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66 Cards in this Set
- Front
- Back
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What kind of diseases cause visible cardiac lesions and which do not?
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Visible lesions may be seen from:
Coronary arterial thrombosis or embolism Nutritional deficiencies such as Vit E/Selenium deficiencies Bacterial or viral diseases Myocadial necrosis due to excessive catecholamine release following brain injuries Dysrrhythmias seldom produce observable lesions!! |
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What is the outcome of myocardial damage?
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Fibrosis. Repair is very limited! Most damage is irreversible.
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What is the hearts response to acute overload?
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Dilation!!!
If the dilation is moderate the heart will respond by increasing its force of contraction. If the dilation is more severe the heart may be stretched beyond its limits causing permanent chamber dilation. This decreases the force of contraction. |
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What might acute overload look like grossly?
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The heart will be larger and more rounded than normal and may be flabby.
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What is the hearts response to chronic overload?
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Hypertrophy!!
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In a horse or cow with right sided heart failure, where would you most likely see oedema?
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In the subcutaneous tissues of the ventral abdomen and brisket.
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In a dog with right sided heart failure, where would you find oedema?
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Abdominal cavity - ascites
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In a cat with right sided heart failure, where would you find oedema?
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Thoracic cavity - hydrothorax
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What would you find in the lungs of an animal at PM if it had left sided heart failure?
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Congestion and oedema
Lungs would be heavy and wet Cut surface would ooze fluid Froth within the airways Heart failure cells on histopath (haemosiderin within macrophages) |
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What are the causes of left sided heart failure?
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1. Myocardial degeneration or inflammation
2. Mitral valve stenosis or insufficiency 3. Congenital disorders 4. Cardiomyopathies |
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What are the causes of right sided heart failure?
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1. Left sided heart failure
2. Myocardial degeneration or inflammation 3. Cardiomyopathies 4. Increased pulmonary resistance such as in chronic interstitial pneumonia or altitude disease in cows 5. Hydropericardium or pericarditis 6. tumours near the heart base 7. Bicuspid valve disease |
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Describe the normal function of the ductus arteriosus.
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The ductus is a communication between the pulmonary artery and the aorta. In foetal life the ductus allows blood to bypass the lungs. This is because the foetus receives adequate O2 from the placental circulation.
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What happens to the ductus arteriosus at birth?
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The ductus responds to high levels of O2 entering the circulation via the lungs by vasoconstricting. This functional closure is soon followed by anatomical closure.
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What happens when the ductus arteriosus remains patent after birth?
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When the ductus does not close after birth, blood moves from the aorta into the pulmonary artery. This causes a blood overload in the pulmonary circulation, producing oedema. It also increases the amount of blood returning to the left atrium which means the LA and LV dilate and hypertrophy. The end result is left sided heart failure.
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What is the foramen ovale?
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The foramen ovale is located in the interatrial septum of the foetal heart. It functions to allow blood coming from the placenta to flow from the RA to the LA.
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What happens to the foramen ovale after birth?
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After birth, the high pressure within the LA functionally closes off the foramen ovale.
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What happens if the foramen ovale does not close after birth?
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There may be substantial flow of blood from the LA to the RA. This overloads the right side of the heart and makes it difficult for blood to enter from the vena cava. The backlog ultimately leads to right sides heart failure.
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What does the liver look like in an animal with right sided heart failure?
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Nutmeg liver. Areas of congestion within a pale fatty liver.
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What changes might you see in the heart of an animal with a ventricular septal defect?
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The hole is generally in the upper membranous part of the septum.
Both ventricular chambers hypertrophy. |
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What are the four defects found in tetralogy of fallot and in what breed of dog are you more likely to see it in?
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1. VSD
2. Pulmonic stenosis 3. Over riding aorta (straddles the left and right ventricle receiving blood from both chambers) 4. Right ventricular hypertrophy Keeshonds |
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What changes would you see in the heart of a dog with pulmonic stenosis?
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Right ventricular dilation and hypertrophy
Dilated pulmonary artery distal to the defect. |
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What animal commonly has valvular haematomas and what is their clinical significance?
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Common in young calves.
They have no clinical significance |
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What changes would you see in the heart of a dog with subaortic stenosis?
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Ranges from small subaortic fibrous plaques to thick fibrous bands encircling the aorta just proximal to the valve.
Will also see LV dilation and hypertrophy leading to left sided heart failure |
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What changes would you see in a cat with a tricuspid valve defect?
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The valve may be dysplastic or adherent to the endocardial lining.
The RA dilates and the RV hypertrophies leading to right sided heart failure |
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What changes would you see in a dog with mitral valve defects?
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LA dilation, LV hypertrophy and left sided heart failure
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What happens when there is a persistent right aortic arch?
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The ligamentous remnants of the ductus arteriosus encloses the trachea and oesophagus. The compression of the oesophagus prevents the passage of food.
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Which dogs are most at risk for developing endocardiosis?
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Male, small breed, older dogs
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What changes would you see in a dog with endocardiosis?
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Seen primarily in the mitral valve. Will see smooth, nodular thickenings of the valve, thickened chordae tendinae, dilation of the LA and jet lesions in the LA. The LV may also be somewhat dilated.
Leads to left sided heart failure! |
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What is the cause of endocardiosis?
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Unknown, however, a collagen defect has been suggested that leads to a mucinous deposition of ground substance within the affected valves.
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In what conditions might you find subendocardial mineralisation?
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1. Uraemia in dogs
2. Nutritional myopathies in lambs 3. Johne's disease in cattle 4. Vit D poisoning |
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Describe valvular endocarditis.
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Bacterial in origin. Causes large reddish-yellow vegetations on the affected vavles. This may spread down the chordae tendinae and lead to rupture.
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What predisposes to endocarditis?
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Recurrent bacteraemia
valvular damage certain bacteria such as Erysipelothrix rhusiopathiae selectively adhere to vavlular endothelium. |
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What is the outcome of vegetative endocarditis?
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It is generally fatal! Sometimes pieces of the thrombus can break off and enter the circulation as emboli, commonly lodging within the kidneys or spleen.
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What causes myocardial degeneration?
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toxaemias, pyrexic conditions, and anaemias.
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What does myocardial degeneration look like grossly and microscopically?
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Grossly the heart looks pale and flabby.
Microscopically the myocardial cells have small fat droplets within their sarcoplasm. |
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What is xanthosis and which breed of cattle are predisposed?
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Xanthosis is when a dark brown pigment develops within the heart muscle. It may accompany atrophy.
Ayrshires are predisposed. |
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What happens to the heart in Porcine Stress Syndrome?
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There is hypercontraction of the myofibres due to abnormal intracellular calcium. The papillary muscles of the ventricles are principally affected and it causes myocardial necrosis.
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Describe Mulberry heart disease in pigs.
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It causes sudden death in 3-4 month old pigs. Its due to a Vit E/Selenium deficiency. It causes acute congestive heart failure with cardiac haemorrhage and carcass congestion.
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Describe dilated cardiomyopathy.
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Most common in middle aged, large breed, male dogs.
Grossly, the heart is enlarged, rounded, pale, and the LV is most dilated, but the RV is also affected. Clinically, there may be A-fib, systolic murmurs, and congestive heart failure. |
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Describe hypertrophic cardiomyopathy.
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HCM is common in cats, especially persians. The walls of the ventricles, especially the LV, increase in thickness and reduce the lumen size. May be associated with hyperthyroidism.
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What are some causes of myocarditis?
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extension of inflammation from the pericardium or endocardium
Pyogenic bacteria toxoplasmosis FMDV in lambs and calves Parvo in young puppies parasites |
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What types of things might cause hydropericardium with a fluid content low in cells and low in protein?
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CHF
Tumours |
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What types of things might cause hydropericardium with a fluid content high in cells and high in protein?
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Acute toxaemias
Mulberry heart disease in pigs |
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What disease cause haemopericardium?
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Intrapericardial rupture of the aorta in horses or in pigs in association with copper deficiency
Rupture of a right atrial haemangiosarcoma in dogs Rupture of the left atrial wall in renal induced endocarditis Rupture of jet lesions from endocardiosis |
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Describe fibrinous pericarditis.
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Occurs as a result of haematogenous spread of infection.
The fibrin may organize into find strands of fibrous tissue and extend from the pericardium to the epicardium. |
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Describe purulent pericarditis.
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Seen commonly in the cow, eg: traumatic reticulitis-pericarditis.
When a metal object from the reticulum pierces through into the pericardium, it carries with it pyogenic bacteria that produce large amounts of pus within the pericardial sac. |
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Name three primary tumours of the heart
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rhabdomyomas
rhabdomyosarcomas Haemangiosarcomas |
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Name four secondary tumours of the heart.
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Haemangiosarcomas
lymphosarcomas carcinomas osteosarcomas |
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What is the significance of a primary haemangiosarcoma originating in the right atrium of the heart?
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It will readily metastisise to the lungs
It will often rupture causing sudden death as the animal bleeds out into its pericardial sac. |
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Where do heart base tumours originate from?
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They arise from the aortic body, a chemoreceptor organ situated between the aorta and pulmonary arteries.
The aortic body is responsible for monitoring O2 tension and CO2 levels within the blood. |
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What are the consequences of a heart base tumour and which breed of dog is predisposed?
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The tumours can become very large and interfere with blood flow through the atria, aorta and pulmonary arteries. They often lead to congestive heart failure.
Boxers are predisposed. |
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What disease in cattle causes lymphosarcoma of the right atrium?
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Bovine enzootic leukosis
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Describe arteriosclerosis.
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Its a hardening of the arteries with a loss of elasticity and narrowing of the lumen.
The abdominal aorta is principally affected. Common finding in older animals. It does not cause significant disease. |
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When might you see atherosclerosis in a dog?
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If the dog is hypothyroid with associated hypercholesterolaemia.
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What diseases may cause arterial mineralisation?
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renal induced hyperparathyroidism
vit D intoxication Johne's disease verminous arteritis in the horse old age |
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What is an aneurysm? What species are most commonly affected?
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A localised dilation of an artery due to a defect in its wall.
Its rare in domestic animals, but turkeys are most commonly affected. |
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What is a dissecting aneurysm?
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When there is damage to the intima leading to blood dissecting between the layers of the vessel.
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Describe aortic-iliac thrombosis in horses.
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Most commonly seen in racing TBs, especially young males.
The head of the thrombus lies at the aortic bifurcation and the tails extend down the iliac and femoral arteries. The thrombus interferes with blood flow to the hind limbs and causes intermittent lameness exacerbated by exercise. |
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Describe saddle thrombi in cats.
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The thrombus is located at the aortic bifurcation and causes acute hindlimb paresis. Its common in cats with cardiomyopathy. The thrombus itself may release vasoconstrictive amines that will further obstruct blood flow to the hind limbs.
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What is DIC and what may cause it?
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DIC is the pathological activation of intravascular coagulation. It is mainly seen in the smaller arterioles and capillaries of various tissue. It may cause all the clotting components in the blood to become used up leading to haemorrhage as a sequel.
Caused by: Viruses such as FIP Gram neg bacterial endotoxin Blood stasis |
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What is the cause of medial hypertrophy of the pulmonary arteries in cats?
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Unknown, however Aeleurostongylus abstusis (lungworm) has been suggested.
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Describe verminous arteritis in horses.
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Caused by Strongylus vulgaris.
The larvae penetrate the intestinal mucosa and migrate up to the root of the cranial mesenteric artery where the L4s remain for 3-4 months, moulting into immature adults, before passing back down to the intestines. In the Cr. mesenteric artery they induce extensive thickening of the artery with thrombus formation. |
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What is telangiectasis?
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Dilation of the sinusoids in the liver.
May be seen in small animals on prolonged steroid therapy. |
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What are angiomas and haemangiomas?
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Benign tumours of blood vessles.
Histologically you see proliferation of mature, thin walled vessels with flattened endothelial nuclei and extremely large lumens. |
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What are haemangiosarcomas?
What breed of dog are they common in? |
Malignant tumours of blood vessels.
Histologically you see proliferating vessels that are poorly formed and have plump endothelial nuclei. Common in German Shepherds |
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Where do haemangiosarcomas often originate from?
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Right atrium
Spleen Liver |
