serological testing (screening packages and accredited free status available)
Post mortem
Severe interstitial pneumonia, lungs fail to collapse when thorax opened. Rib imprints on the lung surface
Lungs are pale, mottled and heavy (2-3 x normal). Regional lymph nodes enlarged.
Other pathology: encephalitis, non suppurative arthritis with periarticular fibrosis, lymphofollicular mastitis, or vasculitis
Combination of these lesions or remain infected but disease free for life
List some clinical signs and gross pathology associated with African swine fever
Pyrexia
Fever
Respiritory distress
Petechial haemorage
Sudden death
Vomiting
Cutaneous erythema
Enlarged friable spleen
Haemorages in lymphnodes- Gastohepatic lympnode specifically
Haemorage in kidneys
Oedema of gall blader
Perirenal oedema
A dog presents with a haemoabdomen and a focal splenic mass is found. Histopathology reveals a pleomorphic and anaplastic mass with features of malignancy. What would be the next most appropriate test to request of the pathologist to confirm the diagnosis?
immunohistocheistry- Good for determining tumour type
Electron microscopy could be helpful but is not appropriate outside of a research project
A dog presents with haematuria. Urinary sediment examination revealsc occi bacteria phagocytosed in neutrophils, normal epithelial cells and struvite
What is the next best test?
Struvite is more likely in bacterial infections
The bacteria have been phagocytosed so it is usually they are a result of contamination and it is a true bacterial infection
Bacterial urine culture is next best step
A cat presents with weight loss despite polyphagia and a unilateral goitre is palpated. Biochemistry reveals mildly increased ALT. What is the confirmatory test?
Serum total thyroxine (T) 4 levels
it is a clinical sign of hyperthyridism
serum iodine is more a concern in farm animals
dog is reported to be lethargic and polydipsic and polyuric (PUPD). It has a pot belly and fur loss What are the top two differentials?
Hyperadrenocotisism
Hyperthyroidism
Diabetes melatus would be a ifferentail for pupd but coat condition is not caused by this
A post mortem is performed on an aborted foal. It is jaundiced with Random hepatocellular necrosis. What is the key diagnostic finding on histopathology in this case?
Intranuclear inclusion bodies
Name the syndrome and suggest a cause for mumification of a litter of pigs
SMEDI- stillbirth, mumification, embryoinic death, infertility
Porcine parvo virus
Which additional histochemical stain will highlight the aetiological agent in jhones disease
Zheil neilson
A dog presents with chronic diarrhoea and weight loss. On a blood test it has slightly low calcium, low total protein, cholesterol, albumin, globulin and ag ration. What test would you perform next?
Urea and createnine ok and so kidneys ok
Liver markers are ok so liver ok
Intestinal biopsy would be most useful- inflammatory bowl disease, lymphoma
A horse presents with photosensitisation (severe sunburn and hairloss)- Which internal organ is primarily affected if this horse is also presenting with neurological signs?
liver
Hepaticecepalopathy- build up of amonia
Liver damage in horses is associated with whicbh plant
ragwort
A previously obese cat presents with weight loss and PUPD. Biochemistry reveals increased glucose. Urinalysis (DipStick) reveals ketonuria. What test next?
Fructosamine test
A horse with sudden lameness following a wound to the limb and a hot swollen joint undergoes arthrocentesis revealing high numbers of neutrophils and xoxxi bacteria phagocytosed within. Formulate a morphological diagnosis and what test are you doing next?
Suprative arthritis
Culture
Describe the clinical signs and explain the pathogenesis of Horner’s syndrome in horses.
Facial nerve paralysis
mydriasis
could be due to guteral pouch disease or neck injury
A Doberman dog breeder would like to screen their pack for heart disease. Which clinicopathological test would be most useful?
NT-proBNP
Reportable diseases in birds
Salmonella- all birds
Chlamydia psittiaci- in chicken turkeys and parrots
Avian mycoplasmosis
Mycoplasma gallisepticum
& Mycoplasma meleagridids- in chicken and turkey
Salmonella in pheasants
whiote discolouration in caeca- ceacal cores
would be cultured and reported if pathegen found
game birds often carry salmonella and so bacteriology must always be done in liver
Mycoplasmosis in pheasants
presents with swolen head
sparce fetheratin around eye- swelling increases distance in feahers, closed eye
exudate in nasal cavity
Notifiable diseases in bird
Avian influenza
newcastle disease
west Nile Virus- not currently in uk but birds are being screened
Clinical signs of
notifiable diseases in pheasants
- Mortality- most important
- Neurological signs
- Intestinal signs
Avian influenza: post mortem findings
Pancreatic necrosis
splenic necrosis
Pulmonary congestion and
pneumonia
Hydropericardium
but sometimes there is nothing to see- very acute disease
how to test for spironucleus in phesents
wet smears done at post mortem in recently euthanised animal from mid-intestine and caeca
choanal groove
an opening between the nasal and oral cavity in birds
good place for swab sampling for PCR
Avain influenza
5-75% mortality in chickens
100% in turkeys
As low as 0% in ducks
Incubation of 3 to 10 days
Winter virus
Current strain is H5N1 (hemagglutinin type 5 and neuraminidase type 1)
influenza virus
Waterfowl/shorebirds, poultry, mammals
Anseriformes/Charadriiformes (natural reservoir hosts)-
Asymptomatic carrier species (i.e. mallards)
Sentinel species (i.e. swans)
Non waterfowl species (i.e. ostriches, falcons)
High mortality in farmed poultry (chickens and turkeys)
Variable morbidity and mortality in wild birds
Influenza A virus - Orthomyxoviridae - RNA virus
Subtypes: antigenic variation in haemagglutinin (HA, 16 subtypes) and neuraminidase (NA, 9 subtypes) glycoproteins
Low pathogenic and highly pathogenic strains
Based on experimental poultry infections
LPAI - typically wild birds
HPAI - poultry with spill over to wild birds
LPAI - prevalence peaks in late summer and early winter
Species and location dependent
HPAI - often associated with autumn migration
Acute infection (~4-8 days) ends with an immune response or death
Variable clinical signs
LPAI - subclinical
HPAI - lethargy, respiratory and neurological signs
Macroscopic Findings:
Emaciation and muscle wastage (juveniles)
PANCREATIC HAEMORRHAGE AND NECROSIS
Duodenal, myocardial and air sac haemorrhages
Pulmonary congestion, oedema and consolidation
Hepatosplenomegaly
Histopathological Findings:
Necrotising pancreatitis and hepatitis
Lymphoplasmacytic encephalitis with neuronal necrosis and neuronophagia
Confirmation of infection-
Virus isolation (PCR)
Demonstrating viral nucleic acid or antigen in tissues (IHC) (Fig 3D)
Newcastle disease
Paramyxovirus
Affects- respiratory system (mainly respiratory disease)
Intestinal system
Neurological system
Labored breathing
Head shaking
“snicking”- birds cannot cough or sneeze due to no diaphragm so headshake to expel air fro respiratory tract
Lesions in gizzard- hemorrhagic lesions in gastric glands (not pathognomonic)
Green scour
Torticollis- twisting of neck, stargazing ect
Ataxia
Can vaccinate against it and routinely do- live and attenuated vaccines
Vaccines administered to chicks on raring farm- primed with live and boosted with dead vaccines
Aspergillosis in birds
Cotton like lesion in airsacks
Labored breathing
Abdominal breathing
Typically in game birds
Typically don’t die but do show signs
Comes in on wet bedding and straw so is seen in birds housed on straw
Gape worm
Syngamus trachea
Seen often in game birds- disease of stocking density
Found in trachea- male and female attached toghther and consume blood form the trachel wall which they are attached to
Bird cough up eggs they are producing and swallow them
Birds will “gape”
Lifecycle 3 weeks
Use anthelminthic- worm every 3 weeks- meat withdrawal 8 days at longest. Not given medicine at point of release with game birds
Without treatment the worms will eventually block windpipe
Sour crop
Fungal infection of crop
Older birds crops sag and food sits at the bottom of crop and ferments
Diseases of upper gi tract in bird
Tvp- transmissible viral proventriculitis- effects ability of gastric glands and lining of gizzard
Mechanical damage of gizzard- nails, wires, large grit, failure pf coilus (protective barrier)
Merkles diverticulum
Exact landmark between jejunum and illium
Reminanat of yolk sack- residual scar tissue
Omphalophlebitis
inflammation and/or infection of the umbilical vein
typhlitis
inflammation of the caeca
often protozoal disease
typhlitis
Cocsidiosis in chickens
Motile protzoal disease
Not same presentation in different birds- different species, species specific, no cross infection
Chickens- affected by several species in the Eimeria family:
In duodenal loop you can see white scars with Eimeria. Acervuline (a comes first)- Lifecycle- 7-8 days: after 3 cycles chicken often cannot cope
Red dots all along the intestinal tract are indicative of Eimeria. Maxima- the oocyst is largest microscopically (effects large amount of tract)- chicken most effected after 4 lifecycles, day 21
Heamorage of the caeca is a typical presentation of Eimeria. Tenella
Alphabetical order of portion of tract they effect: AMT
Eimeria. Brunetti (b for bum) effects colon
Eimeria. Necatrix- seen in all of digestive tract, though not often not caeca
Biggest economical cost to broiler industry
Biggest economical cost to broiler industry
All linked to necrotic enteritis
marek’s disease
(‘MD’ or ‘fowl paralysis’) is a very common disease of chickens caused by a herpes virus
Infected for life
Virus becomes dormant in nervous tissue
Clinical singns- nervous
Legs splayed out- completely ataxic
Torticollis
Transient paralysis
Often infects younger bird- fliars up at point of stress like lay
Commercial long living birds (breeders and layers) routinely vaccinated but broilers are not- inactivated virus
No treatment
Sample sites are sciatic nerve- infected nerve much larger
Feather follicle- virus sheds in dander and so can be found
Can live in environment for 20 years or more
Isospora in birds
Formerly Atoxoplasma
Protozoan parasite- Obligate intracellular coccidian
Enteric form-
present Throughout birds
Intestinal form
Oocysts shed in faeces
Diarrhoea and weight loss
Systemic Isosporiasis-
Restricted to the order Passeriformes
Extraintestinal/visceral form
Clinical significance and pathogenicity questionable
Often subclinical
Morbidity and mortality uncommon
Restricted to fledglings exposed to high parasite loads or stress-induced reduction in immunity associated with overcrowding / co-morbidities
Gold standard: direct visualisation of asexual merozoites within circulating mononuclear cells
Buffy coat or impression smears
Difficult ante-mortem
Blood sampling challenging, visceral impressions PM
qPCR for pooled faecal samples
Post Mortem Examination less sensitive
Macroscopic findings
Often unremarkable
Splenomegaly and hepatomegaly
Histology used to assess host response instead of detection
Lymphocytic, lymphohistiocytic or lymphoproliferative splenitis and hepatitis
Widespread dissemination in severe cases
Neoplastic transformation rarely reported
can see Intracytoplasmic merozoites within a parasitophorous vacuole that peripheralise and indent the nucleus
Trichomonosis in birds
Trichomonas gallinae
Flagellated protozoan parasite- Most species are commensals of the GIT
Pigeons (canker) - primary carriers
Birds of prey (frounce) - feeding on infected birds
Gardens birds (finches in particular) - UK epidemic in 2006-2007
Transmission via contaminated food or water
Clinical signs: lethargy, fluffed up plumage, dysphagia, dyspnoea
Predispose to aspiration pneumonia
Concurrent fungal (Candida) or bacterial (S. aureus) infections are common
Diagnosis- Identification of motile flagellates on a wet mount
Culture or PCR from swabs/tissues
Organisms are round to ovoid, ~ 5–7 µm in diameter with a small condensed nucleus
Macroscopic findings
Yellow mucosal plaques - oropharynx, oesophagus, crop
Lesions extend into the subjacent soft tissues, bone and nasal cavity
Histology findings-
Fibrinoheterophilic and necrotising (diphtheritic) inflammation
Stomatitis, oesophagitis, ingluvitis
+/- flagellates at the leading edge
Salmonellosis in birds
Salmonella enterica serovar Typhimurium
Songbird salmonellosis – passerines- Seed eating birds: greenfinches, house sparrows
Can also affect waterfowl and shorebirds
Outbreaks more common in cold months or during migration
Can be associated with crowding at feeders - faecal oral transmission
Clinical signs:
Found dead
Non-specific signs: lethargy, fluffed plumage, weight loss
Pasting of faeces at the vent
Diagnosis:
Bacterial culture - crop/oesophagus or in multiple organs in disseminated cases (septicaemia)
Macroscopic findings
Acute: pinpoint white lesions in the liver and spleen
Chronic: multifocal caseous nodules / necrotising ingluvitis and oesophagitis
Histology findings-
Foci of necrosis - crop, oesophagus or multiorgan necrosis (liver, spleen etc.)
Infiltrating heterophils and macrophages (Fig 7) with intra- and extracellular gram-negative bacilli (arrows)
Incidence and prevalence are currently low compared to 2000s
Prevention and control - hygiene (can persist in the environment)
Zoonotic risk (very low compared to other causes of salmonellosis in humans)
Avian Poxvirus
Poxviruses - Avipoxviruses - large, enveloped DNA virus
Affects a wide variety of bird species globally (different strains)- UK - great tits most frequently affected
Transmission via direct contact, fomites or biting insects (mosquitos)
Cutaneous or diphtheric forms - Cutaneous more common in passerines
Macroscopic findings
Wart-like growths on non-feathered skin (feet, digits, cere, periorbital)
Histologic findings- Epithelial hyperplasia (epidermis and follicles)
Swollen epithelial cells with cytoplasmic vacuoles/oedema (ballooning degeneration)
Few to numerous variably sized (often large) eosinophilic, intracytoplasmic inclusion bodies (Bollinger bodies)
Lesions can be self-limiting and regress spontaneously over weeks
Can affect vision, feeding and perching- Trauma, emaciation
Opportunistic bacterial and fungal infections- Contribute to morbidity and mortality
Finch Leg Abnormalities
Papillomaviridae - Papillomatosis - tassel foot
Fringilla coelebs papillomavirus (FcPV1)
Epitheliotropic double-stranded DNA virus - host specific
Cnemidocoptes - Cnemidocoptosis - mange / scaley leg
C. jamaicensis and C. intermedius - affect 10 species of European finches
Burrowing mite
Chaffinches most common; rarely brambling, bullfinch and greenfinch
Transmission via contact
Mixed infections are common
Minimal clinical significance - low mortality
Macroscopic findings - Proliferative leg lesions (FcPV1 & Cnemidocoptosis)
Unilateral or bilateral
(Squamous) papillomas and wart-like growths
Nodular or hyperplastic lesions with deeply fissured papillary growths (i.e. papilliferous)
Grey/white diffuse scale, “powdery” to severe hyperkeratosis with crusts and scabs
Histologic findings - Proliferative leg lesions (FcPV1 & Cnemidocoptosis)
Epidermal hyperplasia, papillary projections, hyperkeratosis, keratinocyte vacuolation, acanthosis
FcPV1 - Intranuclear inclusion bodies
Cnemidocoptosis - Sections through mites
Diagnostic Tests - Proliferative leg lesions (FcPV1 & Cnemidocoptosis)
Histology
FcPV1 - PCR
Cnemidocoptosis - NaOH digest of skin lesions
pathological findings of trauma in wild birds
Common in all wildlife species
Accidental (i.e. window strike)
Secondary to a primary disease process (i.e. falling from a perch due to poxvirus/FcPV2/Cnemidocoptosis lesions)
Iatrogenic (i.e. traps, firearms, fencing)
Predation (i.e. domestic cats)
Haemorrhage - subcutaneous, coelomic
Fractures - appendicular skeleton, cranium, beak
Anaemia and Neurological deficits
Limb amputation-
Traps
Accidental collisions with fences
Feline herpesvirus
Key points
The domestic cat is the main host althoughother felids can be infected
Prevalence high; large populations,shelters
Acute upper respiratory andocular disease, particularly severe inyoung kittens
Almost all cats undergo a latent infection, whichcan lead to recurrent clinical signs, mainly ocular diseases (conjunctivitis andkeratitis) afterintermittent reactivation
The virus enters the body via the nasal, oral orconjunctival routes.
Acute disease usually resolves within 10 to 14 days althoughocular signs, incases of keratitis, can persist longer. Some animals develop chronic lesions inthe upper respiratory tract andinocular tissues.
Following infection, the virus spreads along the sensory nerves andreaches the neurons, particularly inthe trigeminal ganglia. It is thought thatall cats experiencing primary infection are likely to become lifelong latent carriers.
CLASSICAL ACUTE-
Rhinitis, conjunctivitis, tracheitis
Corneal ulcers*
Sneezing, nasal discharge, salivation, coughing, conjunctival hyperaemia andserous ocular discharge
ATYPICAL ACUTE-
Peri-ocular and facial dermatitis
Viraemia, pneumonia
Nasal andfacial ulcerated andcrust-forming lesions
Severe systemic signs, coughing, death (acute death inkittens, “fading kitten syndrome”)
CHRONIC -
Stromal keratitis
Chronic rhinosinusitis*
Corneal oedema, vascularisation, blindness
Chronic sneezing andnasal discharge
Feline calicivirus
Key points
Highly contagious, widespread distribution
No known reservoirs oralternative hosts
A single diverse genogroup
Infected via the nasal, oral orconjunctival routes
Prevalence is broadly proportional to the number of cats ina household
High FCV prevalence within a colony is associated with high FCV strain diversity
Cats can be infected with FCV via the nasal, oral orconjunctival routes.
Acute oral and URT disease – ulcerative lesions on tongue
Acute mild respiratory disease
Pneumonia – young kittens
Feline chronic gingivostomatitis??
Limping syndrome
FCV less commonly affects other tissues, such asthe lungs, leading to pneumonia
Co-infections of feline herpesvirus (FHV) andFCV are generally very common andhave been described inkittens with pneumonia; FHV infection leads to airway damage, whichmight facilitate secondary infection with FCV due to reduced mucociliary clearance andimpaired immune defences
Acute synovitis with thickening of synovial membranes andincreased synovial fluid have been noted incats with limping kitten syndrome
Limping kitten syndrome can also occur afterFCV vaccination with some modified live virus vaccines.
Virulent Systemic - calicivirus
VS-FCV strains cause:
widespread vasculitis
multi-organ involvement
very high mortality
CASE: Severe respiratory disease in a large colony of farm cats
High morbidity and mortality, no URT
Tachypnoea progressing to dyspnoea
Different cell tropism-
ulcerative skin lesion in cats
Feline allergic miliary dermatitis
Feline mosquito bite sensitivity
Feline herpesviral ulcerative dermatitis
Feline cowpox viral infection
Feline indolent ulcer (Eosinophilic Granuloma Complex)
Feline idiopathic ulcerative dermatosis
(underlying abscess, neoplasia, trauma etc)
Feline cowpox
Key points
Orthopoxvirususually cowpox virus
Wide host spectrum including man zoonosis!
Rodent contact
Skin lesions predominantly onthe head andpaws
Usually heal spontaneously, insevere cases progressive proliferative ulcerations ensue
Inkittens andimmunosuppressed cats, generalized cowpox infections frequently take a fatal course
Corticosteroids enhance systemic spread of the virus andare contraindicated
enters via bitewound from rodent
Potential ZOONOSIS
If immunosuppressed (FeLV/FIV) or treated with steroids:
necrotising pneumonia,
nasal discharge, diarrhoea, death
– don’t give them steroids!!!
Oval to circular ulcerated papules and plaques with crusting
Diagnostic tests – on the scab
PCR***
Serology for Ab titre
Ddx: Tongue lesions in cats
Trauma
Neoplasia (SCC**, sarcoma)
Eosinophilic granuloma complex lesion
Ulcerative glossitis as part of a more generalised stomatitis, a common condition especially of older cats; multifactorial:
imbalance in oral microbial flora
feline calicivirus
feline herpesvirus 1
possibly an immune-mediated component?
A more generalised underlying condition, for example uraemia
Papillomavirus lesions – plaques, feline “sarcoid” – fibropapilloma
The Top 4 of Feline Skin tumours
- Basal cell tumours 22.6%
- Fibrosarcoma 19.5%
- Squamous cell carcinoma 11.4%
- Mast cell tumour 6.8%
Basal cell tumours in cats
Actually a group of tumours, all composed of basal cells
Can be grossly cystic and/or pigmented (ddx melanoma)
The two most common types in cats include:
Apocrine ductal adenoma
Trichoblastoma (hair follicle origin)
Not always sub-classified
BENIGN
Soft tissue sarcoma (fibrosarcoma) in cats
Second most common
Including FISS**
Most (but not all) considered low to intermediate malignancy
Infiltrative and often locally recurrent
Metastasis is uncommon
Grading system proposed
Surgical excision = treatment of choice
Feline Injection Site Sarcoma
Often but not always fibrosarcoma
More aggressive, larger, younger cats
Highly recurrent
Metastatic potential
Anatomical location
Infiltrative behaviour
Pleomorphism
Lymphocytic infiltrates
Macrophages with intracytoplasmic pigment (adjuvant)
A compatible history
Mycobacteriosis
Approx. 1%
Cutaneous/subcut nodules
Abscesses which do not heal or are only partially responsive to AB
S.W., S.E. of London, N. England or S. Scotland
Potential zoonosis
Histopath = first line of diagnosis
If you suspect Mycobacteriosis, say so on the form so the pathologist can request a ZN stain
Diagnostic if acid-fast organisms are seen
But not necessarily excluded if negative
Histopath cannot speciate
Culture of fresh or frozen tissue (50%, can be very slow)
IFNg release assay (blood test) 70-100% sensitive
PCR based; fresh preferred, can use formalin-fixed
Other presentations:
GIT – mass lesion – outbreak associated with raw feeding
Ocular lesions
Cryptococcus neoformans in cats
More common feline fungal rhinitis
Can also present as cutaneous lesions
Opportunistic pathogen
Coexistent debilitating disease / immunosuppressive diseases
Potentially zoonotic
Saprophyte organism
Soil contaminated with pigeon excrement
Most common systemic fungal infection of cats
Multiple organs may be involved; respiratory tract disease, subcutaneous nodules, lymphadenopathy, intraocular inflammation, fever, or central nervous system (CNS) diseases
always advise identification either by culture or PCR testing, prior to deciding on treatments
Cerebral cryptococcosis with so-called “Soap bubble” lesions (pathognomonic)
Fungal diseases presentations in cats
Dermatophytosis aka “Ringworm”
Culture advised
Systemic therapy is the treatment of choice
Can be difficult to eradicate
Asymptomatic carriers
Potential zoonosis, especially in
immuno-compromised individuals
Microsporidium canin (natural host is cat not dog), Trichophyton mentagrophytes and M. gypseum are the most common isolates.
Culture is advised in these cases to determine which species is involved since this may affect client advice and treatment regime. In general terms, systemic therapy is the treatment of choice, but this can be a difficult condition to eradicate successfully, especially in multi-cat households, where asymptomatic carriers may perpetuate the condition. Be aware that this is a potential zoonosis, especially in immuno-compromised individuals.
Masses caused by fluid in cats
Abdominal – Thoracic – Bicavitary - Pericardial
FIP (“wet form”)
Cardiac causes
Liver disease
Hypoproteinaemia
Purulent - peritonitis
Neoplastic – abdominal tumours - mesothelioma
Haemorrhage – amyloidosis liver
Urine – ruptured bladder
FIP
Key points
Feline coronavirus (FCoV) is ubiquitous
Most FCoV-infected cats either stay healthy orshow only mild enteritis
Only a small proportion of FCoV-infected cats goes onto develop feline infectious peritonitis (FIP)
FCoV transmission is faecal-oral via litter trays andfomites
FCoV infection of monocytes is the key event inFIP pathogenesis
Internal mutation theory = internal mutations of FCoV
= switch of cell tropism arising inan individual cat
= development of highly pathogenic FIP-inducing FCoV
Pedigree cats, under two years old
Sample the effusion
GOLD STANDARD diagnosis of FIP = histopathological changes + FCoV antigen IHC
Positive FCoV antibody is not confirmatory of FIP
Absence of FCoV antibodies makes FIP less likely.
Coronaviral genomes possess a high level of genetic variation due to the error rate of RNA polymerase leading to different types of mutations.
FCoV infection occurs following ingestion of the virus (e.g. by grooming paws contaminated with faeces during litter tray use)
FCoV then replicates inthe epithelial cells of the small intestinal villi, resulting infaecal shedding within a week
enteric FCoV infection is often asymptomatic butcan result inenteritis
FCoV is then found inthe colon wherethe main site of viral replication is the ileo-caecocolic junction.
FCoV infection can then spread to the mesenteric lymph nodes followed by viraemia inthe blood.
low level FCoV viraemia inmonocytes can occur incats thatdo not go onto develop FIP
Immune response can clear the infection at these stages still, even with low level viraemia
efficient andhigh FCoV replication inactivated monocytes andmacrophages (which are likely mediated by viral mutations) is believed to be a key event inFIP pathogenesis, alongside the nature of the immune response mounted by the cat inresponse to FCoV infection.
WhenFIP develops there is a reaction between replicating FCoV inmonocytes andblood vessel walls, allowing extravasation of the monocytes, wherethey differentiate into macrophages. Breakdown of the endothelial tight junctions
Virus survives and replicates in large numbers
= HIGH VIRAL LOAD
Virus replicates within monocytes and macrophages
Activated = VASCULITIS** and PERIVASCULITIS
Breakdown of endothelial tight = junctions plasma leaks out
Effusion inthe abdominal, thoracic and/or pericardial cavities
WET FORM
Often fast developing
Larger perivascular pyogranulomata
More chronic – DRY FORM
Mass lesions
Signs depend on vessel location:
Liver
Lungs
Kidneys
Brain
Intestines
EYES**
Liver with fibrin deposition
over the capsular surface
cerebrum, with dilated lateral ventricles (hydrocephalus)
Granulomatous inflammation obstructing CSF outflow at level of mesencephalic aqueduct
“Dry” FIP often has ocular changes, such as uveitis, hypopyon, vasculitis
History suggestive?
lymphopaenia
non-regenerative anaemia
increased TP, hypergammaglobulinaemia, low alb/glob ratio
high a1 acid glycoprotein and high FCoV titres
Effusions:
positive Rivalta’s test
high protein
low alb/glob ratio
neutrophils and macrophages
typically straw coloured, clear and non-odourous
Biopsy – typical lesions and positive staining cells by immunofluorescence/IHC currently gold standard
RT-PCR
Cardiac disease in cats
As a cause of sudden unexplained death?
Initial differential list:
Cardiac disease
asymptomatic cardiomyopathy (HCM, ARVC)
less likely valvular disease (endocarditis)
pericardial disease
neoplasia (lymphoma, heart base mass)
congenital heart defect
Trauma
Pre-existing disease (non-cardiac)
Toxin exposure (malicious or accidental)
Cardiomyopathy in cats
Cardiomyopathy
HCM (LVOTO, ES-HCM); 1° vs 2°
DCM (taurine)
ARVC
UCM
Hypertrophic cardiomyopathy (HCM) most common form
15% of the domestic cat population, primarily as subclinical disease
severe HCM leading to heart failure or arterial thromboembolism (ATE) only occurs in a small proportion of these cats
a genetic cause of HCM has been identified in two breeds and is suspected in another, but for most cats the cause is unknown.
Dxx for palpable abdominal mass in cats
Gastrointestinal;
Neoplastic (lymphoma, mast cell tumour, carcinoma, sarcoma/GIST)
FIP
Fungal granuloma
Feline Gastrointestinal Eosinophilic Sclerosing Fibroplasia
Mycobacteria
Other sites; splenic, hepatic, lymph nodes, pancreas, bladder, kidneys, adrenal glands
Lymphoma in cats
most commonly diagnosed neoplasm in cats
presents in various forms and clinical signs, depending on the organs / site(s) affected
There are various ways of classifying lymphoma in cats:
Phenotype
Anatomical site
Viral versus non-viral related
Anatomical site
lack of consensus between studies
primary lymphomas with nodal involvement
Broadly classified into four anatomical groups:
Multicentric
Mediastinal/thymic (confined to the thoracic cavity)
Alimentary (sometimes includes renal and hepatic)
“Extra-nodal”
Anatomical site: extra-nodal, non-GI lymphomas
NASAL/Upper Respiratory Tract
pharynx, larynx and trachea as well?
vast majority of nasal lymphomas = B-cell origin
appears to carry the best prognosis
OCULAR
uncommon site
unilateral or bilateral
often present in multicentric forms
may affect the uvea, the cornea, rarely the retina
may also involve the retrobulbar space = exophthalmos
RENAL
older cats (not always)
often if not always bilateral
often presents with involvement of other organs (but not always)
majority = B-cell origin
CNS
Traditionally the most common spinal tumour in cats; FeLV?
can also be present as an intracranial mass
often involvement of other organs; spinal and renal lymphoma
lowest response rate
Feline gastrointestinal lymphoma
Mucosal only – T-cell
Most common form
Diffuse
Difficult to distinguish from diffuse lymphocytic enteritis
MST = 29 months
Low grade
Transmural – T-cell or B-cell
B-cell transmural lymphomas stomach, jejunum, ileo-caecal-colic junction
Presents as a mass
MST = 1.5 months for T-cell
MST = 3.5 months for B-cell
Intermediate or high grade
Viral verses non-viral related, i.e. whether or not the tumour is associated with infection with FeLV and/or less commonly FIV.
Viral related:
Younger cats
Certain anatomical sites
multicentric
mediastinal/thymic
possibly the CNS.
As vaccination against FeLV has become more widespread, the relative numbers of these types of lymphoma have declined, changing the pattern of disease we see clinically and diagnostically.
FeLV
Retrovirus, prevalence in Europe generally low – vaccination
Infection normally via saliva (grooming, shared bowls, bites)
Does not survive long outside the host
Viral RNA →
→ reverse transcription →
→ viral DNA →
→ usually incorporated into
host genome ( = provirus)
Diagnostic tests
FeLV p27 antigen (in house) – detects Ag in circulation
FeLV provirus – detects genome integrated FeLV proviral DNA
FeLV RNA – detects RNA in circulation
BEWARD FALSE POSITIVES in FeLV p27 antigen test in areas of low prevalence
ABORTIVE INFECTION-
Circulating anti-FeLV antibodies
Infection not detectable
(negative on p27 Ag and PCR)
REGRESSIVE INFECTION
Proviral DNA remains in DNA of host cells (DNA PCR positive)
Cat has overcome viraemia / no viraemia (p27 Ag negative)
Viraemia can be reactivated
PROGRESSIVE INFECTION
Viraemia persists
Shedding FeLV
Often develop FeLV associated diseases
(positive on p27 Ag and DNA PCR)
Clinical signs in persistently FeLV viraemic cats
Anaemia (mostly non-regenerative)
Immune suppression
Lymphoma (mediastinal, peripheral, spinal)
Less common:
Other lymphoma, other neoplasia, immune-mediated uveitis, reproductive,
peripheral neuropathies
FIV
Retrovirus, closely related to HIV
Endemic; seroprevalence varies between regions
Most infections acquired by bites (fights, mating) from persistently infected cats
Long asymptomatic phase (years, some never develop disease
Clinical signs – immunodeficiency causes….
Chronic gingivostomatitis
Lymphadenopathy
Chronic rhinitis
Weight loss
Renal failure (immune mediated glomerulonephritis)
(neoplasia, incl lymphoma/leukaemia, bone marrow disease, neurological signs)
Feline Gastrointestinal Eosinophilic Sclerosing Fibroplasia
Middle aged cats
Ragdolls
Long histories!
Palpable mass, hard
Pylorus and ICC often
Lymph node involvement
Cause????
Thyroid disease in cats
Hyperthyroidism – functional hyperplasia / adenoma
Progresses over time to well-differentiated carcinoma?
Often bilateral
Beware hypocalcaemia in bilateral thyroidectomies
Beware ectopic thyroid tissue!
Toe leasions in cats
Lung-digit syndrome
Fungal / bacterial infection
PF
Giant cell granuloma
Lung-digit syndrome
Primary lung neoplasia metastases to digits
It’s a cat thing!
Giant cell granuloma
Lump on cat toe close to nail bed
Multinucliated giant cells
Mitotically active spindle cell populations
Not really turmours- reactive change in nail bed
Not malignant
Can also see in mouth
Feline Parvovirus
SNAP test
Loss of crypts in intestinal histology
Knocks out eplicating crypt epithelial cells- can no longer produce intestinal epithelium
Remianing epithelial cells become flattened and elongated or hyperplastic to compensate
High mortality rate particularly in kittens
Enteritis
dhiarea
High mortality (more than 90% in kittens)
Diagnostic tests
Faecal testing for FPV antigen (PCR on whole blood, faeces)
IHC available
Basophilic IN inclusions in enterocytes, lymphocytes (early)
Diseases it causes include (targets replicating cells)
Diarrhoea, enteritis
Lymphopaenia, neutropaenia, thrombocytopaenia and anaemia
Cerebellar ataxia (kittens)
Abortion
Toxoplasmosis in cats
Liver: hepatic necrosis
Lung: interstitial pneumonia
Heart: necrotizing myocarditis
IHC confirmed Toxoplasmosis gondii
Systemic Toxoplasmosis-
Cats = definitive host of Toxoplasma gondii
Organism can infect a wide variety of species (birds, rodents, herbivores, carnivores) which may act as intermediate hosts.
Infection widespread in most domestic animals (and humans)
Overt disease is rare except as a cause of abortion in sheep and goats
(and, rarely, transplacental infection in humans)
Systemic toxoplasmosis occurs most commonly in young or immunocompromised animals and corticosteroids, ‘stress’ or infection with immunosuppressive viruses (e.g. FeLV/FIV in cats) may exacerbate disease or reactivate a latent infection.
IMPORTANT NOTE: THIS INFECTION HAS ZOONOTIC POTENTIAL
canine distemper in ferrets
Serious disease, essentially 100% fatal
Morbillivirus (causes canine distemper) accelerated syndrome in ferrets
Disease progression:
12 days in ferret-adapted strains
42 days in wild canine strains
Profoundly immunosuppressive
animals that survive this stage succumb to neurologic dysfunction within several weeks
Gross lesions similar to those seen in the dog:
Photophobia
Oculo-nasal discharge
Hyperkeratosis of the planum nasale and footpads
Papular rash
Bronchopneumonia
Non-suppurative encephalitis with
demyelination = neurologic disease
FIP??? in ferets
2006 – novel granulomatous disease in ferrets resembling the dry form of FIP
Ferret coronavirus known to cause epizootic catarrhal enteritis
Gross lesions resemble dry form of FIP (systemic form)
Granulomas - mesentery, abdominal and less commonly thoracic organs
Affected animals may show:
mild anaemia, thrombocytopaenia, hypergammaglobulinaemia
Epizootic catarrhal enteritis
= coronaviral disease of ferrets, epizootics of high morbidity (up to 100%), but low mortality
Ferret enteric coronavirus (FECV)
diarrhoea - rapidly dehydrating and most mortalities occur in older animals with concurrent illness
vomiting
dark green stool with abundant mucus
Influenza in ferrets
only domestic animal species susceptible to human influenza viruses
often infected by their human owners
clinical signs:
photophobia
catarrhal nasal discharge
sneezing, coughing, pyrexia
anorexia, and malaise
Aleutian disease
ferrets
caused by a parvovirus
In mink: rapidly life-threatening immune-mediated glomerulonephritis, vasculitis and hypergammaglobulinaemia
In ferrets: notable similarities, including hypergammaglobulinaemia, immune complex glomerulonephritis (later stages)
In ferrets, the disease is much more insidious, with progression as long as 2 years
Ferrets in the late stages of disease will be hyperproteinaemic
Common neoplastic disease in ferrets
Adrena and pancreatic most common- endocrine disease
Cutaneous and subcut
lymphoid
Adrenal-associated endocrinopathy n ferrets
Common, middle aged to older ferrets
proliferative lesions adrenal cortex = excess amounts of oestrogenic hormones (hyperplasia, adenoma, or carcinoma)
Cutaneous, behavioural, and reproductive signs (not to be confused with Cushing’s disease)
Bilaterally symmetrical alopecia
Enlarged vulva in a spayed female
Islet cell tumour in ferrets
Common neoplasm
Hypoglycaemia due to inappropriate secretion of insulin
Clinical signs include: lethargy, stupor, ptyalism, and ataxia
Progressing to coma and death
Potentially malignant, metastasis is rare (cf dog and cat)
Skin and subcutaneous tumours in ferrets
Sebaceous epitheliomas
Mast cell tumours
Dermal leiomyomas, leiomyosarcomas (piloleiomyomas)
Vaccination-site fibrosarcomas
Lymphoid disease in ferrets
COMMON
Most are spontaneous, is there a retroviral infection?
1). older ferrets, primarily peripheral lymphadenopathy, visceral spread and subsequent organ failure late in the course of disease
2). young ferrets less than two years of age. Early visceral neoplasms, often with a large thymic mass
3). uncommon form, in which combinations of peripheral lymphadenopathy and visceral neoplasms and numerous bizarre lymphoblasts may be seen, known as the immunoblastic polymorphous variant.
Chordoma in ferrets
Most common neoplasm of the musculoskeletal system
Arise in or adjacent to vertebra from remnants of primitive notochord
Most commonly seen at the tip of the tail***
Also cervical spine
Chordomas are considered potentially malignant
Metastasis not seen in tail tumours
Cutaneous metastasis reported in one chordoma
from the cervical spine
Cardiac disease in ferrets
Cardiomyopathy – DCM, HCM and RCM
Heart may appear enlarged
Right ventricle may appear thin or flabby
Fluid in the abdominal cavity,
the pleural cavity, or both
Globose heart
Oral disease in ferrets
Dental disease
Salivary mucocoeles
Ulcerations
Neoplasia – squamous cell carcinoma! (fibrosarcoma, melanoma)
Oestrus-associated Aplastic Anaemia
Thrombocytopaenia:
Cutaneous haemorrhage
Melena
Swollen vulva
Xenobiotics
Xenobiotics are exogenous chemicals in the environment in air, water, food, and soil that may be absorbed into the body through inhalation, ingestion, and skin contact.
=poison =toxin
ADME
The basis of toxicology involves absorption, distribution, metabolism, and excretion (ADME).
Distribution is typically via the bloodstream.
The liver receives the portal circulation and is the organ most commonly involved in metabolism.
Excretion is largely dependent on water solubility-
Polar or aqueous-soluble agents tend to be excreted by the kidneys
Lipid-soluble chemicals- More likely to be excreted via the bile, Accumulate in fat
Metabolism of toxins
There are two phases of metabolism of toxins.
Phase 1 generally produces derivatives ready for phase 2 metabolism, but can also produce metabolites that can be directly excreted without phase 2
Phase 1 includes
Oxidation
Reduction
Hydrolysis
An important Phase I enzyme is cytochrome P450- MOST abundant in centrilobular (zone three) hepatocytes
Phase 2 principally involves conjugation.- Common conjugates include glucuronides, acetylation products, and combinations with glycine.
Important differences in metabolic mechanisms exist between species:
Cats lack forms of glucuronyl transferase, their ability to conjugate compounds is therefore compromised.
Toxicity
Xenobiotics can be directly toxic
Or Can be metabolised to non-toxic metabolites- Some species may be better at this: Dogs tolerate paracetamol, cats don’t- Glucuronidation
Xenobiotics can be minimally or non-toxic but then metabolised to a toxic metabolite: Ethylene-glycol, Organophosphates
Toxicity – gross appearance of liver
ZONAL PATTERN
Not specific however
Hypoxia- hepatocytes around central vein furthest from supply of oxygenated blood and then show damage more
Grossly it will not be clear whether centrilobular or periportal hepatocytes are affected
Assume centrilobular as more likely pattern
Important to differentiate from random- Viruses and some blood-borne bacteria
Toxicity – histopath of the liver
Centrilobular necrosis = toxic metabolites
Most common
Pyrrolizidine alkaloid-containing plants- Ragwort
Aflatoxins- Produced by fungi
Amanita mushrooms
Remember will have to rule out congestive heart failure- Chronic versus acute (chronic = chf)
Typically more degeneration and less necrosis
Peri-portal necrosis- Uncommon, Directly toxic straight from portal circulation, doesn’t need to be metabolised to have effect
Midzonal necrosis- Rare
Massive necrosis-
Relatively specific
Iron dextran
Vit E / Selenium deficiency
Xylitol
Differentials for Multiple acute deaths with additional neuro and/or respiratory signs in a herd
Carbon monoxide (see lecture later today)
Pig salt toxicity/water deprivation (see neuro lecture)
Urea/ammonia toxicosis- Slurry tank not cleaned out prior to using as water tank?
Toxicity – fixed samples
Brain
Heart
Lungs
Liver
Kidney
Toxicity – fresh samples
Urine
Stomach content
Kidney
Liver
Blood
Fat - chronic/fat soluble. Best place to test for PCBs (sea mammal predators have chronic depositions as they are lipid soluble)
Ethylene glycol pathophysiology
Ethylene glycol (EG) is a colourless, odourless alcohol with a sweet taste and is an active constituent of antifreeze
Pathophysiology-
Once ingested EG is rapidly absorbed by the gastrointestinal system and distributed by the bloodstream
Metabolism –
Gastric - mucosal alcohol dehydrogenase
liver - serial oxidation by alcohol dehydrogenase and aldehyde dehydrogenase= Rapid metabolism resulting in severe anion gap metabolic acidosis, this is what causes problem
Once converted to oxalic acid within 36 to 93 hours, calcium oxalate crystals precipitate in target tissues including kidneys, brain, heart and lungs.-
Hypocalcaemia
Renal azotaemia- Increased urea and creatinine, Low USG (however are often anuric)
Renal damage is due to:
acid metabolites of ethylene glycol, which can cause acute tubular necrosis, primarily of the proximal tubules
deposition of calcium oxalate crystals, primarily in proximal tubule epithelium
Neuro signs in farm animals- thyamine
Diagnosis of ethylene glycol poisoning
Diagnosis
History, time of year, clinical signs
Biochem, urinalysis and blood-gas results-
Renal azotaemia
Hypocalcaemia
High anion gap metabolic acidosis
Calcium oxalate crystals in urine
Urine will fluoresce under UV light
Urine for toxicology
Cats that have progressed to azotaemia tend to have bad prognosis
Post mortem-
Bilaterally mildly enlarged kidneys
Multifocal white streaking within cortex- Necrosis and calcification
Histopathology of kidney and brain
Tox testing – blood, urine, fresh kidney tissue
Anticoagulant rodenticide pathogenesis
Rodenticides can be split into following categories
First-generation anticoagulant rodenticides: warfarin, chlorphacinone, diphacinone
Second-generation anticoagulant rodenticides: brodifacoum, bromadiolone, difenacoum, difethiolone
Bromethalin - neuro toxin
Cholecalciferol – vitD3 analogue
Pathogenesis and pathophysiology-
Anticoagulant rodenticides inhibit vitamin K
Vitamin K is a cofactor of both intrinsic and extrinsic pathways of secondary haemostasis
Animals will bleed-
Disorders of secondary haemostasis tends to present with :epistaxis, GI, cavities, suffusive
compare disorders of platelets (primary haemostasis) – petechiation, ecchymoses
Diagnosis of Anticoagulant rodenticide poisoning
Diagnosis
Investigate bleeding
CBC-Regenerative anaemia
Blood smear-Regenerative anaemia, Normal number of platelets
Buccal mucosal bleeding time- Normal (1ry haemostasis)
Coagulation/clotting times- PT and aPTT will be raised
Post mortem
Haemorrhages into intestine and cavities
Histopathology not rewarding
Tox testing- Stomach content not always useful as can take several days to weeks from ingestion to manifest, Seen in heparinised blood and liver
Vitamin D poisoning pathogenesis
Vitamin D3 is also known as cholecalciferol
Found in
Rodenticides
Human medications- Tables, Creams (psoriasis)
Pathogenesis and pathophysiology:
Rapidly absorbed and metabolized by the liver and kidney.
The major toxic effects are due to the major metabolite, calcitriol (1,25-dihydroxycholecalciferol)
Calcitriol enhances-
Resorption of calcium from bone
Absorption of calcium from the gut
Proximal renal tubule reabsorption of calcium in the kidney
Results in hypercalcaemia-
Calcium deposits in soft tissue- Stomach, Kidney -> renal failure
Diagnosis of vitamin d poisoning
Diagnosis-
Biochemistry and urinalysis- Renal azotaemia and hypercalcemia (not pathognomonic)
Post mortem- Soft tissue mineralisation: Stomach wall, Serosal surfaces, Kidneys
Histopath- Stomach and kidneys (can see mineralisation)
Toxicity of non-steroidal anti-inflammatories
NSAIDs typically inhibit COX
COX enzymes required for multiple functions
Eg: aspirin is an analgesic, anti-inflammatory and anti-pyretic but also given to reduce clotting- 1ry haemostasis, Very very mild increase in BMBT
The primary toxic effects of NSAID are due inhibition of prostaglandins ->Vasoconstriction : in kidney-> renal failure (necrosis at renal pelvis), in stomach -> stomach ulcers
Hepatotoxins
Incomplete list of examples
Xylitol
Aflatoxins
Amanita mushroom (amanitin)
Blue-green algae (microcystin)
Heavy metals-Copper (see later)
Certain herbicides, fungicides, insecticides, and rodenticides.
Paracetamol- Cats»dogs
Idiosyncratic drug reactions
Diazepam
Carprofen
Methimazole
Pathophysiology
Liver failure- Raised ALT+ALP, Low albumin, Coagulopathies (2ry haemostasis), Jaundice (Increased Tbil), Hyperammonaemia (Hepatic encephalopathy, Ammonium biurate crystals in the urine), Multi-organ failure
Copper in small animals
Copper plays a critical role as a cofactor:
Cytochrome C oxidase - mitochondrial respiration
Lysyl oxidase - connective-tissue maturation (collagen cross-linking)
Superoxide dismutase - antioxidant defense
Tyrosinase - melanin synthesis
Ceruloplasmin - iron metabolism
dopamine β hydroxylase - neurotransmitter biosynthesis
In excess-
Catalyzes free radical formation
Accumulates intracellularly in the nucleus resulting in DNA damage and apoptosis
Mechanisms of toxicity-
Primary metabolic defect in hepatic copper metabolism- Bedlington terriers, autosomal recessive disorder of copper metabolism due to exon 2 deletion of COMMD1 gene causing progressive hepatic copper accumulation with age
Altered hepatic biliary excretion of copper
Excess dietary intake of copper
Gross lesions
Chronic changes – fibrosis, nodular regeneration, small liver
Diagnosis:
Histopath (centrilobular degeneration and fibrosis)- Special stains (rhodanine) for intracellular copper
Fresh sections of liver for copper levels
Copper in ruminants
Typically an acute crisis secondary to inappropriate bolussing or sheep being fed or breaking into cattle feed
Toxic to hepatocytes and erythrocytes-
Liver failure
Intravascular haemolysis
Renal failure
Haemoglobinuria
Gross pathology-
Liver variable
Kidneys bilaterally dark red and slightly enlarged with dark red urine
Paracetamol toxicity
Normal acetaminophen metabolism:
Phase I reaction via CYP450 -> toxic metabolite N-acetyl-p-benzoquinone-imine (NAPQI)
Phase II reaction (conjugation) via either:
Uridine diphosphate (UDP)-glucuronosyl transferase (glucuronidation) > excreted via bile and urine
Phenol sulfotransferase (sulfation) > excreted via bile and urine
Glutathione (GSH) (glutathione conjugation) > excreted via bile and urine
Pathogenesis and pathophysiology of overdose:
Phase II enzyme systems become saturated -> excess toxic NAPQI
-> excessive oxidative stress and cell damage in blood
oxidation of iron in haemoglobin and formation of methemoglobin (Fe2+ > Fe3+ = methaemoglobin) -> interference with oxygen transport -> cyanosis and brown mucous membranes
denatured haemoglobin precipitates on erythrocyte membranes ->Heinz bodies
oxidation and cross-linking of membrane proteins -> eccentrocyte formation
NB: Heinz bodies and eccentrocytes not pathognomic, just means oxidative damage – rule out onion toxicity
-> excessive oxidative stress and cell damage of hepatocytes
Centrilobular hepatic necrosis
Chocolate toxicity
Theobromine and caffeine
Clinical signs-
Polydipsia, vomiting, diarrhoea, abdominal distention, and restlessness.
May progress to hyperactivity, polyuria, ataxia, rigidity, tremors, and seizures.
Tachycardia, premature ventricular contractions, tachypnoea, cyanosis, hypertension, hyperthermia, bradycardia, hypotension, or coma may occur.
Death is generally due to cardiac arrhythmias, hyperthermia, or respiratory failure.
High fat content of chocolate products may trigger pancreatitis
No specific lesions at necropsy.
Grapes and raisins poisoning
Unclear pathogenesis
Renal failure
Metaldehyde poisoning
Slug bait
Neurological
Very sudden onset
Canabis poisoning
Ataxia, bradycardia, hypothermia, vocalization, hypersalivation, vomiting, diarrhoea, urinary incontinence
Avocado poisoning
Contains persin
Toxic to many species – birds and mammals
Cardiotoxic – see next lecture
Carbon monoxide poisoning
Carbon monoxide (CO) will most commonly be encountered by animals and people in poorly ventilated enclosed spaces heated by combustion sources- intensive animal production facilities
Also part of death in a fire, and produced by cars
Odourless and colourless
Pathogenesis- CO binds with high affinity to many ferrous heme-containing proteins.
Hb has a 250-fold greater affinity for CO than for oxygen.
CO competes with oxygen for binding to Hb and, by displacement of oxygen, reduces oxygen carrying capacity.
Clinical signs in people-
severe and persistent headache
dizziness, weakness, nausea, vomiting, chest pain, shortness of breath, irritability, and altered mental status
tachycardia, tachypnoea, hypotension
impaired memory and cognitive and sensory disturbances
Signs and necropsy in animals-
Mass death
Cherry red mucous membranes and organs
Plant toxins - liver
As with small animals the liver is commonly involved in poisoning cases.
In farm animals and equines this is often associated with toxic plants.
The most commonly associated is ragwort.
Pathogenesis and pathophysiology-
Pyrrolizidine alkaloids-
exists in the plant in two molecular forms
toxicity occurs when these are converted by liver microsomal enzymes (cytochrome P-450 monooxygenases)
Toxicity of PAs is due to centrilobular necrosis and antimitotic action
Centrilobular necrosis with megalocytosis in the liver
Typically a chronic disease- Fibrosis and biliary hyperplasia, regenerative nodules
Clin path-
Elevated liver enzymes
Herbivores – photosensitisation - > skin ulceration
Megalocytosis- Will see multiple and large nuclei as cells try to undergo mitosis but cannot
Toxins - heart
Many toxins are cardiotoxic
Plants-
Avocado
Foxglove (digitalis)
Yew
Rhododendron-Less acute, Only thing that makes goats vomit!
Drugs:
Ionophores- Coccidiostats/growth promoters
Typically peracute- Plant material found in GIT
Gross post mortem findings non-specific otherwise
Histopath-
Peracute/acute monophasic cardiomyofibre necrosis
Red maple (Acer)
Native to North America
Ornamental in UK
Wilted/dried leaves toxic, not green
Most commonly reported in horses
Unknown toxin causes oxidative damage to erythrocytes
Heinz body anaemia
Haemolysis
Methaemoglobin
Haemoglobinuria
Renal failure
Sycamore
Native to UK
Seeds (Autumn) and seedlings (Spring) toxic
Most commonly reported in horses
Atypical myopathy/seasonal pasture myopathy
Contain hypoglycin A- inhibit acyl-CoA dehydrogenases, causing degeneration of type I muscle fibres
Elevated CK
Myoglobinuria
Renal failure
Oak
Native to UK
Acorns (Autumn) and young leaves (Spring) toxic
Most common in ruminants but can occur in horses
Gallotannins are hydrolyzed to their active metabolites: tannic acid, gallic acid, and pyrogallol by fermentation in the rumen
Toxic to renal tubules-
Renal failure and haematuria
Bind to endothelium resulting in endothelial damage
-perirenal oedema, hydrothorax, ascite
Pathophysiology of red urine
A positive reaction for heme on a dipstick occurs in the following situations:
Haemorrhage(haematuria): This is the most common cause of a positive reaction.The reaction for heme on the dipstick is very sensitive and will detectheme associated with as few as 10 RBC/uL.
Intravascular haemolysis(haemoglobinuria)
Skeletal muscle injury(myoglobinuria)
How to tell the difference
Sediment exam
If once urine is spun down and the urine is clear it is most likely haematuria
Assess sediment for in tact RBCs
If present is most likely a urinary (or repro) source
UTI
Neoplasia
Pyo
If after spinning remains red is either haemoglobinuria or myoglobinuria- Look at biochem and CBC
Ammonium sulphate 80% will precipitate out haemoglobin not myoglobin
Bracken toxicity
Contains several toxins-
Ptaquiloside
Quercetin (carcinogenic)
Thiaminase
And a “bleeding factor” of unknown structure
Thiamine deficiency
Acute
Horses
Polioencephalomalacia
Ruminants
Acute-
Direct inhibition of bone marrow--> pancytopenia
->haemorrhage and neutropaenic septicaemia
Chronic- Co-infection with BPV, will result in GI or bladder tumours.
Fog fever
Pathogenesis-
Lush grass contains abundant L-tryptophan
Not toxic on its own but converted by ruminal bacteria to 3-methylindole - Pneumotoxic, Interstitial pneumonia
Clinical signs-
Respiratory distress
Foaming at the mouth
30% mortality
Gross pathology-
Diffuse widening of interlobular septa by fluid
consolidation
an exudate or other product of disease that replaces alveolar air, rendering the lung solid
sumerise urinary biochemistry
Elevated urae, kreatinie, usg and total protein is DEHYDRATION
Increased SDMA, urea and creatinine-
Azotaemia (term for the elevated levels)
Uraemia is the clinical manifestation (of azotemia) -Halitosis, tongue ulcers, etc
SDMA elevated earlier
When have these signs Also test USG- Low USG indicates tubular loss
Electrolytes-
NaCL decrease
K+ increases – blocked
K+ decreases – cats with CKD
Ca – Depends:, Hypo in ethylene glycol, end stage CKD, blocked, Hyper in AKI
Phosphate – increases
Urine protein- Increased with glomerular disease, UTI, canine HAC
With glomerular disease will also see low albumin
Kidneys produce EPO- Non-regen anaemia with CKD
Summerise liver biochemistry
Key differences in small versus large animals
Cat ALT and ALP have much shorter half life compared to dogs → smaller elevations are more clinically significant
Canine steroid ALP isoenzyme is elevated with both drugs (corticosteroids, phenobarbital), chronic stress, and hyperadrenocorticism
Bone ALP can increase with growth in young animals as well as patients with high osteoblastic activity (e.g. hyperparathyroidism)
Colostrum is high in GGT → increases in calves:
Can be used to check for passive transfer
Also elevated in foals but not due to colostrum
Others
Bile acids and bile acid stimulation test-
Liver function
Shunts ( other markers will be normal as liver is being bypassed)
Bilirubin
Icterus/jaundice
Cholesterol, albumin, urea and glucose-
All low in liver failure as made here
Coagulation factors (2ry haemostasis)-
Clotting times/aPTT and PT increased in liver failure
Think about this before biopsy!
List what blood tube you would pick for common samples taken in small animal practice
List what blood tube you would pick for common samples taken in small animal practice
Biochem-
Lithium heparin- Generally the orange top in small animals
Also fine for haematology in exotics
Haematology-
EDTA- Generally the pink or red top in small animals
Contaminating biochem sample will result in hyperkalaemia and hypocalcaemia
Glucose- Run immediately inhouse
Sodium fluoride/oxalate- Generally yellow top in small animals
Clotting times (2ry haemostasis)- Run in house
Sodium citrate- Generally the purple top in small animals
Endocrine-
Plain/gel tubes- Generally white or brown top in small animals
Serum
do lithium heprin before edta
Summarise haematology of erythrocytes
Haematocrit (HCT) is a calculated value- nRBCs x mean cell volume (MCV)
Packed cell volume is what you measure
Complete blood count versus haematology
Start with nRBC/HCT/PCV
If low = anaemia
Then have to decide if regenerative or not-
MCV and reticulocytes will increase
MCV is the average size of the erythrocytes
Reticulocytes are immature erythrocytes
Regenerative = disease happening in blood and bone marrow can respond
Non-regenerative = bone marrow disease, chronic illness especially CKD as kidneys make EPO
Iron-deficiency-
Microcytic hypochromic
Low MCV and low MCHC
Round and pale on smear
Polychromatophils are the same thing as erythrocytes but stained differently
poikilocytes
Acanthocytes- Lipid disorders
Liver disease
Shearing injury- DIC, Cancers: Haemangiosarcoma
Echinocytes- Prolonged storage (artefact)
Schistocytes-
Fragility (iron deficiency)
Shearing injury- Haemangiosarcoma
Spherocytes-
IMHA:Regenerative anaemia
Jaundice
In-saline agglutination
Coomb’s test
haematology – blue dit-dots
Reticulocytes/polychromatophils/basophilic stippling- regeneration
Heinz bodies- Oxidative damage
Onions
Paracetamol
Red maple
Not obvious with all stains- Methylene blue
Howell-Jolly bodies- Normal/regeneration
haematology – parasites
Cattle and dogs- Babesia
Cats- Mycoplasma haemofelis: Not the same one as respiratory
Camelids- Mycoplasma haemolamae
