Canine Cardiomyopathies

Question 1

CS associated w/ CV disease

Answer 1

Exercise intolerance, syncope, breathing difficulty, abd distension

Question 2

Primary vs Secondary Cardiomyopathy

Answer 2

Primary:
functional impairment, electrical abnormalities, idiopathic, genetic
Secondary

Question 3

Most common breed for primary dilated cardiomyopathy

Answer 3

Dobermans
(PDK4 and titan genes)

Question 4

DCM pathophysiology

Answer 4

Heart dilates to normalize SV (compensatory mechanism)

Question 5

Compensatory chamber dilation on SV and EJ

Answer 5

Dilation will increase stroke volume but decrease injection fraction

Question 6

Costs of maladaptive hypertrophy

Answer 6

Neurohormones activated to augment filling can also cause hypertrophy, cell death, and fibrosis
Replacement or interstitial fibrosis (increased myocardial collagen): CT cells can proliferate while cardiomyocytes cannot

Question 7

Causes of secondary CMs with systolic dysfunction (DCM phenotype)

Answer 7

Nutritional/diet assoc.
Cardiotoxicities (doxorubicin > ROS)
tachycardiomyopathy
Myocarditis
Ischemic CM (coronary artery dz)
Endocrinopathies?

Question 8

Diagnosis of primary DCM

Answer 8

Echo: LV dilation + systolic dysfunction
+ Holter
Troponin (elevated)
NT-proBNT (elevated)

Question 9

Management of clinical DCM:

Answer 9

if CHF: furosemide, pimo, ACEi, spironolactone
Antiarrhythmics as needed (sotalol, amioderone)
A-fib: Diltiazem +/- digoxin
if 2: Diet change or underlying cause

Question 10

Prognosis of DCM:

Answer 10

Primary: poor long term
Bad clinical findings (poor prognosis):
< 5 yrs old + CS
CHF + ascites or pleural effusion
Frequent VPCs +CHF
A-fib + CHF

Question 11

Stages of arrhythmogenic right ventricular cardiomyopathy (Boxer DCH)

Answer 11

I: Asymptomatic w/ Ventricular arrhythmias
II: symptomatic w/ VA
III: LV systolic dysfunction/DCM phenotype (CHF + sudden death)

Question 12

Pathophysiology of ARVC

Answer 12

Abnormal desmosomes/ intercellular adhesions > tachyarrhythmias, impaired systolic function

Question 13

ARVC clininical recognition

Answer 13

Boxer or bulldog
Arrhythmia on PE
Syncope, exercise intolerance, lethargy, dyspnea, abd distention
Right sided VPCs

Question 14

Management of ARVC

Answer 14

Avoid strenuous exercise and excessive excitement
Antiarrhythmics
Pimobendan for type III + CHF tx if indicated

Question 15

Differentials for dogs w/ ventricular arrhythmias

Answer 15

HEADS
H: heart dz
E: electrolyte imbalance/endocrine dz
A: adrenergic tone/autonomic imbalance: stress/pain
D: drugs/toxins
S: surgical dz: splenic, GDV, pancreatitis etc