respiratory 1 Flashcards
what is the stimulus for erythropoiesis and what occurs
hypoxia is the main stimulus
erythropoietin is the principle growth factor promoting viability, proliferation and differentiation
what are the sources of erythropoietin and what other growth factors work with it
○ Adults - kidney and to a lesser degree in the liver
○ Foetus - liver
○ e.g. stem cell factor, IL-3, thrombopoietin, androgens, glucocorticoids, growth hormone, thyroid hormone, insulin and IGF-1
what inhibits erythropoiesis
inflammation by reducing erythropoietin and its effect on the stem cells
- Mild anaemia
erythropoiesis what is the mother cell, what cells undergo mitotic divisions and what undergo maturation phase, how long does differentiation take
Rubriblast - mother cell
Rubriblast - Rubricyte
Maturation phase - from Rubricyte - Polychromatophil
mature erythrocyte nucleus is removed by macrophage
takes 3-5days under influence of erythropoietin
what occurs during maturation of red blood cells
1) haemoglobin increases
2) nucleus condenses
3) nucleus is then removed by macrophage
4) less blue more purple
how to tell if an animal is anaemic
↓ Haematocrit/Packed Cell Volume
↓ Erythrocyte/RBC count
↓ Haemoglobin level
- If any of these are low then it is anaemia
what are the 2 main causes of anaemia and what will occur in response
1) red cell loss -
1. haemorrhage
2. haemolysis
regenerative response
2) decreased red cell production - non regenerative response
what are some clinical signs of anaemia and more chronic signs
- Weakness and lethargy
- Pale mucous membranes - anaemic or circulatory disorder causing it
- Tachycardia
- Tachypnoea - faster respiratory rate
In severe cases can see - Cool extremities
- Weak peripheral pulses
- Heart Murmur
- Icterus - jaundice
- Shock
what are the classifications of regenerative and non-regenerative anaemia in terms of blood smear
Regenerative = marrow response evident - Reticulocytosis - Polychromasia - Hypochromic macrocytic anaemia Non-regenerative = no marrow response - Pre-regenerative or non-regenerative - No reticulocytosis, minimal polychromasia - Normocytic normochromic or hypochromic microcytic anaemia
what are the 5 ways in which we can assess for regeneration
1) blood smear
2) reticulocytosis = more acurate - need methylene blue staining
3) macrocytosis and hypochromasia - large erythrocytes with less haemoglobin however normocytic normochromic doesnt mean not regnerative
4) bone marrow evaluation
5) serial monitoring of PCV/CBC to assess improvement
in horses what is generally the only determinant of regenerative anaemia
macrocytosis
list some blood smear morphologic changes seem with regenerative anaemia
1) polychromasia
2) macrocytosis, anisocytosis, hypochromasia
3) increased Howell-Jolly bodies
4) increased nRBCs
5) basophilic stippling
what are the two ways in which reticulocyte counts are performed
1) manual reticulocyte count - use new methylene blue stain, count number reticulocytes per 1000 red cells
2) analyser reticulocyte count - use fluorescence stains - two forms in cats
1. aggregate reticulocytes
2. punctate reticulocytes
what are the two types of reticulocytes found in cats and what do they tell you are they found in health
Aggregate reticulocytes = polychromatophils
- Released in low numbers in normal dogs (1%) and cats (0.4%)
- If count generally just count this type
Punctate reticulocytes
- More mature form with only a few fine reticulin granules.
- Long maturation time in cats ( >2 weeks) so up to 10% punctate reticulocytes are seen in health
- Doesn’t tell you what bone marrow does today
what are the two ways in assessing the degree of regeneration and describe
1) absolute reticulocyte count
- retic% x RBC count - amount of reticulocytes per L of blood, normal within 0-120x10^9/L
- above the reference if regenerative
2) corrected reticulocyte %
- CRP = Retic % x (patient Hct / average species Hct)
- Want higher counts with more severe regenerative anaemia
birds, dog and cat what is normal correct reticulocyte percentage
- healthy birds 4-5% reticulocytes
○ CRP >1% in dog = regenerative
○ CRP >0.4% in cat = regenerative
what are the 3 anaemia erthrocyte indices
1) MCV - mean corpuscular volume
2) MCHC = mean corpuscular hemoglobin concentration
3) RDW - red cell distrubution width
what does MCV measure and what is the word to describe increase or decrease, what if normal
- Average volume of erythrocytes
- Measured value
- Increase = macrocytic - immature cells that haven’t condensed
- Decrease = microcytic
- Can have normal with regenerative
what does MCHC measure and what called if increase or decrease
mean corpuscular haemoglobin concentration
- Hb per average erythocyte
- Increased = Not possible
○ Artefacts: haemolysis, lipaemia, Heinz bodies
- Decreased = hypochromic
what does RDW measure and what does increase or normal mean
- Measures the variation in cell size
- Increased RDW indicates anisocytosis – could reflect macrocytosis and/or microcytosis
- normal - isn’t enough variation in size to effect - could still be regenerative
What occurs in terms of response to acute haemorrhage in the per-acute, acute stage 1 and acute stage 11
Per-acute
- No change Hct or protein
Acute Stage I (within hours)
- Decreased Hct and protein - combination - haemorrhage
○ Fluid shift extravascular to intravascular space
○ Activation of RAAS - PCV drops so can then detect
No evidence regeneration (pre-regenerative - per-acute and acute stage)
Acute Stage II (within 3-5 days)
- EPO produced - marrow stimulation
- Evidence of regeneration in blood
- Hct and protein start to rise if haemorrhage is controlled
what is the response to actue haemolysis in stage 1 and stage 11
Stage I (within hours)
- Decreased Hct with normal protein -
- No evidence regeneration (pre-regenerative)
- +/- haemolysed plasma and haemoglobinuria (as filtered by the kidney)
Stage II (within 3-5 days)
- EPO produced - marrow stimulation - Evidence of regeneration in blood
- +/- haemolysed plasma and haemoglobinuria
- Often see hyperbilirubinaemia/jaundice
- Hct starts to rise if haemolysis controlled
What are the 6 main findings with haemolysis
1) Haemoglobinaemia and haemoglobinuria (intravascular)
2) hyperbilirubinaemia and bilirubinuria
3) Regenerative anaemia (unless peracute)
4) Spherocytosis (if immune mediated haemolysis)
5) Schistocytes and keratocytes (if microvascular fragmentation)
6) Normal protein (no plasma loss)
what are 6 main causes of haemolytic anaemia
1) immune mediated haemolytic anaemia
2) oxidative injury - paracetamol in cats
3) infections - clostridium
4) zinc, copper toxicosis
5) genetic disease - PFK deficiency in dogs
6) neoplasia
what are the 3 types of IMHA and causes and what animals common
1) primary IMHA - idiopathic autoimmune - dogs common
2) secondary IMHA - common cats
- drugs, vaccination, infection - feline leukaemia viral infection, mycoplasma haemofelis, neoplasia, SLE
3) Alloimmune (Ab against foreign erythrocyte antigen)
- neonatal isoerythrolysis (colostrum produced antibodies) or blood transfusion
What are some key features for diagnosis of IMHA
- spherocytosis
- auto-agglutination in saline positive agglutination
- coombs test - looks for agglutination using antibodies
- exclusion of other primary diseases - infection, neoplasia, drug therapy
non-regenerative anaemia (NRA) what have to be careful with
need to differentiate from pre-regenerative anaemia - persistence > 5-7 days
- horses also don’t produce reticulocytosis
what are the two mechanisms of NRA
1) Reduced erythropoiesis = not making enough erythrocytes
2) Defective erythropoiesis = making abnormal erythrocytes
What are 4 causes of reduced erythropoiesis
1) Anaemia of inflammatory or chronic disease - common for mild non-regenerative anaemia
2) Decreased EPO production - most common is kidney disease
3) Immune mediated destruction of precursors (bone marrow cells)
4) Marrow diseases
Infectious diseases
what is the mechanism behind anaemia of inflammatory disease/chronic disease and laboratory findings
non-regenerative anaemia Mechanisms - Inhibition of EPO action - Iron sequestration (Hepcidin mediated) store within macrophage - body response to bacteria - Decreased erythrocyte survival Laboratory findings - Normocytic normochromic - Mild to moderate anaemia (Hct 20-30%) - Decreased serum iron - Evidence of inflammation or chronic disease
what are the two causes of decreased EPO production
1) Chronic renal disease –decreased EPO production, reduced rbc lifespan, GIT bleeding and uraemia suppression of erythropoiesis
2) Endocrine disease – hypoadrenocorticism, hypoandrogenism, hypopituitarism (mechanisms not understood)
immune mediated destruction of precursors what occurs, and why
- Pure red cell aplasia – selective loss of erythroid precursors from bone marrow
- Much less common than regenerative IMHA
- Appears to be immune mediated based on response to corticosteroids and/or lymphocytotoxic drugs
List 5 marrow disease that cause anaemia
1) Myelophthisis – infiltration of marrow by neoplastic cells eg lymphoma
2) Myelofibrosis – fibrosis of the marrow
3) Myeloproliferative disease eg leukaemia, myelodysplastic syndrome
4) Marrow toxicity/damage eg bracken fern, drugs (phenylbutazone), chemotherapy, radiation
5) Aplastic anaemia (concurrent leukopenia and thrombocytopenia) - less white, red blood cells and platelets
What are 3 infectious causes of non-regenerative anaemia
1) FeLV – killing of erythroid stem cells and progenitor cells along with dyserythropoiesis (macrocytic anaemia) - vaccination programmes
2) Anaplasma infection
- Ehrlichia canis infects monocytes, causes pancytopenia - exotic to Australia
3) Parvovirus – killing of rapidly dividing cells (haematopoietic cells, lymphoid cells, intestinal crypt cells), causing pancytopenia
List 7 causes of defective erythropoiesis
- Iron deficiency
- Lead poisoning - lead interferes with haemoglobin synthesis
- B12 or folate deficiency
- B6 deficiency - haeme synthesis
- Copper deficiency (defective iron transport)
- Marrow diseases
- Genetic and metabolic disorders
what is the most common cause of defective erythropoiesis, what is its hallmark with haemotology and mechanism
iron deficiency
hallmark: microcytic hypochromic
- in early stages when anaemia still slightly regenerative MCV and MCHC can be normal
- decreased iron leads to decreased haemoglobin synthesis allowing increased division before erythrocyte maturation
what are 3 causes of iron deficiency
1) Chronic external blood loss eg heavy internal or external parasitism, chronic GIT bleeding - lost in the faeces, chronic haematuria - cannot recycle
2) Defective iron transport/metabolism eg hepatic insufficiency - not large deficiency
3) Very rarely due to iron deficient diet - due to recycling of the iron within the body - neonatal animals more likely but still doesn’t really occur
lead poisoning what does it lead to, what due to, clinical signs and blood smear results
- defective erythropoiesis - non-regenerative anaemia
- ingestion of lead weight, lead paint
- clinical signs - GIT and nervous system signs
- Inappropriate (not with regenerative response) metarubricytosis and basophilic stippling - with no polychormatophils
what does deficiency in VIT B12, cobalt, folate, Vit B6 and copper lead to and mechanism for each
Defective erythropoiesis - non-regenerative anaemia
- Vit B12, Cobalt and Folate deficiency (defective nucleic acid synthesis)
- Vit B6 deficiency (defective haeme synthesis)
- Copper deficiency (Cu is involved in iron transport and absorption from intestine)
What are the 3 genetic disorders of erythropoiesis
1) microcytosis in asian dog breeds
2) macrocytosis of poodle
3) dyserythropoiesis
what are the two main metabolic disorders of erythropoiesis
- PFK deficiency Phosphofructokinase
- PK deficiency Pyruvate kinase Pyruvate kinase
Phosphofructokinase (PFK) deficiency mechanism and what breeds most likely
- Impaired ATP production and decreased 2,3 DPG resulting in alkalaemia induced haemolysis
- Episodic, often excitement induced (respiratory alkalosis)
- English springer spaniels and cocker spaniels
Pyruvate kinase (PK) deficiency mechanism, what result in, what breeds
- Impaired ATP production and increased 2,3DPG
- Causes decreased rbc lifespan - constantly produce more reticulocytes everyday
- Strongly regenerative macrocytic hypochromic anaemia with marked reticulocytosis progressing to myelofibrosis esp. dogs
- Abyssinian, Basenji
what are the 4 steps of diagnostic approach to anaemia
1) look at CBC (complete blood count) data
- assess degree of anaemia
- assess indicies - MCV, MCHC, RDW
- severe - red blood cell loss
2) blood smear evaluation
- evidence of regeneration
- morphology - ghost cells, spherocytosis, heinz bodies
3) consider the history, clinical signs, laboratory data
4) bone marrow evaluation for progressive persistent
Erythrocytosis/Polycythaemia what are the types, clinical signs
- can be relative due to dehydration when give fluids even out or absolute
- absolute erythrocytosis can be appropriate (high altitude - adaptive response) or inappropriate
- Clinical signs
○ Seizures
○ Behavioural changes
○ Red mucous membranes
○ Thromboembolic disease
List the 4 main causes of absolute erythrocytosis
1) primary - polycythaemia vera, rare disorder
2) secondary - increased erythropoietin - approraite or innappropriate
3) secondary - endocrinopathy associated
4) breed - greyhounds
what are 2 causes of relative erythrocytosis
1) dehydration - water deprivation, enteritis - haemorrhagic gastroenteritis
2) redistribution of erythrocytes - splenic contraction, adrenalin mediated, most common in cats (stressed) and horses (racing)
Characteristics of normal erthrocytes and differences in species
•Biconcave disc •Round with central pallor - Most prominent in dogs - Exception: Camelids have oval erythyrocytes •Anucleate - Exception: Birds, Amphibians, Reptiles - Size varies with species - Pigs & some goat breeds have variable shapes
relationship between polychromatophils and reticulocytes
All polychromatophils are reticulocytes but not all reticulocytes are polychromatophilic
- Polychromatophils can be seen normally or with wrights giemsa stian
reticulocytes - can be seen with new methylene blue stain as highlights RNA within the cell - always more reticulocytes then polychromatophils as not relying on eye sight to determine slight difference in colour
Aggregate vs punctate reticulocytes characteristics and when normal
Aggregate reticulocytes = polychromatophils
- Dark blue aggregates (clumps) - more than 3 clumps
- Released in low numbers in healthy dogs (1%) and cats (0.4%)
Punctate reticulocytes
- more mature form with only a few fine reticulin granules - faint blue dots
- Have a long maturation time in cats (weeks) so up to 10% punctate reticulocytes are seen in health
what are the 3 main morphologic changes with IMHA
1) agglutination
2) spherocytes
3) ghost cells
how to tell difference between mycoplasma and hell jolly body
If blue dot is in focus when cell is in focus - hell jolly body
If blue dot not in focus when cell is - mycoplasma
What are the 5 functions of the respiratory tract
1) gas exchange
- delivery of oxygen to circulatory system for distribution to tissues
2) vocalisation - specialised regions of respiratory tract
3) olfaction - specialised area lining of caudal part of nasal cavity
4) temperature control - cooling blood through evaporation of water in upper respiratory tract
5) acid-base regulation - regulation of blood pH
what is respiration and the 4 steps involved
passive movement of O2 from atmosphere to tissues and CO2 from tissues to atmosphere
- ventilation:
- movement of air into and out of lungs
- delivers O2 to and removes CO2 from lung - exchange of O2 and CO2 between alveolar air and blood
- transport of O2 and CO2 between lungs and tissues
- exchange of O2 and CO2 between blood and cells
list sections of upper and lower respiratory tract and what separates them
Upper respiratory tract: • nose - external nose - nasal vestibule - paired nasal cavities - paranasal sinuses • nasopharynx (with associated auditory tubes) • larynx • proximal trachea (to level of thoracic inlet) Lower respiratory tract: • trachea • bronchi • lungs separated by thoracic inlet
nose what made of, how move and different types
bony case with movable cartilaginous portion rostrally
• cartilages moved by muscles
• size and shape vary between species and breeds
- dolichocephalic (greyhound) - long nose
- mesaticephalic (beagle) - average size nose
brachycephalic (boxer) - short nose
external nose what are the structures in different species
specialized nasal integument (i.e. skin) in most species, surrounding paired nostrils
- modification of epithelium (hairless, thickened, often pigmented)
• variation between species:
- nasal plate (carnivores, small ruminants)
- nasolabial plate (cattle and ox) - nasal plate extends down to upper lip
- rostral plate (pig - contains rostral bone - helps the pig dig)
• philtrum - sagittal groove in rostral nasal integument
• nasal plate kept moist in some species (ox, pig - underlying glands; dog - overflow of secretions from nasal cavity)
nasal vestibule what is it, what is within and what is special about horse
- first part of the nose that the breath enters
narrow passage from nostril (= naris; plural – nares) to wider nasal cavity
• mucocutaneous junction within vestibule - site of opening of lateral nasal gland ducts (carnivores) and nasolacrimal duct in horse
• in horse divided into dorsal and ventral parts - dorsally - nasal diverticulum (= false nostril)
○ Important when giving nasogastric tube - put in ventral part - ventrally - true nostril leading to nasal cavity
nasal cavity function, how divided, what is the floor and how caudally limitied
- conducts air from nostrils to nasopharynx
- housed within bony casing, divided in the midline by nasal septum
- floor - hard palate separates nasal from oral cavity
- caudally limited by ethmoid bone
nasal cavity what lines it and function, how divided and how what communicate with through what
mucosal lining - helps warm air and also remove particulate matter
- divided into small passages by conchae (turbinate bones) covered in mucosa
- communication with nasopharynx through choana
nasal cartilages function what are the two types, how move and innovation and function of the cartilages themselves
• form framework of mobile part of nose
• include:
- septal cartilage (rostral part of nasal septum)
- several paired cartilages forming dorsal and lateral walls
• moved by levator nasolabialis and caninus (belong to muscles of facial expression - innervated by facial nerve = CNVII)
• muscle action to elevate lateral ‘wing’ of nostril (alar cartilage) increases diameter allowing greater air flow, e.g. sniffing (dog); strenuous breathing (especially in horse)
what are the 3 nasal conchae, characteristics and function
- dorsal - single elongated scroll
- ventral - rostral part of nasal cavity
- double scroll in most species
- horse - single scroll - completely enclosed space
- dog - complex, filling ventral part of nasal cavity - ethmoidal (= ethmoturbinates) (caudally) - numerous fine bony scrolls attached to ethmoid bone and lateral and dorsal walls
- support olfactory mucosa
• function to increase surface area for heat exchange, filtration and humidification of air by nasal mucosa, and for olfaction (ethmoidal concha)
- divide nasal cavity into dorsal, middle ventral and common nasal meatuses
lateral nasal gland what species present, where located, where duct opens and function
- only in carnivores
- large serous gland between mucosa and maxillary bone in lateral wall
- duct opens in lateral wall of nasal vestibule
- secretions important in wetting external nose
nasolacrimal duct what is it, location, openings in dog and horse
• duct which drains tears from eye to rostral part of nasal cavity
• proximal openings at medial canthus of eye (where eyelids meet medially)
• runs within lateral wall of nasal cavity
• distal opening in nasal vestibule
- at mucocutaneous junction in horse
- just ventral to alar fold in dog
paranasal sinuses what are they, how do they develop, how lines, what potential problem and the two types
• diverticula (outpocketings) of nasal cavity into skull bones
• develop after birth and increase in size with age
• lined with normal (secretory) nasal epithelium
• drainage of secretions through small openings into nasal cavity which can be blocked by mucus debris or mucosal congestion
1) frontal 2) maxillary sinuses
what is the possible functions of the paranasal sinuses
- lighten skull while allowing bony development for muscle attachment
- probably thermal and mechanical protection of soft tissues of head - would require more muscular activity to keep your head up
- resonance of voice
frontal and maxillary sinuses how large, where communicate to, special characteristics
1) Frontal sinuses
• Small in the dog and horses, larger in cattle and pigs
• drain into ethmoid region (except in horse)
• extend into cornual process (base of horn) in ruminants - when dehorn adult will be opening to the outside
2) Maxillary sinuses
• communicate with nasal cavity through narrow nasomaxillary opening except in dog and cat (wide opening ⇒maxillary recess)
• house roots of upper cheek teeth - as check teeth continue to erupt the sinuous grow
• in some species further diverticula into adjacent bones (⇒ e.g. palatine sinus)
paranasal sinuses in the horse characteristics where enter into
maxillary sinus:
- rostral and caudal divisions
- partly filled by unerupted cheek teeth
• frontal sinus:
- extends into dorsal concha (which is closed off from nasal cavity)
- drains into caudal maxillary sinus - not into the nasal cavity
• drainage of all sinuses into nasal cavity through narrow common nasomaxillary opening - blockage easier
clinical importance of paranasal sinus in the horse
- may need to gain access for surgical drainage or tooth removal (upper check teeth)
what are the important landmarks in accessing the maxillary sinus
1) nasolacrimal duct
2) line between infraorbital foramen (large hole on surface of skull) and medial canthus of eye
3) facial crest - big ridge of bone
4) line between infraorbital foramen and rostral border of facial crest
5) vertical line through medial canthus of eye
what are the 2 areas of the nose in birds
1) cere - soft, keratinized tissue at base of upper beak in some birds (e.g. psittacines, pigeons)
- can be used to sex budgerigars (blue in male, brown in female)
2) palate - no soft palate, no nasopharynx, elongated medial choana
3) infraorbital sinus - diverticulum enclosed by caudal concha
4) nasal gland - located in lateral wall of nasal cavity
- secretes sodium in marine birds (salt gland)
what is the narrowest part of the airway and how can obstruction of this affect airflow
the larynx - airflow proportional to r^4
upper airway obstruction when hear noise
- if total obstruction don’t hear noise
- early stages of obstruction only hear noise during excercise
- if can hear noise at rest then severe
why hear noise during excercise first before rest with upper airway obstruction
- Bigger inspiratory effort – bigger pressure gradient, bigger airflow
- Maximally open larynx (abduct arytenoid cartilages)
- Soft tissues of URT have to resist bigger negative pressure – sometimes they fail this causes a functional problem, that may not be apparent at rest.
mouth breathing what animals are obligate nasal breathers and what can mouth breath but only when seriously sick
Obligate nasal breathers - upper respiratory tract inflammation can be problem
- Horses - large nasal passages just generally not totally obstructed
- Rabbits
- Rodents
• Cats, sheep, cattle can mouth breath - (but only do so when seriously ill)
if nasal discharge is uni lateral what does that indicate
Indicates an URT problem usually:
- Nasal passage - Paranasal sinuses - (Guttural pouches)
what causes sneezing and coughing
Sneezing –nasal passage irritation - upper respiratory
Coughing – trachea/ bronchi irritation - generally lower respiratory
what is the most common cause of inspiratory dyspnoea in horses and characteristics
strangles
- infection with bacteria
- uni or bilateral nasal discharge or none at all
- URT retropharyngeal lymph node abscessation - need to drain
- highly contagious between horses
what is the main cause of nasal discharge in cows and causes
Bovine Nasal Granuloma (allergic rhinitis)
- Nasal Discharge (lick there noise so needs to be perfuse to see it) and itchy noises
- Common cause of feign bodies up the noise of cows - trying to scratch the inside of their noise
what is an important upper respiratory tract disroder in calves what involved and signs
Calf diphtheria
- Laryngeal (& oral necrobacillosis)
- 2nd invasion of ulceration by Fusobacterium necrophorum
- Ulcers form from paroxysmal coughing, constant vocalisation (weaned) possibly mild URTIs or inhaled irritants
what is involved in brachycephalic syndrome in dogs and what breeds
1) Stenotic nares
2) Elongated soft palate
3) Everted laryngeal saccules - get caught up in airway
- boxes, pugs, bulldogs
what would you expect with stronger regenerative response compared with mild
○ stronger regenerative response - would get macrocytic hypochromatic
○ Mild regenerative response - normocytic - average cell size not high yet as more normal than immature (large cells)
with white and red blood cells with suffixes are used for increase and decrease amounts
-phila (increase) -nea (decrease)
What are the two treatments for severe anaemia and why
1) IV fluids + potassium
○ Need to correct hypokalaemia as decreased due to not eating - get from diet
- Makes them more weak, contribute to weakness and lethargy, skeletal muscle problems
2) Blood transfusion - Concentrated RBCs
○ Need to increase the oxygen capacity of the blood by increasing the amount of red blood - Adding whole blood would increase blood volume which can increase preload and afterload on the heart without increasing the proportion of RBCs
why wouldn’t you add whole blood to anaemic patients
- Adding whole blood would increase blood volume which can increase preload and afterload on the heart without increasing the proportion of RBCs
what is a possible risk from IMHA and why
Risk of thromboembolism
due to inflammatory processes causing intravascular endothelial damage
