A 9-year-old apparently healthy male African wild dog (Lycaon pictus) was found dead in its enclosure at the De Wildt Cheetah and Wildlife Centre. Necropsy revealed a pericardium distended by approximately 250 ml of thick blood. A soft, red, lobulated mass was attached to the periaortic fat between the level of the aortic valves and the pericardial reflection. Histologically, the mass was consistent with a haemangiosarcoma. Other findings in the heart included mild to moderate ventricular hypertrophy and moderate, acute perivascular myocardial necrosis. Sudden death was attributed to acute heart failure precipitated by cardiac tamponade.