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80 Cards in this Set

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What is meant by the term hydropericardium?
accumulation of non-inflammatory fluid in the pericardial sac
What are the possible mechanisms by which hydropericardium develops?
right-sided congestive heart failure

Hypoalbuminarmia due to protein-losing enterophathy, protein-losing nephropathy, chronic liver disease

local venous or lymphatic obstruction dt tumours at the heart base or in the cranial liver disease

increased vascular permeability dt vitaminE/selenium deficiency in pigs, uraemia b/c of renal failure, acute clostridial intoxication
What are the typical gross features of hydropericardium?
clear colourless or pale yellow fluid

may form a gel on exposure to air if rich in protein (=fibrinogen)

serosal surfaces remain smooth and glistening unless the effusion is chronic

in chronic case, may see mild fibrous thickening and opacity of the serosa, especially about the base of the ventricles
What is meant by the term cardiac tamponade?
Compression of the heart due to collection of fluid or blood in the pericardial sac (= hygropericardium or haemopericarium), leading to impaired atrial and ventricular filling.

*usually due to rapid effusion of fluid rather than slow effusion → rate is imp!!
What is meant by the term haemopericardium?
presence of free blood (usually clotted) in the pericardial sac

*less common than hydropericardium
*commonly fatal
What are the typical gross features of haemopericardium?
the dark blood in the pericardial sac

presence of bree blood (usually clotted) in the pericardial sac
What are some causes of haemopericardium in domestic animals?
penetrating trauma with puncture of the heart or a coronary vv

rarely, spontaneous rupture of a coronary artery or cardiac neoplasm

Dog: bleeding haemangiosarcoma
coagulation factor deficiency

Horse: rupture of the intrapericardial aorta or p.a.

Cattle: foreign body penetration from the reticulum
What are the potential consequences of haemopericardium?
commonly fatal dt cardiac tamponade
What are the two main types of pericarditis seen in domestic animals?
fibrionous pericarditis

supprative pericarditis
How does fibrinous pericarditis usually arise in domestic animals?
usually results from haematogenous infection and is often part of systemic infection

occasionally dt spread of infection or inflammation from adfacent tissues, especially lungs or pleura
In which species is suppurative pericarditis most commonly seen and why?
cattle with traumatic reticulopericarditis ('hardware disease')

in cattle, ingested foreign bodies are accomodated in the reticulurm, which can penetrate the reticulum, throgh the diaphragm to the pericardiac sac → traumatic pericaditis & infection with bac
What are common causes of haemorrhage over the epicardium and/or
endocardium in domestic animals?
epicardial haemorrhage: common in many acute infections (eg bacteraemia, septicaemia, toxaemia, viraemia), also seen in haemorrhagic diatheses (DIC, coagulation factor deficiency), in pig, due to mulberry heart disease

Endocardial haemorrhage: as per epicarcdial haemorrhage, but less common
What is meant by the term jet lesion?
localized areas of subendocardial fibrosis, usually in the atria, thought to be dt abnormal jets of blood caused by valvular lesions
What is the usual cause of diffuse subendocardial fibrosis?
-prolonged subendocardial oedema
-dilated cariomyophathy in dogs
In what circumstances can mineral be deposited in the endocardium?
-chronic dilation of heart chambers, especially left ventricl
-in chronic debilitating disease in cattle such as Johne's disease)
-vitamin E/selenium deficiency in lambs and calves
-poisoning with vit D or vitD analogues
In which species is suppurative pericarditis most commonly seen and why?
cattle with traumatic reticulopericarditis ('hardware disease')

in cattle, ingested foreign bodies are accomodated in the reticulurm, which can penetrate the reticulum, throgh the diaphragm to the pericardiac sac → traumatic pericaditis & infection with bac
What are common causes of haemorrhage over the epicardium and/or
endocardium in domestic animals?
epicardial haemorrhage: common in many acute infections (eg bacteraemia, septicaemia, toxaemia, viraemia), also seen in haemorrhagic diatheses (DIC, coagulation factor deficiency), in pig, due to mulberry heart disease

Endocardial haemorrhage: as per epicarcdial haemorrhage, but less common
What is meant by the term jet lesion?
localized areas of subendocardial fibrosis, usually in the atria, thought to be dt abnormal jets of blood caused by valvular lesions
What is the usual cause of diffuse subendocardial fibrosis?
-prolonged subendocardial oedema
-dilated cariomyophathy in dogs
In what circumstances can mineral be deposited in the endocardium?
-chronic dilation of heart chambers, especially left ventricl
-in chronic debilitating disease in cattle such as Johne's disease)
-vitamin E/selenium deficiency in lambs and calves
-poisoning with vit D or vitD analogues
What is endocardiosis and how would you recognise it grossly?
= myxomatous valvular degeneration

-thickening of valve by loose fibroblastic tissue and deposits of glycosaminoglycans
-valve leaflets bocome short and thick
-small discrete nodules at free margins of valves or more uniform valve thickening
-thickened chrdae tendineae
What are the potential consequences of mitral or tricuspid endocardiosis in a dog?
valvular insufficiency → regurgitation of blood during systole → atrial dilation and ventricular dilation

diffuse subendocardial fibrosis in chronically dilated chambers

jet lesions in atrium due to blood regurgitation

LA rupture → haemopericardium and cardiac tamponade

Chordae tendineae rupture → eversion of valve into atrium → acute ventricular failure

congestive haert failure
What is the usual cause of endocarditis in domestic animals?
usually bacterial in origin but occasionally dt parasites or fungal infection
Why is valvular endocarditis much more common than mural endocarditis?
valves are more likely to get repetitive trauma which damage endothelium, promoting throubogenesis with subsequent deposition of bacteria than the endocardium
What are the potential consequences of valvular endocarditis?
pyrexia, lameness dt immune complex-induced arthritis and a cardiac murmur

valvular stenosis or indufficiency → congestive heart failure

embolism - bland or septic
- RH emboli → pulmonary thromboembolism or abscessation
- LH emboli → septice or sterile renal or splenic infarcts
What are the possible causes of mural endocarditis?
extension of vaulvular endocarditis - esp with A. pyogenes in cattle

extension from focal myocarditis, especially myocardial abscesses
What are the five major mechanisms responsible for heart failure?
1.sustained pressure overload
2.sustained volume overload
3.depressed or altered contractility of myofibres or loss of myofibres
4.abnormal heart rate or rhythm
5.reduced ventricular compliance
What are the systemic neurohumoral compensatory mechanisms that are activated in response to a decrease in cardiac output?
-activation of the SNS
-activation of the renin-angiotensin-aldosterone system
Why are these systemic neurohumoral compensatory mechanisms ultimately deleterious to an animal with heart disease?
These mechanisms lead to retention of Na & water and expansion of the blood volume. ultimately ↑ing vol loads on the heart during diastole

sustained activation of SNS → ↑pressure loads during syslole, also bsroreceptor responsiveness declines → decreased vagal inhibition and sustained sympathetic and hormonal activation
What is meant by the terms volume overload (preload) and pressure overload (afterload) with respect to cardiac workload?
volume overload = ↑diastolic work load = an ↑ in the volume of blood entering a heart chamber during diastole

pressure overload = ↑ed systolic work load
= increase in resisitance to chamber outflow during systole
What is meant by the terms valvular stenosis and valvular insufficiency?
Both are heart valve abnormalities
valvular stenosis = narrowing, failure to open

valvular insufficiency = failure to close
What disorders lead to volume overloads on the ventricles?
-valvular insufficiency
What disorders lead to pressure overloads on the ventricules?
-all semilunar valve stenoses, outflow stenoses and hypertension
What disorders lead to decreased volume loads on the ventricles?
all atrioventricular valve stenoses and pericardial disease
What is meant by the term cardiac dilation?
pathological enlargement of one or more heart chambers, with thining of the chamber wall and an increase in chamber volume
What causes cardiac dilation?
volume overload, especially when it's acute
What are the advantages of cardiac dilation?
●frank-starling phenomenon (↑ in the endo-diastolic volume of the chamber → stretching or rearrangement of myofibres → ↑ contractile force & stroke vol)
What are the disadvantages of cardiac dilation?
stretch of chamber beyound its limit causes decreased tension development and decreased contractility → flabby inefficient heart with loss of contractile force

less energy-efficient than a normal heart

dilation → 2 times larger chamber → 2 times more tension in the chamber

risk of failing b/c it must expend a dsporportionate amount of energy to eject the blood volume
What is meant by the term concentric cardiac hypertrophy? To what is ti a response?
an increase in mocardial mass without an increase in endo-diastolic volume

it is a chronic response to sustained pressure overloads (eg. pulmonic stenosis, subaortic stenosis, systemi hypertension)
What are the advantages and disadvantages of concentric cardiac hypertrophy?
+ve: the radius of the chamber is the same or decreased → the tension needed to raise the intra-ventricular pressure to eject blood may be normal or even reduced in hypertrophy

-ve: if cause is remained, heart will eventually fail
hypertrophied myofibres have reduced contractility
no increase in myofibre mitochondria, in capillary bed
What is meant by the term eccentri cardiac hypertrophy? To what is it a response?
an increase in myocardial mass accompanied by an increase in end-diastolic volume (chamber volume)

it is a chronic response to sustained volume overloads
What is meant by the term forward failure of the heart? What clinical signs might be seen in animals with forward failure?
forward failure = inadequate cardiac output

it can occure in arrythmias, hysrhythmias, right-to-left shunts etc.

it can manifest as
-exertional weakness and tiring
-syncope
-cyanosis
-prerenal azotaemia dt ↓d glomerular filtration rate
-mucous memb pallor
-delayed capillary refill time
What causes congenital cardiac anomalies in domestic animals?
-genetic
-foetal hypoxia
-exposure of pregnat dams to such as thalidomide, ethanol,X-ray etc or to deficiencies of vitamin A, zinc, pantothenic acid or riboflavin or to excesses of viatmin A or copper
What are the most common congenital cardiac anomalies in dogs?
PDA
pulmonic stenosis
subaortic stenosis
PRAA
What are the most common congenital cardiac anomalies in cats?
AV valve dysplasias, ASD, VSD and endocardial fibroelastosis
What are the most common congenital cardiac anomalies in pigs?
subaortic stenosis, endocardial cushion defects
What are the most common congenital cardiac anomalies in cattle?
ASD
VSD
Transposition of major vessels
valvular haemocysts
What is patent ductus arteriosus (PDA)?
failure of closure of foetal arteriosus which usually close in the first few hours to days after birth
What are the consequences of a patent ductus arteriosus post-natally?
Uncomplicated PDA → overload on pulmonary circulation, LA, & LV → eccentric hypertrophy of LV → as pulmonary hypertension fevelops, RV sustains a pressure overload → concentric hypertrophy

complicated PDA → venous blood bypasses the lungs leading to cyanosis of the hindquarters
Is a patent foramen ovale significant? Why?
not significant
it doesn't qualify as a true atrial septal defect
the foramen is functionally closed b/c LA P >RA P followed by anatomical closure
What are the potential post-natal consequences of an atrial septal defect?
●excessive blood flow from LA to RA → volume overload on RV → dilation and eccentric hypertrophy eventually

●both RA and LA may dilate dt volume overload

●if the shunt reverses dt development of sufficient pulmonary hypertension, cyanosis occurs
What are the potential post-natal consequences of a ventricular septal defect?
●small shunt → clinically insignificant

●RV faces a pressure overload and a volume overload → hypertrophy

●LA & LV also face a volume overload dt extra blood volume reurning from lungs → dilation & LV hypertrophy

●if reverse shunt occur, cyanosis
What is meant by the term tetralogy of Fallot?
a congenital heart defect which classically has four anatomical components
●VSD -located high in IV septum
●pulmonic stenosis
●overriding aorta
●compensatory concentric hypertrophy of RV dt pressure overload (2ndary)
What are the consequences of tetralogy of Fallot?
RV outflow obstruction
clinical sings of rapid fatigue, retarded growth rate, cyanosis, and polycythaemia
What are the consequences of pulmonic stenosis? In which species is this most commonly seen?
-pressure overload on RV → concentric hypertrophy

-high veloity and turbulent blood flow → post-stenotic dilation of pulmonary artery

*common in dogs, unusual in other spp
What are the consequences of subaortic stenosis? In which species is this anomaly common?
-pressure overload on LV → concentric hypertrophy

-post-stenotic dilation of aorta

-oftern arrhythmias and sudden death

-low systemic blood pressure → syncope

-impaired RV filling dt LV hypertrophy

*common in pigs & dogs
What are the consequences of mitral or tricuspid valve dysplasia?
commonly cause valve insufficiency (can also be stenosis)

tricuspid insufficiency → volume overload on RV and RA → dilation → R-sided CHF in young

-mitral insuff → volume overload on LV & LA → dilation and LV eccentric hypertrophy → L-sided congestive heart failure in young animals
What are the possible defects associated with abnormal development of endocardial cushions? In which species are endocardial cushiion defects common?
endocardial cushion defects → high VSD, low ASD, tricuspid or mitral dysplasia or a common atrioventricular canal

common in pigs & cats
What is meant by an overriding aorta (=dextropositioned aorta)?
transposition of aorta so that aorta straddles the IV septum and receives blood from botrh RV and LV → pulmonary artery derains the RV as per normal
What is the usual clinical manifestation of a persistent right aortic arch in a dog and why?
ligamentum arteriosum traps the oesophagus and compresses it against the trachea, leading to oesophageal obstruction → regurgitation and megaoesophagus

dt persistence of the right fourth aortic arch rather than the normal left fourth aortic arch
In which spp are congenital haemocysts common? What are these lesions and what is their significance?
common on margins of A-V valves, esp in calves

it's blood filled cysts lined by endothelium (usually regress in first few months of life)

usually asymptomatic
What is meant by the term brown atrophy of the heart? In which spp is it most commonly seen and in what circumstances?
= gross brown discolouration of the myocardium dt accumulation of golden-brown lipofuscin pigment in myofibres b/c of chronic wasting disorders and malnutrition

expecially seen in Ayrhire cattle
What are the most common causes of myocardial degeneration in domestic animals?
many systemic disease, esp anaemias, toxaemias, and systemic febrile infections

bacteriaemias

nutritional deficiency
What would be your differential diagnosis of you observed myocardial mineralisation in an animal at necropsy?
chalkiy white mineralisation → white muscle disease in cattle and sheep, hypervitaminosis D, vitamin D anologue poisoning

Selective calcium deposition on necrotic Purkinje fibres → organomercurial poisoning in cattle
List 10 possible causes of myocardial necrosis in domestic animals
Infectious agents (foot & mouthu disease virus, canine distemper virus in puppies)

Ischaemia

Physical injuries & shock (CNS lesions and trauma, stress, overexertion)

Nutritional deficiencies (Vit E/selenium, thismine, copper, K, Mg, Cl)

Toxicity (Cobalt, Histamine, Vit D, NaCl etc)

Plants

Metabolic (uraemia, porcine stress syndrome etc)

Miscellaneous (duchenne muscular dystrophy)
How long must the patient survival period be before lesions of myocaardial necrosis beome grossly visible?
18 hours
How are foci of myocardial necrosis repaired?
infiltrated by neutrophils and macrophages, then replaced by fibroplasia leading to productiono fo mature scar tissue
What is white muscle disease?
White muscle disease (WMD) is a degenerative muscle disease found in all large animals. It is caused by a deficiency of selenium and/or vitamin E which are antagonists of free raducals
What gross lesions woulg you expect ot find in a lamb that has died from white muscle disease?
-pale, flabby muscles with poor development of rigor

-widespread shalky white mineralisation

-damage in mjor muscles of shoulder, thigh, back , neck and respiratory muscles

-congenital lesions, most advanced in tougue and neck muscles
What is mulberry heart disease?
A common form of vitamin E/selenium deficiency in pigs, usually manifested by sudden death, or by dyspnea, cyanosis and recumbency. Extensive subepicardial hemorrhage gives the disease its name.
What are the major gross lesions that you would expect o find in a pig that has died from mulberry heart disease?
-cyanosis of ears and ventral abdomen
-orbital and palpebral oedema +/- intramuscular oedema
-pulmonary oedema and congestion
-congested liver +/- gall bladder wall oedema
-congestion of intestinal mesenteries
-heart with haemorrhages into epicardium, myocardium, and subendocardium
What is porcine stress syndrome?
= "back muscle necrosis" "transport death" "pale soft exudative pork" dt abnormal intracellular calcium homeostasis compounded by excessive catecholamine release

= spontaneous disease affecting malignant hyperthermia susceptible pigs when stressed
-affected animals have a deficiency of inositol 1,4,50triphosphate phosphatase
What is malignant hyperthermia?
= an acute procine stress syndrome in which various drugs such as halothane induce metabolic acidosis, pyrexia, muscle tremors, tachycardia, dyspnoea, muscular rigidity, skin blanching and erythema and high mortality
What clinical and gross post mortem findings might support a diagnosis of porcine stress syndrome in a pig?
-rapid development of rigor mortis

-pale soft wet skeletal muscles, esp of back , loin, shoulder and thigh

-+/- epi-and endocardial haemorrhages and blotchy myocardial pallor in LV

-pulmonary oedema

-hydropericardium

-splanchnic congestion

-stomach may be congested or harmorrhagic with fundic ulceration
What is meant by the term cardiomyophathy?
= idiopathic myocardial disease which is diagnosed by exclusion
What are the gross characteristics of a dilated cardiomyopathy? In which spp is this condition most commonly diagnosed?
prominent concentric hypertrophy of LV & IV septum which may be symmetric or asymmetric

myocardial contractility is usually increased or normal but diastolic filling of ventricules is decreased

common in cats
What are the gross characteristics of a dilated cardiomyopathy? In which spp is this condition omost commonly diagnosed?
*common in dogs

-decreased contractility, increased end-diastolic vol of ventricles and decreased ventricular ejection

-usually all chambers are dilated but LA and LV enlargement may be most obvious

-fabby and thin-walled heart
What is common consequences of carduintiogathy in cats? What clinical signs would alert you to this problems?
Hypertrophic cardiomyopathy is the most common!

occasionally dilated cardiomyopathy, and restrictive cardiomyopathy may be seen

Arterial thromboembolism can also occur
List 5 potential causes of myocarditis in domestic animals
-viral infection (canine parvovirus, canine distemper, foot & mouth disease etc)

-bacterial (baccilus piliformis, haemophilus somnus etc)

-protozoan (toxoplasma gondii etc)

-parasitic (cysticercosis, trichinosis)
Name three parasites that can cause myocarditis in domestic animals
-Sarcocystis spp

-Cysticercosis: Taenia ovis, Taenia saginata, Taenia solium

-Trichinosis: Trichinella spiralis