A 15 year old, captive, female harbor seal was presented to the Veterinary Medical Teaching Hospital at the University of California, Davis in August of 1993. Clinical signs included severe depression, generalized weakness and inappetence. Physical examination revealed marked bradycardia, and weakness. All examinations and diagnostic procedures were performed without anesthesia or sedation. Diagnostic evaluation included a complete blood count (CBC) and blood chemistry panel, thoracic and abdominal radiographs, an electrocardiogram (ECG), and abdominal and cardiac ultrasound examinations.

CBC, chemistry panel, abdominal radiographs, and ECG were not diagnostic. Thoracic radiographs showed moderate cardiomegaly with bilateral atrial enlargement and pulmonary artery enlargement. Abdominal ultrasound showed hepatic vein dilation and caudal vena cave dilation with swirling spontaneous contrast, indicative of sluggish blood flow in these areas. Echocardiography showed marked dilation of the left ventricle (LV) and atrium (LV diastolic diameter 7.8 cm, LA/Ao ratio 2.2), feeble mitral valve motion, reduced LV systolic function (LV shortening fraction 13%), and marked spontaneous contrast in the left atrium and ventricle. Doppler echocardiography showed mild mitral valve regurgitation and physiologic pulmonary valve regurgitation. These findings indicated severe myocardial failure with signs of left and right heart failure. The seal died during a seizure approximately 8 hours following and ultrasound examinations. Necropsy examination showed meningoencephalitis, multifocal myocarditis, and hepatic and pulmonary venous congestion due to bilateral congestive heart failure.

Radiographic and ultrasound findings were characteristic of severe myocardial failure with markedly reduced stroke volume and clinical signs of low output failure. This case illustrates the application of 2D and Doppler echocardiography in cardiac evaluation in a marine mammal. Thoracic ultrasound has been used to help diagnose pulmonary problems in several marine species. A few species of marine mammals have been trained to tolerate diagnostic ultrasound examinations. Echocardiographic examination of normal animals during training, and the development of normal standards in these species, would greatly facilitate the examination of ill individuals and perhaps recognition of cardiac abnormalities early when therapy may prove more beneficial.