Pathologic and cardiovascular characterization of pheochromocytoma-associated cardiomyopathy in dogs.

Pheochromocytoma-associated catecholamine-induced cardiomyopathy is a well-known entity in man, nonhuman primates, and mice but has not been described in dogs. In this retrospective study, 9 dogs were identified with pheochromocytomas and concurrent cardiovascular pathology observed histologically (n = 6), echocardiographically (n = 4), and/or electrocardiographically (n = 5). Cardiac lesions included multifocal cardiomyocyte necrosis with contraction bands, cardiomyocyte degeneration, myocardial hemorrhage, lymphohistiocytic myocarditis, and interstitial fibrosis. Clinical procedures, including electrocardiographic and echocardiographic examinations, Doppler blood pressure measurement, and auscultation, were available for 5 dogs and consistently revealed concentric or mixed (eccentric and concentric) ventricular hypertrophy. Additional changes observed included arrhythmias, systemic hypertension, and heart murmurs. The myocardial lesions observed in this series of dogs are similar to those observed in humans with pheochromocytoma-associated catecholamine-induced cardiomyopathy. Since the clinical manifestations of catecholamine-induced cardiac disease are amenable to medical treatment, recognition of this cardiomyopathy has the potential to reduce morbidity and mortality in dogs with pheochromocytoma.