Chapter 49 - myocarditis

Question 1

4 potential viral causes of myocarditis?

Answer 1

parvovirus
canine adenovirus type 1
distemper virus
west nile virus

Question 2

Chagas’ disease occurs most commonly in which two US states?

Answer 2

Texas

Louisiana

Question 3

Dogs with chronic Chagas’ typically present in left-sided heart failure. T/F?

Answer 3

F - acute usually right-sided CHF (see trypomastigotes on blood smears), chronic usually neurological damage (ataxia, weakness)

Question 4

Which of the following statements are true regarding myocarditis?

a. The most common agents are Staphylococcus spp and Citrobacter spp.
b. Lyme disease (Borrelia) is a common cause in dogs
c. Bartonella causes endocarditis, concurrent myocarditis is exceedingly rare
d. Fungal myocarditis has been reported in veterinary patients

Answer 4

a. most common are staph & strep
b. Lyme myocarditis is rare in dogs
c. Bartonella myocarditis was noted in 2/12 dogs with endocarditis
d. TRUE - very rare

Question 5

List 3rickettsial causes of myocarditis in dogs

Answer 5

Rickettsia rickettsii (RMSF)
Ehrlichia canis
Bartonella spp.

Question 6

List 3 parasitic causes of myocarditis

Answer 6

Toxoplasma gondii
Neopsora caninum
Trichinella spiralis

Question 7

List features of doxorubicin cardiotoxicity

Answer 7

Irreversible
Dose dependant (more common >250mg/m2)
arrhythmias, myocardial failure or both
time to onset of CHF is highly variable
clinical syndrome hasn't been reported in cats (although myocardial pathology has been seen)

Question 8

Why should digoxin be used with caution in myocarditis?

Answer 8

increased expression of pro inflammatory cytokines and increased mortality in experimental myocarditis in a murine model

Question 9

Alternative considerations for systolic dysfunction?

Answer 9

dobutamine, pimobendan (also reduces after load)

Question 10

What is the consensus regarding NSAIDs for myocarditis?

Answer 10

can worsen myocardial damage in the first 2 weeks in humans, appear safe later in the course of disease

Question 11

Role of immunosuppressants for myocarditis?

Answer 11

Only for systemic autoimmune disease, otherwise not routinely helpful

Question 12

Empiric treatments for:

a. toxoplasmosis
b. rickettsial disease
c. bacteremia
d. signs of CHF

Answer 12

a. clindamycin
b. doxycycline
c. a/bs effective against staph & strep
d. diuretics, ACE inhibitors

Question 13

List features suggestion of myocarditis

Answer 13

history suggestive (doxorubicin, lives in Texas etc)
unusual signalment for heart disease (GSD, irish setter etc)
ECG findings (conduction abnormalities, arrhythmias)
echo findings (myocardial dysfunction - global/focal +/- enlargement)
lab findings suggestive (leukocytosis, eosinophilia, elevated cardiac troponin I levels)