Hypertrophic cardiomyopathy in a dog.

A 12-year-old spayed Corgi with heart failure did not respond to conventional medical therapy for congestive cardiomyopathy (furosemide, 2.5 mg/kg of body weight, IV, q 8 h; captopril 1 mg/kg, PO, q 8 h). Cardiac ultrasonography subsequently revealed a hypertrophic left ventricle and interventricular septum. Because a causative agent could not be identified, a diagnosis of primary hypertrophic cardiomyopathy was made. Administration of diltiazem (1.25 mg/kg, PO, q 12 h) resulted in sustained clinical improvement for several weeks. Complete cardiac evaluation, including echocardiography, was essential in determining the correct treatment for this dog.