Feline Cardiomyopathy

Feline cardiomyopathy is any disease of the myocardium associated with cardiac dysfunction. Hypertrophic cardiomyopathy (HCM) is the most common feline cardiac disease, characterized by enlargement of the left ventricular free wall, interventricular septum, or both. Restrictive cardiomyopathy (RCM) is characterized by myocardial stiffness and diastolic dysfunction and comprises about 20% of referred cardiac feline patients. Dilated cardiomyopathy (DCM) involves a severely dilated left ventricular chamber and hypocontractile myocardium and has been historically associated with taurine deficiency. Cats are diagnosed with unclassified cardiomyopathy if echocardiographic findings are not typical of commonly recognized cardiomyopathies.

Heart murmurs are thought to be present in 60% of all cats with cardiomyopathy. Other signs may include gallop sounds, muffled heart sounds, tachypnea, limb paresis, arrhythmias, arterial hypotension, and ascites. Diagnosis is made through imaging, electrocardiography, and blood pressure measurement. Biomarkers and genetic testing are a consideration for cats at risk for HCM.

Other than treatment for taurine deficiency, no therapies show consistent promise in the prevention or treatment of asymptomatic cardiomyopathy. Prognosis depends on the form of myocardial damage, severity, and rate of progression. Further controlled and blinded studies are needed to ascertain treatment efficacy in cats with cardiomyopathy.

CommentaryThis review described the phenotypic variations of feline cardiomyopathies, their diagnostic features, and the difficulty that can arise in defining a particular cardiomyopathy in a feline patient as well as how echocardiographic features of different cardiomyopathies can overlap at various stages of the disease process. In addition, current therapeutic strategies are aimed at combating the underlying pathophysiology and clinical presentation instead of focusing on treatment based solely on the type of cardiomyopathy diagnosed. This is an important concept to keep in mind for treating cats with cardiomyopathy, as the disease process will invariably evolve and change through the disease course and treatment needs to be modified and tailored accordingly.—Amara Estrada, DVM, DACVIM (Cardiology)

SourceFeline cardiomyopathy. Ferasin L. IN PRACT 34:204-213, 2012.