Path Flashcards
1
Q
What should samples be fixed in?
A
at least 10x their volume of bufferred formalin.
2
Q
What stain is used for fat?
A
Oil Red O
3
Q
What stain is used for fibrous tissue?
A
massons trichome - stains ct green
4
Q
What stain is used for haemosiderin?
A
Perls Prussian blue
5
Q
What is pyknosis?
A
Small shrunken densely staining nuclei
6
Q
What is karyorrhexis?
A
The nuceus has fragmented into small pieces
7
Q
What is karyolysis?
A
Nucleus has lysed
8
Q
What is lipidosis?
A
Accumulation of intracytoplasmic lipid. the central role of the liver means that it is especially susceptible. the major mechanisms are excessive FFas into the liver or toxic damage affecting metabolism of fatty acids and triglycerides.
9
Q
What is pseudomelanosis?
A
green/black discolouration due to conversion of iron to iron sulphide by GI bacteria.
10
Q
What is biliary imbibition?
A
Pigment imbibed - onto liver and any organs in contact e.g GI tract.
11
Q
How does Rigor mortis occur?
A
Beings approx 2-4 hours after death. Burst of metabolic activity as substrates depleted on cessation of circulation progressive decrease in muscle Ph, Oxygen and ATP. Ca2+ efflux from sarcoplasmic reticulum of muscle cell > contraction of muscle fibres. Generally the head and neck musculature is affected first then the changes spread to the extremities. disappears as putrefaction begins (approx 1-2 days) Completely disappeared by 72 hours.
12
Q
what PM signs are seen when an animal is euthanased with barbiturates?
A
Spleen is congested & crystal deposition on the endocardium of the heart.
13
Q
What is splenic siderofibrosis?
A
yellow, dry encrustations on the capsule of the spleen thought to represent sites of previous local haemorrhage with usbsequent deposits of Fe, Ca and fibrosis.
14
Q
What does steroid use do to the liver?
A
long term steroid use can lead to steroid induced hepatopathy. pathogenesis : glucocorticoids induce the enzyme glycogen synthetase leading to increased storage of glycogen within hepatocytes. The hepatocytes in midzonal areas are often preferentially affected and can be up to 10x normal size.
15
Q
What is the role of the renin-angiotensin and aldosterone system?
A
Main role is in maintaining effective circulating volume. Renin is produced by specialised juxtaglomerular cells in the glomerular afferent arertiole. renin is released in response to decreased renal perfusion due to decreased blood pressure and decreased blood volume. Renin converts angiotensin to angiotensin I which then converts to angiotensin II. Angiotensin II increases aldosterone production by adrenal cortex > aldosterone enhances renal sodium absorption.
16
Q
What is the function of ADH?
A
ADH is made in the hypothalamus and released when hypothalamic osmoreceptors are stimulated. ADH controls permeability of distal tubules and collecting ducts. if ADH is present, urine volume is low. if ADH is absent, urine volume is high. Another stimulus for ADH secretion is decreased blood volume and pressure. Baroreceptors in the left atrium are stimulated by increased blood volume. Impulses pass in neurons to the hypothalamus where they inhibit ADH producing cells > urine volume is high which reduces blood volume and pressure. Decreased BP leads to decreased firing of baroreceptors and increased ADH secretion > urine volume is low > increased blood volume and pressure.
17
Q
What are Atrial natriuretic peptides?
A
A group of diverse peptide hormones produced by the heart in response to stretching of the heart, they reduce cardiac output and blood pressure through loss of NA and water from the kidneys as well as through vasodilation.
18
Q
What are the possible reasons for hypokalaemia?
A
Increased insulin activity, anorexia in herbivores, low K diet, GI disease especially horses, profuse sweating in horses, increased renal loss.
19
Q
What are the possible reasons for Hyperkalaemia?
A
Diabetes mellitus, high K fluid therapy, post renal obstruction, anuric renal failure, addisons disease.
20
Q
What are the possible reasons for Hypomagnesaemia?
A
Hypoporteinaemia, decreased absorption (grass tetany), anorexia, excess urinary excretion eg e.g ketonuria, blister beetle poisoning in horses, lactation tetany in shetland pony mares.
21
Q
What are the possible reasons for hypermagnesaemia?
A
Decreased renal excretion (renal failure, Decreased GFR), increased PTH (milk fever), increased intestinal absorption. Excess Iv administration.
22
Q
What are the possible reasons for hypocalcaemia?
A
Milk fever and eclapmsia in bitches, hypoproteinaemia, chronic renal failure, acute pancreatitis.
23
Q
What are the possible reasons for hypercalcaemia?
A
Malignant neoplasia
Renal failure in hrose
Thiazide diuretics, increased vit D activity.
24
Q
What is the protein content of transudate and exudate comparitively?
A
Tranusdate is 0.05-0.5% mainly albumin. Exudate is usually 2-4%, but can be higher. Transudate does not coagulate as no fibrinogen but exudate contains fibrinogen so will coagulate.
25
What is the cell content like in transudate compared to exudate?
Very low in transudate - mesothelial cells, some macrophages & lymphocytes. High cell count in exudates, any cel type potentially but more commonly macrophages, lymphocytes and neutrophils.
26
What is the difference in hyperaemia and congestion?
Hyperaemia occurs when arteriolar dilation increase blood flow to the tissue, which leads to tissue erythema e.g reddening at sites of inflammation. Congestion is due to reduced outflow of blood from a tissue ( a passive process e.g heart failure or vennous obstruction)
27
What does heart failure cause to happen to macrophages in the lung?
In chronic congestive heart failure - haemosidering laden macrophages within the lung alveoli due to capillary rupture in congested areas which leads to microscopic haemorrhages.
28
Classify the haemorrhages Petechiae, purpura, ecchymoses or rhetic?
Petechiae are very small 1-2mm and may be associated with locally increased vascular pressure, thrombocytopenia or decreased platelet function. Purpura is slightly larger >3mm and may be associated with the same conditions that cause petechiae or due to trauma, vasculitis or increased vascular fragility. Ecchymoses are larger (1-3cm) and rhetic affects large contiguous areas of tissue.
29
Give a summary of the process of haemostasis.
Injury > increased blood viscosity and RBC packing occur due to plasma loss > sludging effect > activated platelets change from small rounded discs to flat plates > release secretory granules which recruit more platelets > form a haemostatic plug > tissue factor III or thromboplastin is exposed at the point of vascular injury > this initiates coagulation cascade which results in formation of thrombin. Thrombin converts circulating fibrinogen into fibrin which is insoluble. Fibrin accumulates and forms a meshwork that recruits and activates more platelets to consolidate a primary haemostatic plug. Polymerization of this material forms a plug which stops further haemorrhage.
30
What is the fibrinolytic cascade?
prevents over production or persistence of fibrin. plasminogen in plasma is converted to plasmin by a factor XII dependent pathway or via plasminogen activators. Plasmin breaks down fibrin into fibrin degradation products.
31
What is the kinin system?
Predominantly associated with inflammation eg bradykinin acts as a vasodilator, increases vascular permeability which allows increased leucocyte migration, causes contraction of smooth muscle & pain.
32
What is the complement system
another cascade system with classic and alternative pathways. Inactive precursors in plasma are triggered by bacterial enzymes, antigen antibody complexes and thrombin. Complement system contributes to inflammation, phagocytosis of microbes and cell lysis.
33
What is thrombocytopenia and what are the possible causes?
Decreased platelet numbers in the blood. May be due to decreased production or increased destruction/utilisation of platelets. Decreased production due to bone marrow disease may be secondary to damage to megakaryoblasts in the bone marrow e.g myeloprofilerative disease, some viral infections, radiation injury, neoplasia and some drugs. Increased destruction of platelets may occur due to primary immune mediated disease, feline leukaemia virus, neoplasia or secondary to some drugs or diffuse endothelial damage such as disseminated intravascular coagulation, septicaemia or vasculitis.
34
What is von willebrands disease?
Due to a deficiency of the plasma glycoprotein von willebrands factor which is produced by endothelial cells. it acts as an adhesion molecule and is essential for primary haemostasis. it is common in dogs such as scottish terriers, dobermans and shelties. there are three types which vary in severity (type 3 is most severe form and is an absolute deficiency). Acquired coagulopathies include vitamin K antagonism, vitamin K deficiency and liver disease.
35
What is a thrombus?
A layered mass containing red blood cells, granular leucocytes and platelets held together by fibrin. An antemortem thrombus will be granular, dry, dull, and atatched to vessel wall or chordae tendinae in heart.
36
What are the three factors of virchows triad?
Damage to endothelium
Stasis or irregular /turbulent flow
Hypercoagulability of blood.
37
What is a common cause of arterial thrombosis in horses?
Secondary to strongylus vulgaris infection, seen in the root of the cranial mesenteric artery, renal artery and aorta
38
What is a common cause of arterial thrombosis in cats?
Iliac thrombosis secondary to cardiomyopathy and atrial thrombosis
39
What is an embolus?
A solid or gaseous mass carried by the bloodstream form its point of origin to a distant site within the circulation. Blockage of a major vessel such as the pulmonary arterial trunk tends to cause sudden death, blockage of a small end arteriolar vessels lead to ischaemia and infarction of the area supplied by the vessel.
40
What is an infarction?
A segmental or localised area of ischaemic necrosis due to occlusion of blood supply usually due to thromboembolic occlusion of an artery.
41
What is DIC?
DIC is characterised by the activation of coagulation within the vascular system resulting in deposition o fibrin in the small blood vessels and consumption of coagulation factors and platelets. The fibrin deposition within blood vessels leads to vascular obstruction and microinfarction. The fibrinolytic system is activated which removes some fibrin but also uses up clotting factors and forms fibrin degradation products which have anticoagulant properties. Causes include septicaemia, bacterial endotoxaemia, viral e.g feline infectious peritonitis
42
What are the three different types of shock?
Cardiogenic - failure of heart to pump blood adequately eg DCM or arrhythmias.
Hypovolaemic - reduced circulating volume resulting from blood loss or fluid loss.
Blood maldistribution - decreased peripheral vascular resistance and pooling of blood in peripheral tissues. It is usually caused by neural or cytokine induced vasodilation eg hypersensitivity, endotoxaemia. (Neurogenic, anaphylactic and septic shock)
43
what is neurogenic shock?
Usually induced by trauma, generally to the nervous system, electrocution, fear or emotional stress. Autonomic discharges > vasodilation > venous pooling.
44
What is anaphylactic shock?
Generalised type I hypersensitivity commonly caused by allergens, drugs or vaccines. the inciting substance interacts with IgE bound to mast cells > widespread mast cell degranulation > release of histamine > systemic vasodilation and increased vascular permeability > hypotension and hypoperfusion.
45
What is septic shock?
This is the most common form of shock due to maldistribution. it is mediated by vascular and inflammatory mediators released in response to bacteria or funal elements. the most common cause is endotoxin, a lipopolysaccharide in the cell wall of gram negative bacteria. LPS is a pattern associated molecular pattern. it binds CD14 and toll like receptor 4.
46
What are the clinical features of shock?
Hypotension, weak pulse, tachycardia, hyperventilation, urine production, hypothermia.
47
What is granulomatous inflammation?
Inflammation in which macrophages predominate, there is also giant cells and lymphocytes.
48
What is granuloamtous meningoencephalomyelitis?
An idiopathic disease which causes granulomatous disease in the central nervous system of young to middle aged small breed dogs. It causes a variety of neurological signs. Grossly there are few lesions. there may be some grey discolouration of affected areas in the brain and spinal cord.
49
What is salmon poisoning in dogs?
The etiologic agent of the disease is the rickettsia, Neorickettsia helminthoeca, which is vectored by the intestinal fluke, Nanophyetus salmincola. Dogs get the disease by eating salmonid fish infected with the cercaria of the fluke, which harbor the rickettsia. Clinical signs along with finding fluke eggs in the feces of the dog is usually enough to make the diagnosis. Paragonimus kellicotti is a lung fluke of the dog.
50
What is an adenoma ?
benign neoplasia of glandular epithelium
51
What is a papilloma?
benign neoplasia of surface epithelium
52
Which dogs are predisposed to developing mast cell tumours?
Boxers, boston terriers, bull terriers, bull mastiffs, cocker spaniels, labs, golden retrievers.
53
Which mutation is very common in mast cell tumours?
c-kit gene. which encodes for the KIT protein, which signals cells to proliferate.
54
Which granules do mast cells contain?
Histamine & heparine. Histamine causes vasodilation. It also binds to H2 receptor on parietal cells in the stomach and encourages them to produce gastric acid.
55
What is the neoplastic cell in Ovine pulmonary adenocarcinoma?
The clara cell found in the terminal bronchioles of the lung or the type II pneumocyte which lines the alveoli of the lung. Both of these cell types are surfactant producing cells and overproduction of surfactant is one of the more obvious clinical signs of this disease.
56
Histologically, how are squamous cell carcinoma made up?
Made up of cords or whorls of pleomorphic epithelial cells. Sometimes they have keratin pearls at the centre of the whorls.
57
What are the three main categories of cells?
Epithelial, mesenchymal and round cells.
58
List the general criteria of malignancy
Pleomorphism (variable size, shape and nucleus:cytoplasm ratio), macrocytosis, hypercellularity (increased cell exfoliation). Anisokaryosis, macrokaryosis, increased nucleus: cytoplasm ratio, multinucleation, increased mitotic figures, abnormal mitosis, atypical chromatin pattern, nuclear moulting (deformation of nuclei by other nuclei within the same celll or adjacent cells.
59
What is concentric hypertrophy?
There is an increase in the mass of the ventricle, the wall of which becomes thicker. there is either no change or a decrease in the end diastolic volume.
60
What is eccentric hypertrophy?
There is an increase in the mass of the ventricle, the wall becomes longer and chamber dilates resulting in an increase in end diastolic volume. In eccentric hypertrophy the ventricular wall may appear thin because it is dilated, but its mass is still greater than normal because the cells have increased in size by elongating.
61
Describe the pathophysiology of an atrial septal defect?
blood goes from LA > RA > RV = RA dilation and increased RV preload = eccentric RV hyertrophy.
increased pulmonary return = LA dilation.
62
Describe the pathophysiology of a ventricular septal defect?
LV > RV = inreased RV preload and afterload = RV hypertrophy
| Pulmonary overperfusion = increased pulmonary return = LA dilation and Increased LV preload = eccentric hypertrophy.
63
Which defects will be present in a tetralogy of fallot?
Ventricular septal defect, pulmonic stenosis, RV hypertrophy, dextro rotated aorta.
64
What is the pathophysiology of a PDA?
Patent ductus arteriosus (From aorta to Pulmonary artery). Increased RV aterload = concentric hyertrophy. Pulmonary overperfusion, increased pulmonary return, LA dilation and LV preload = eccentric hyertrophy.
65
What is a persistent aortic/branchial arch/vascular ring anomaly?
Of the six pairs of branchial arches present in the early embryo, normally only the left fourth arch persists as the aortic arch. persistent branchial arches are most commonly recognised in dogs and cats. the basic anomaly is constriction of the oesophagus as a result of anomalous vascular rings or associated structures. This results in megaoesophagus with regurgitation of undigested food i.e food never reaches stomach compared to vomiting. persistent right aortic arch is the most common manifestation.
66
Which of the following is the causative agent of Feline Infectious Anemia?
Mycoplasma haemofelis
67
What is ectopia cordis?
The heart is normal but is situated abnormally in the body. Cattle and pigs show the highest incidence of the condition. usually situated pre sternally in the lower cervical region or more rarely in the abdomen.
68
Which disease is hyaline degeneration of the myocardium typical of?
Most commonly a microscopic manifestation o the vitamin E/selenium deficiency white muscle disease, together with cardiomyocyte ncerosis, inflammation and dystrophic calcification. this disease presents as acute left heart failure or acute ataxia/collapse. muscles affected in white muscle disease include skeletal, intercostal, diaphragmatic and cardiac muscle.
69
What is visceral gout and why does this occur?
It occurs in reptiles and birds as in these species uric acid is the nitrogen metabolisms end product vs urea in mammals. Uric acid will precipitate in tissues as urate tophi (crystals) under certain circumstances (high protein diet, dehydration).
70
What is mulberry heart disease?
Seen in 3-4 month old thriving pigs. Considered to be the result from lack of selenium/vitamin E. This may be the result of low dietary vit/e selenium or genetic derangements of vit E /se metabolism. The cardiac presentation is similar to white muscle disease, with necrosis, although in this case there are also myocardial haemorrhages resulting from arteriolar fibrinoid necrosis.
71
What is malignant hyperthermia in pigs?
A rare genetic disease, due to a point mutation in the skeltal muscle ryanodine receptor. It is triggered by stress e.g handling, transportation and by halothane anaesthesia. This results in necrosis of cardiac and skeletal muscles which are then pale, soft and exudative interfering with the maturation of these into meat.
72
What is dilated cardiomyopathy?
Typically affects giant breed dogs such as boxers, dobermans, great danes, st bernards. Cases of DCM have been strongly associated with taurine deficiency in cats & correction of comercially available diets has reduced the incidence. Monensin toxicity has been associated with DCM in the horse and long term administration of drugs such as doxorubicin and adriamycin in dogs. Affected hearts are enlarged with uni or bilateral ventricular dilation, pale & flabby.
73
what is hypertrophic cardiomyopathy?
More common in cats, rare in dos. maine coons & ragdolls have mutations identified. The myocardial fibres are hypertrophied, and are accompanied by interstitial fibrosis and arteriosclerosis. There is marked cardiomegaly, Left ventricular concentric hypertrophy with concurrent thickening of the interventricular septum and normal or reduced internal left ventricular chamber size. Thrombus formation in the left atrium is common and when this thrombus breaks these animals develop aorti iliac thromboembolism with sudden onset posterior paresis.
74
What is restrictive cardiomyopathy?
Occurs less commonly in cats. these animals have marked myocardial fibrosis or endomyocardial fibrosis of the left ventricular endocardium. Marked left atrial dilation with a left ventricle of normal dimensions.
75
What is arrhythmogenic right ventricular cardiomyopathy?
This is primarily a familial disease of boxer dogs and is rare in cats. the right ventricular myocardium is replaced by fat and fibrous tissue. May present with arrhythmia, syncope, heart failure or sudden death.
76
What is the most common bacterial cause of endocarditis in cattle?
Arcanobacterium pyogenes
77
What is the most common cause of endocarditis in pigs?
Erysipelothrix rhusopathiae, strep suis
78
When a vegetative endocarditis lesion ruptures where do these cause lesions in cattle and in other species?
Right sided lesions in cattle causing pulmonary embolism and abscessation. Left sided lesions in pig dog and horse - myocardial and peripheral infarction and infection especially in the kidneys.
79
What are jet lesions?
Fibrous thickenings of the endocardium adjacent to an incompetent valve caused by back flow during systole. lesions may also occur in the aorta/pulmonary artery as a result of high pressure abnormal jets of blood passing through a narrowed stenotic semilunar valve and striking the vessel endothelium.
80
Where is the most common place for a haemangiosarcoma of the heart?
right atrium/auricle. Other primary sites include liver, spleen and skin. Metastases include lungs and brain.
81
What are heart base tumours?
They arise in the chemoreceptor cells in the aortic and pulmonary bodies (chemodectomas) they may metastasise although local enlargement tends to cause signs of dyspnoea, cyanosis and syncope first.
82
What is cor pulmonale?
Heart disease which is a consequence of chronic pulmonary disease. It usually infers isolated right heart enlargement following raised pulmonary resistance. causes might be primary chronic lung disease, pulmonary thromboembolism, mechanical obstruction or obliteration of pulmonary arteries or high altitude/mountain disease.
83
What are the possible sequelae of strangles?
Metastatic abscesses, bastard strangles (other organ involvement), guttoral pouch empyema or chondroid formation, purpura haemorrhagica (an acute vasculitis.
84
What is the cause of glanders?
Burkholderia mallei. The rhinitis of glanders is characterised by multiple small nodules in the nasal mucosa composed of cores of neutrophils surrounded by a rim of macrophages and granulation tissue. There is fever and head/neck lymphadenitis.
85
What is the most common cause of mycotic rhinitis in the dog?
Aspergillus fumigatus.
86
What does cryptococcus neoformans cause?
a granulomatous rhinitis in cats. Formation of nodules or destructive masses which often result in facial swelling. In severe cases, extension from nasal cavity to involve skin and oral mucosa can occur.
87
What is laryneal chondritis?
Cause is uncertain but appears to be a genetic predisposition in short necked breeds such as texels and southdowns, although any breed can be affected. More common in rams than ewes. Chronic suppuration within the arytenoid cartilages of the larynx resulting in swelling and occlusion of the lumen.
88
What is filaroides osleri?
A parasite which forms nodules around the tarcheal bifurcation - submucosal nodules upto 1cm in diameter. Associated with a mild chronic inflammatory reaction when the parasites are alive. When they die, an intense FB reaction occurs.
89
What are the common causes of kennel cough in dogs?
Bordetella bronchiseptica, PI2 and CAV2.
90
What is bronchiectasis?
Permanent saccular or cylindrical dilatation of the bronchi as a result of the accumulation of exudate within the lumen and partial rupture of bronchial walls. Cattle are particularly prone to development of bronchiectasis.
91
which lung lobes are normally affected by lungworm?
Lesions of patent dictyocaulus infections are preferentially associated with dorsocaudal and ventrocaudal regions. The gross lesions are characterised by wedge shaped areas of red/grey consolidation especially at the caudal edge of the diaphragmatic lobes.
92
What is aelurostrongylus and what species does this afefct?
Widespread cat lungworm. Adults live in the respiratory bronchioles and alveolar ducts. The gross lesions are evident as multifocal subpleural firm yellow nodules scattered throughout the parenchyma although they are more frequent at the periphery. Eggs and larvae in the alveolar space cause a foreign body type reaction.
93
What species does angiostrongylus affect?
A vasorum - parasitises pulmonary arteries and right ventricle of dogs and foxes where they cause a proliferative chronic arteritis and an interstitial eosinophilic pneumonia.
94
What is feline asthma/allergic bronchitis?
Inflammation usually dominated by eosinophils and some affected cats also have circulating eosinophilia. Causes recurrent cough/dyspnoea associated with bronchoconstriction.
95
Which type of hypersensitivity is COPD?
Type III
96
What is chylothorax?
Accumulation of chylomicron rich lymph, generally through traumatic or inflammatory rupture of the thoracic lymphatic duct. the thoracic duct runs along the right dorsal aspect of the thoracic aorta enters the precardial mediastinum to terminate at the junction of the left jugular vein and anterior vena cava.
97
What is myeloproliferative disease?
A non specific term describing disordered proliferation of one or more of the haemopoietic cell lines in the marrow.
98
What do chief cells produce?
pepsinogen
99
What do parietal cells produce?
HCL
100
What are the functions of tight junctions?
tight junctions between epithelial cells prevent entry of macromolecules and pathogens but allow ions and water to diffuse through.
101
What is the cause of wooden tongue?
Actinobacillus lignieresii
102
What is the cause of lumpy jaw?
Actinomyces Bovis
103
What is the most common oral neoplasm in the dog?
Melanoma - nearly always malignant in the oral cavity. Grow rapidly and are not always pigmented.
104
What are epulis?
a group of benign neoplasms of the periodontal origin affecting the gingivae. particularly seen in brachycephalic breeds such as the boxer. firm lesions on the gums, surrounding teeth, especially carnassial/canine region.
105
What is primary bloat?
Frothy bloat - due to formation of stable foam in the rumen, follows ingestion of excess high protein lucerne/clover or high concentrate, low roughage diet.
106
What is secondary bloat?
Mechanical/functional obstruction of the oesophagus.
107
Describe the pathogenesis of ruminal acidosis.
Excess carbohydrate > increase gram positive cocci> increase VFA > lactic acid production > drop in pH ruminitis > may allow thromboemboli to travel to the liver > hepatic abscessation.
108
What does clostridium septicum cause in sheep?
Acute abomasitis with red, thickened, necrotic haemorrhagic mucosa.
109
What is the difference between a volvulus and a torsion?
Volvulus - twist about hte long axis of the intestine e.g small intestine
Torsion - twist across the long axis of the intestine.
110
What are mesotheliomas?
Malignant neoplasms that arise from the serosa and form multiple small nodules. mainly seen in cattle and dogs.
111
What is the function of bile acids and where are they formed?
Bile acids are formed from cholesterol in the liver. the primary bile acids are converted to bile salts and are essential for the digestion and absorption of dietary fats. They act like a detergent, breaking up large fat globules into smaller droplets to form an emulsion with a higher surface area for lipases to act on. Bile salts also contribute to the formation of micelles. these are minute fat particles which are soluble in water and can readily be absorbed. 95% of the excreted bile salts are actively re absorbed in the terminal ileum and returned to the liver via the hepatic portal vein. this is called enterohepatic circulation.
112
How is bilirubin formed?
By the metabolism of haem breakdown products. When effete erythrocytes are removed from the blod by macrophages, the Fe ion remains int he macrophage bound to iron binding proteins. the remainder of the haem molecule is oxidised to biliverdin and then reduced to bilirubin.
113
What does ALT indicate?
ALT is liver specific and highly sensitive indicator of hepatocellular damage in dogs and cats.
114
what does increases in AST indicate?
Increase in AST tend to parallel those of ALT. AST is of less value since it is a ubiquitous enzyme with particularly high concentrations in muscle.
115
What is GLDH?
It is used in large animals as an indicator of hepatocellular damage as they have very little ALT in their hepatocytes.
116
What is Alkaline phosphatase?
AP is attached to the canicular membrans of hte hepatocytes and teh membranes of biliary epithelial cells. it is increased when there is intarhepatic or posthepatic cholestasis. There is also bone AP and intestinal AP.
117
what is GGT?
A membrane bound enzyme associated with the biliary tree. AP and GGT follow a similar pattern in liver disease.
118
What does increased bilirubin indicate?
Due to decreased uptake form the plasma by the liver, hepatic or posthepatic jaundice, although this is not specific and may be increased due to haemolytic disease.
119
What is the hepatic lobule?
A roughly hexagonal unit based on radiating sinusoids draining into a central vein with portal tracts at the corners.
120
What does a portal triad contain?
portal venule, hepatic arteriole, bile ductule.
121
What is nutmeg liver?
Lipid accumulates in the cytoplasm of injured hepatocytes due to their inability to metabolise/function normally. this may follow hydropic degeneration e.g right sided heart failure.
122
What is a portosystemic shunt?
An anomalous development of the portal vein either prior to the liver (extrahepatic) or within the liver (intrahepatic e.g persistent ductus venosus). Seen mainly in dogs and cats. features are liver and portal vein hypoplasia,.
123
What is portal hypertension?
When the accessory circulation of the liver is inadequate > portal hypertension develops > congestion and ascites. Portal hypertension may develop following severe hepatic disease, occlusion of the hepatic vein
124
What is triaditis in cats?
Chronic pancreatitis, enteritis and cholangiohepatitis.
125
What are the clinical signs of exocrine pancreatic insufficiency?
Fatty diarrhoea (Steatorrhoea), weight loss, voracious appetite
126
Which species get interstitial pancreatitis?
cats get acute and cats and horses get chronic interstitial pancreatitis. Extension of process tthat commences in the ducts, usually ascending infection of intestinal flora but can also be migrating parasites. Often occurs concurrently with cholangitis and enteritis in cats.
127
What are the four components of the nephrotic syndrome?
Proteinuria, hypoalbuminaemia, hypercholesterolaemia and oedema. Hypercholesterolaemia is caused by increased hepatic production and defective metbaolism of the VLDL fraction of lipoproteins.
128
What is urine protein:creatinine ratio?
Urine protein:creatinine ratio is used to quantify urinar protein loss in dogs and cats. it does not indicate the cause of proteinuria. The higher the value, the more likely that glomerulonephropathy is present. Values >5 are very suggestive of glomerular proteinuria.
129
What are the potential causes of acute tubular necrosis?
Ischaemic - eg severe hypotension.
| Nephrotoxic eg heavy metals, oxalates (ethylene glycol), aminoglycosides, tetracyclines, oak tannins, acorns (tannins)
130
What is pyelonephritis?
Pyelonephritis is inflammation of both the renal pelvis and the renal parenchyma and is associated with suppurative tubulointerstitial inflammation. usually results due to ascending infection from the lower urinary tract. Usual example is corynebacterium renale in cattle and eubacterium suis in pigs.
131
What types of tumours may occur in the kidney?
primary - renal adenocarcinoma - most common primary renal neoplasm in dogs cattle and sheep. Renal adenoma and nephroblastoma.
Occasionally primary haemangiosarcomas.
Metastatic renal tumours - ymphosarcoma common in cats and cattle, dogs e.g haemangiosarcoma, malignant melanoma, mammary adenocarcinoma.
132
What may cyclophosphamide cause?
Sterile haemorrhagic cystitis
133
Why may emphysematous cystitis occur?
Develops in some dogs and cats with diabetes mellitus - relates to fermentation of sugar by glucose fermenting bacteria.
134
Name the most common places for urinary obstruction with urolithiasis in dogs, bulls, rams and cats?
dogs - base of os penis
bulls - ischial arch, proximal end of sigmoid flexure
rams - vermiform appendate
cats - urethra
135
What is botyroid rhabdomyosarcoma?
Occurs in the bladder of young large breed dogs notably st bernards under 18 months. origin may be embryonic myoblasts. usually occurs at the trigone of the bladder as large fungating mass which is infiltrative and can metastasise.
136
Why may squamous metaplasia of the prostate occur?
following oestrogen administration or concurrently with testicular neoplasia notably sertoli cell tumour.
137
What type of neoplasia may occur on the prostate?
Prostatic adenocarcinoma is the most common form in old dogs. these tumours are usually highly aggresive and often metastasise to regional nodes and parenchymatous organs. additionally these tumours are capable of metastasising to lower lumbar vertebrae, pelvis and hindlimbs.
138
What is a true hermaphrodite?
An individual possessing gonadal tissue of both sexes. Rare due to failure of embryological differentitation of gonads during foetal life which leads to the presence of both ovarian and testicular tissue.
139
What is a pseudohermaphrodite?
Chromosomes and gonads are of one sex adn the ducts and external genitalia are modified towards or are of the opposite sex.
140
What is freemartin syndrome?
A freemartin is a masculinised female born co twin with a normal male. most female calves born cotwin to a male will be freemartins. placental anastomosis allows embryonic blood to be shared by the twins. Each twin acquires genetically distinct population sof blood cells from the other twin - chimaerism.
141
What is pyometra in the dog?
Accumulation of pus in the uterus as a sequel to hormonal disturbance with bacterial complication (e coli, staph aureus, streptococcus) in bitches it is seen in older animals, not bred, usually in post oestrus luteal phase a few weeks after being in heat. Elevated progesteroen with oestrogen priming leads to cystic endometrial hyerplasia. Mucoid secretion. Secondary bacterial infection - pyometra.
142
What type of placenta do the mare and pig have?
Diffuse
143
What type of placenta do dog and cat have?
Zonary placenta
144
What type of placenta do ruminants have?
Cotyledonary placenta. The cotyledon is the area of attachment of foetal placenta and the caruncle is the maternal endometrium of attachment site. Cows caruncles are convex and ewes are concave.
145
What are endometrial cups?
Present in mares. They develop from foetal tissue, visivle from day 40, pale and start to slough from day 100. They produce gonadotrophic hormones.
146
Why should bitches not undergo ovariohysterectomy during dioestrus?
Galactorrhoea may be seen - due to a prolactin surge
147
What are the two main bacteria isolated from sheep mastitis?
Staphylococcus aureus and manheimia haemolytica. These organisms result in acute necrotising or ganrenous mastitis so clinical presentation is often sudden unexpected death. Typically an enlarged, tense gland which may be discoloured blue with watery milk.
148
Which bacteria are usually involved in mastitis in dogs and cats?
Streptococcus and staphylococcus spp.
149
What is mammary fibroepithelial hyperplasia? (aka feline mammary hypertrophy)
Typically seen in young cats
150
Which glands does neoplasia affect in the dog?
Generally the fourth and fifth glands. These tumours are hormonally dependent so ovariohysterectomy prior to first oestrus decreases the risk of their development.
151
What type of tumours affect the mammary glands?
Approx 50% are malignant and metastazise to the lungs and regional lymph nodes. Malignant tumours include ductular carcinoma, carcinoma in situ, mammary sarcomas eg fibrosarcoma are also reported.
152
Describe the gross and histological appearance of a teratoma?
Irregular shape, solid & cysts, variable colour, on histology - chaotic, hair, cartilage bone and glandular tissue present. metastases are rare.
153
Describe the gross and histological appearance of a seminoma?
Spherical, large, soft and friable, white/grey in appearance, lobulated. on histology - homogenous sheet, round/polygonal cells, no fat in cells, mitotic figures. metastases rare.
154
Describe the gross and histological appearance of sertoli cell tumours?
Spherical, large, firm and cystic, white cream in colour, lobulated/nodular. on histology they have a tubular pattern, tall columbar cells, lipid in cytoplasm, mitotic figures. Metastases is rare.
155
Describe the gross and histological appearance of leydig cell tumours?
They are encapsulated, small to medium in size, soft & cysts, tan/orange in colour, may have haemorrhage. On histology they are solid sheets, polyhedral rounded cells, lipid vacuoles in cytoplasm. Metastases very rare.
156
What is feminisation syndrome?
Associated with sertoli cell tumours due to oestrogen production. They will be attractive to male dogs, decreased libido, symmetrical alopecia, mammary hyperplasia, preputial oedema, squamous metaplasia of prostate, contralateral testicular atrophy. may also have bone marrow suppression due to presence of high levels of circulating oestrogen.
157
What is posthitis?
Inflammation of the prepuce
158
what is balanitis?
Inflammation of the glans penis
159
What are the six major cell types in the CNS?
```
Neurons
Astrocytes
Micoglial cells
Oligodendrocytes
Ependymal cels
Choroid plexus epithelial cells.
```
160
What is wallerian degeneration?
Breakdown of an axon and its myelin sheath distal to the point of injury.
161
What are the possible causes of laminar cortical necrosis of the neurons?
Ischaemia (eg seizures in dogs), thiamine deficiency in ruminants, salt poisoning/water deprivation in swine and ruminants, lead poisoning in cattle, high sulphur intake.
162
What are the possible causes of neuronal vacuolation?
This is the hallmark of transmissible spongiform encephalopathies eg bse and scrapie.
163
What are the most susceptible CNS cells to injury?
Most susceptible to lease - Neurons > oligodendrocytes > astrocytes > microglia > blood vessels
164
What is malacia?
Grossly appreciable softening of the brain/spinal cord, usually resulting from necrosis. malacia occurs in infarcted tissue, but is not specific to infarcts.
165
What brain pathology would be seen in porcine salt poisoning?
Eosinophilic meningoencephalitis and perivascular eosinophilic cuffing in the cerebrum and meninges.
166
How do transmissible spongiform encephalopthies occur?
Prions are protein based infectious agents which lack substantial nucleic acid and are composed of PrPSC, the host encoded prion protein changes its structure into an abnormal isoform in the brains of affected animals. normal PRP becomes PRPSC, the disease associated form. this abnormal protein accumulates in nervous tissues as amyloid fibrils. Long incubation periods. The agent is highly resistant.
167
What microscopic lesions wil be seen with prion related diseases?
Spongiform change, astrogliosis, amyloid plaques.
168
what is the most common brain tmour in dog and cat?
meningioma - originates at the meninges and acts as a compressive space occupying lesion which seldom invades.
169
What types of brain tumour are common in brachycephalic breeds?
Astrocytma (solid, firm, grey white and sometimes mottled red with areas of necrosis/haemorrhage) and oligodendroglioma (soft grey to pink/red and often gelatinous).
170
What is the definition of a seizure? what is the pathogenesis of this?
A brain disorder manifested as a paroxysmal cerebral dysrhthmia. Pathogenesis - a small group of neurons periodically and spontaneously depolarise, this can occur due to structural biochemical or unknown causes. structural include neoplasms, inflammation or trauma and biochemical include hypocalcaemia, hypoglycaemia, hepatic encephalopathy. Idiopathic = no cause found. individuals believed to have a low seizure threshold which predisposes their neurons to depolarise of their own volition.
171
What is macaw wasting disease (proventricular dilatation syndrome)
Non suppurative inflammation of the central, peripheral and autonomic nervous systems, leads to gastrointestinal dysfunciton, wasting, anorexia and depression and neurological signs (ataxia, seizures). was considered to be idiopathic but now believed to be caused by avian borna virus.
172
What tubes should coagulation tests be done in?
Trisodium citrate
173
What tube should glucose testing be done in?
Fluoride oxalate
174
What are reticulocytes?
anucleate, immature RBCs with clumps of cytoplasmic RNA seen when stained with stains such as new methylene blue.
175
What are normoblasts?
Nucleated RBCs which are one stage less mature than reticulocytes.
176
What is cushings disease?
ACTH secreting pituitary tumour which results in adrenal cortical hyperplasia/hypertrophy and hypertorisolism (canine cushings syndrome).
177
How does hyperparathyroidism occur with renal failure?
retention of phosphorus and alterations in vitamin D metabolism lead to hypocalcaemia, with resultant hyperparathyroidism and skeletal demineralisation.
178
What is diabetes mellitus?
Diabetes mellitus is caused by relative or absolute lack of insulin from pancreatic B cells. It may be caused by destruction of islet cells secondary to pancreatitis, in cats it is often associated with amyloid deposition in the islets of langerhang, idiopathic pancreatic atrophy or hypoplasia.
179
What are the clinical signs of diabetes mellitus?
Reduced availability of insulin > hyperglycaemia, weight loss and weakness, reduced resistance to infection - leukocyte function is impaired, hepatic fatty change > cirrhosis, cataracts > bilateral lens opacity due to sorbitol pathway metabolism of glucose by the lens.
180
What is an insulinoma?
Neoplasia of the pancreatic B cells. carcinomas more common than adenomas. Usually functionally active > causes marked systemic effects. functional tumours cause marked hypoglycaemia.
181
What is a gastrinoma?
Neoplasia of the endocrine pancreas, uncommon compared to insulinoma. Gastrin cause hypersecretion of gastric acid > ulceration of gastrointestinal mucosa. vomiting, diarrhoea and weight loss. Invades pancreas then spreads to LN and liver.
182
What is primary hyperparathyroidism?
Chief cell neoplasia. adenoma more common than carcinoma. more common in the dog than other species. these tumours are often functional, causing bone resorption and hypercalcaemia due to increased levels of parathyroid hormone. may cause pathological fractures of the bones.
(Secondary= renal secondary hyperparathyroidism or nutritional secondary hyperparathyroidism).
183
Which cell type dominates in pemphigous foliaceous?
Neutrophil
184
what will be seen in pemphigous vulgaris?
intraepidermal vesicular dermatitis - minimal inflammation.
185
What is canine masticatory muscle myositis?
Autoantibodies selectively attack muscles of mastication (type IIM fibres). it manifests in the masseter and temporalis muscles, bilateral but not necesasrily symmetrical.
186
What is myasthenia gravis?
An acquired autoimmune disease where there are antibodies directed against acetylcholine receptors. associated with thymomas, megaoesophagus and hypothyroidism in dogs. Can occasionally be congenital - inherited deficiency in acetylcholine receptrs (rare).
187
What is the function of osteoblasts?
Form the bone matrix - osteoid
188
What are osteocytes?
Osteblasts that have become surrounded by mineralised bone matrix, occupy cavities called lacunae
189
What are osteoclasts?
Multinucleated cells derived from haematopoietic stem cells, responsible for bone resorption.
190
How is bone resorption controlled?
PTh - produced by chief cells in the parathyroid glands in response to decreased serum calcium
Calcitonin - produced by C cells in the thyroid glands in response to increased serum calcium.
Low calcium induces PTH secretion > osteoclasts increase in number > they attach to bone and resorb mineralised matrix > Ca2+.
191
What is the pathogenesis of renal hyperparathyroidism?
Chronic renal failure > retention of phosphate and inadequate production of vitamin K by kidneys > hyperphosphtaemia and hypocalcaemia > increased PTH output > increased bone resorption > fibrous osteodystrophy.
192
What is the pathogenesis of nutritional hyperparathyroidism?
Low calcium/high phosphate diets > decreased serum calcium > incraesed PTH > increased bone resorption.
193
What is osteoporosis?
Reduction in bone quantity not quality. bone resorption exceeds formation > pathological loss of bone. the bone which remains is normally mineralise. Causes include starvation, nutritional deficiency, senility, physical inactivity.
194
What is rickets?
Failure of mineralisation of physeal and epiphyseal cartilage during endochondral ossification and of newly formed osteoid. Mostly due to diets low in vitamin D or phosphorus. Growth plates are thickened as the zone of proliferation does not mineralise and mature, blood vessels and chondroclasts cannot invade so the cartilage is not removed. Metaphyses are flared because bone and cartilage cannot be removed, osteoclasts cannot bind to poorly mineralised bone - further accentuated by weight bearing.
195
How does hypervitaminosis A occur in cats and what are the effects?
Classically occurs in cats fed liver for prolonged periods, the vertebrae fuse with each other due to bone proliferation (ankylosing exostoses of the vertebral column) especially in the neck.
196
What is metaphyseal osteopathy?
seen in young fast growing dogs of large or giant breeds. the distal radius and ulna is most severely affected, bilaterally symmetrical. swelling in the metaphyses of long bones corresponding with neutrophilic infiltrate. most resolve spontaneously but can progress to periosteal bone proliferation. may wax and wane.
197
What is an osteocarcinoma? what are the predilection sites and prognosis?
A malignant neoplasm of mesenchymal origin in which the cells produce osteoid. generally very uncommon except in dogs and cats. giant breeds dogs are massively increased risk. strong site preference in dogs which is the proximal humerus, distal radius, proximal tibia and distal femur. (away from elbow towards the knee). Prognosis is poor due to early metastases.
198
What is hypertrophic pulmonary osteopathy?
Periosteal proliferation of bone on diaphyses and metaphyses of distal limbs, progressive and bilateral. most cases have an intrathoracic neoplasm or chronic inflammatory focus. but has also been associated with non thoracic lesions e.g botyroid rhabdomyosarcoma in the canine Urinary bladder and ovarian tumours in horses.
199
What is craniomandibular osteopathy?
Occurs in WHWT and Scottish terriers, arises at 4-7 months of age and is bilaterally symmetrial. Periosteal proliferation of bone leads to irregular thickening of the mandibular rami and some skull bones, including tympanic bullae.
