Feline cardiomyopathy.

Cardiology was diagnosed by means of clinical, radiographic, electrocardiographic phonocardiographic, angiocardiographic, and pathological findings in 271 or 3,745 cats necropsied from January 1962 to April 1974. The affected cats can be divided into three groups on the basis of the gross and microscopic pathological lesions: 1)endocarditis and myocarditis in 20 young cats; 2)endomyocardial fibrosis and left ventricular hypertrophy in 182 cats; and 3)myocardial degeneration and biventricular dilatation in 69 cats. Of 271 affected cats, thromboembolus was observed in the aorta, and in the carotid, femoral, iliac, renal, pulmonary, and hepatic arteries in 104 instances. The important aspects of cardiomyopathy in cats appears to be the reduced diastolic compliance of the thick left ventricle, resulting in poor fillin. Resistance to ventricular inflow raises the diastolic pressure and causes compensatory left atrial enlargement. A pathogenesis for the onset of clinical signs at any stages as the cause of the heart disease is postulated on the basis of stress causing tachycardia and poor left ventricular filling. Acute left-sided failure with pulmonary edema may be precipitated. Approximately one-fourth of the cats have enlargement of all cardiac chambers, typical of congestive cardiomyopathy. On the basis of the close similarily to cardiomyopathy in man, the cat could serve as a suitable animal model for a conservation of time and effort in the attack against this disorder. There is a need for coordinated research programs for utilizing the multiple avenues of approach such as: epidemiological, clinical, biochemical, pathological, ultrastructural, virological, and immunological.