Page 202 - Feline Cardiology

17

Miscellaneous Myocardial Disease

Key Points

• Myocarditis is an uncommon myocardial disease in the cat and the clinical importance likely depends on the underlying
etiology.
• Endocardial fibroelastosis is an uncommon endomyocardial disorder observed in young cats (usually <6 months of age) and
carries a poor prognosis. Burmese and Siamese cats appear to be predisposed.
• Excessive moderator bands can be observed in the left ventricle in cats of a wide age range. The clinical importance of them is
not well understood.

MYOCARDITIS Streptococcus canis myocarditis was reported in two
cats. In 1 case, the cat died shortly after a diagnosis of
Myocarditis is a rare form of myocardial disease charac- lameness (Sura et al. 2008). At necropsy bacteria were
terized by the presence of myocardial necrosis and/or identified in the myocardium, lungs, kidneys, brain, sub-
degeneration and inflammation. In the cat, infectious cutaneous tissue, and biceps femoris. In a separate case,
agents are most likely to be the etiology and can lead to an 11-year-old cat was diagnosed with mitral valve
damage to the myocardium and the induction of the endocarditis and myocarditis (Matsuu et al. 2007). At
inflammatory response. Chamber enlargement, myocar- necropsy, Streptococcus canis was isolated.
dial dysfunction, and arrhythmias can develop. Lymphoplasmacytic myocarditis was observed in
eight cats that were experimentally infected with
Bartonella; however, clinical signs suggestive of cardiac
Etiology, Pathophysiology, and disease were not observed (Kordick et al. 1999).
Gross Pathology
Therefore, the clinical importance of this finding is
Etiology unknown.
Toxoplasmosis has been reported to be a cause of myo-
carditis in both human beings and cats (Dubey and Pathophysiology
Carpenter 1993; Kirchhoff et al. 2004; Simpson et al. The presence of inflammation, myocardial necrosis, and
2005). In one report a cat with presumed toxoplasmosis degeneration can lead to systolic and/or diastolic dys-
myocarditis had elevated IgG and IgM titers to function, ventricular and atrial dilation, and the devel-
Toxoplasma gondii (Simpson et al. 2005). The cat pre- opment of both tachyarrhythmias and bradyarrhythmias.
sented for dyspnea, and a heart murmur was identified. Myocardial fibrosis may also develop.
Echocardiography demonstrated pericardial effusion
and increased echogenicity and hypertrophy of the myo- Pathology
cardium with both left and right ventricular involve- Myocarditis is a pathologic diagnosis that requires his-
ment. Treatment with clindamycin was initiated and topathological identification of inflammation, necrosis,
echocardiographic changes and clinical signs resolved. and fibrosis.

Feline Cardiology, First Edition. Etienne Côté, Kristin A. MacDonald, Kathryn M. Meurs, Meg M. Sleeper.
© 2011 John Wiley & Sons, Inc. Published 2011 by John Wiley & Sons, Inc.

205