Cardiovascular Diseases in Large Animals

Question 1

Ventral Septal Defect (VSD)

Answer 1

Most common congenital cardiac defect in large animal
Opening in the ventricular septum (high membrane)

Question 2

What is VSD caused by?

Answer 2

Failure of fusion between endocardial cushion and muscular part of the septum or between truncal septum and concal septum

Question 3

Pathophysiology of VSD

Answer 3

L to R shunt between LV and RV causes volume overload of RV → pulmonary hypertension and dilation of RV and LA → LV fails from chr. volume overload → congenital heart failure , excessive turbulence, endocarditis, and aortic regurg

Question 4

Cs of VSD

Answer 4

Pansystolic murmurs
Palpable cardiac thrill
Poor growth, leth., dyspnea

Question 5

Diagnosis of VSD

Answer 5

Clin path: polycythemia
Rads: cardiomegaly, lung vascularization

Question 6

Patent Ductus Arteriosus (PDA)

Answer 6

Connects the pulmonary artery and aorta
Single defect or a complex anomaly

Question 7

Pathophysiology of PDA

Answer 7

L. to R. shunt from aorta to pulmonary artery →↑ the volume load on the RV → RV fails or dilates and hypertrophies → pulm. hypertension and congestion

Question 8

CS of PDA

Answer 8

Leth, dyspnea, exercise intolerance and CHF
Continuous murmur (high pitch and of alt intensity)

Question 9

TX of PDA

Answer 9

Sx in neonates
Small PDA asymptomatic, large= poor prog

Question 9

DX of PDA

Answer 9

Angiocardiography

Question 10

Tetralogy of Fallot

Answer 10

1. Over-riding aorta
2. VSD
3. Pulmonic stenosis with obstruction of pulm. arterial flow
4. RV hypertrophy due to obstruction of pulm. arterial flow
   Pentaology= 5. atriall septal defect

Question 11

What is tetralogy of fallot caused by?

Answer 11

Abnormal development of the conal septum in the embryonic heart
More common calves than foals

Question 12

Pathophysiology of tetralogy of fallot

Answer 12

Obstruction → severely reduced pulm. circulation → severe cyanosis

Question 13

CS of tetralogy of fallot

Answer 13

Cyanosis of mm, nose and skin
Exercise intolerance, slow or stunted growth
Loud pansystolic murmur (crescendo-decrescendo or plateau shaped), palpable thrill

Question 14

Dx of tetralogy of fallot

Answer 14

Echo
Clin Path: ↑ PCV and RBC count from polycythemia
Poor prog

Question 15

Atrial fibrillation

Answer 15

Cardiac dysrhythmia by lack of coordinated atrial electrical activity

Question 16

Causes of atrial fibrillation

Answer 16

Abnormal impulse condition due to uni-directional conduction block and random re-entrant activation of atria
Atrial enlargement due to myocarditis
Electrolyte or acid-base imbalance, anesthetic drugs or AV valve regurg

Question 17

Where is atrial fibrillation commonly seen?

Answer 17

Dairy cattle more than beef
GI dz/ abdominal pain, footrot or pneumonia in cattle
Horses due to high resting vagal tone (standardbred, thoroughbred, draft horses)

Question 18

Pathophysiology of atrial fibrillation

Answer 18

Atrial contraction not coordinated → ventricular filling more passive → reduce blood flow to other organs → ↓ milk production, GI motility and colic

Question 19

Pathophysiology of chr. atrial fibrillation

Answer 19

Progressive cardiac dz (fibrosis due to reduced myocardial blood flow)

Question 20

CS of atrial fibrillation

Answer 20

Asymptomatic @ rest
Anorexia, ↓ milk production in cattle
Exercise intolerance, poor performance and colic in horses

Question 21

DX atrial fibrillation

Answer 21

CS
Clin path: met alk. due to GI dz, ↓ Ca, K and Cl
Electrocardiography: Irreg R-R interval, absent P waves replaced by fine undulation of baseline (f waves)

Question 22

Tx for atrial fibrillation

Answer 22

Quinidine in cattle and horses (beg ionotrope) → make sure animal is hydrated with norm acid-base levels `

Question 23

Ventricular tachycardia

Answer 23

Cardiac dysrhythmia characterized by a rapid rhythm originating in the ventricle below the bundle of His

Question 24

What causes ventricular tachycardia

Answer 24

Disorder in impulse formation or conduction due to myocarditis, fibrosis, bacterial endocarditis, ischemia, and hypoxia, etc

Question 25

________________ may be the leading cause of sudden death in horses and reported in all large animals

Answer 25

Ventricular tachycardia

Question 26

CS of ventricular tachycardia

Answer 26

Asymptomatic @ rest
Exercise intolerance, severe CHF, pulm. edema, resp. distress, coughing, ventral edema
Rapid HR with irreg or reg rhythm
Jug pulses

Question 27

What is ventricular tachycardia secondary to in cattle?

Answer 27

Sepsis and toxemia with signs of anorexia and ↓ milk production

Question 28

Dx of ventricular tachycardia

Answer 28

ECG: series of 4 or more ventricular premature depolarizations (ventricular complex)
QRS larger and longer than normal

Question 29

TX of ventricular tachycardia

Answer 29

Correcting primary dz or electrolyte imbalance
Severe CHF or rate of ven trachy high: Lidocaine and Mg. sulfate in bovine

Question 30

What is the most common atrial septic defect

Answer 30

Ostium secundum defect (patent foramen ovale):
O secundum- opening in high septum primum of embryonic heart where foramen will be
O. primum- opening low in the septum primum where AV valve will be

Question 31

Where is patent forman ovale common?

Answer 31

Calves (associated with PDA)

Question 32

What is patent foramen ovale caused by?

Answer 32

Failure of the septum primum to adhere to the crista dividens and close the foramen after birth

Question 33

CS of patent foramen ovale

Answer 33

Often asymptomatic
Holosystic crescendo-decrescendo murmur @ left heart base
Enlarged RA, dilation of LA and RV

Question 34

Dx of patent foramen ovale

Answer 34

Echo will visualize enlarged RA, LA, RV and defect