Abstract
Two cases of hypertrophic cardiomyopathy in Holstein dairy cows are presented. At necropsy, the hearts revealed proportionate hypertrophy of the entire ventricles. The cut surface showed relatively large areas of myocardial scarring scattered throughout the ventricular walls including the septum. Microscopic examination revealed marked disorganization of cardiac muscle cells, intramural coronary arteries with thickened walls and narrowed lumina, and pronounced myocardial fibrosis. These features resemble those of hypertrophic cardiomyopathy in humans, suggesting the presence of a similar primary myocardial disease in cattle.
