Cardiovascular disease is being diagnosed with increasing regularity in captive gorillas and is a leading cause of mortality in this species. Regular cardiac evaluation can allow for early diagnosis and subsequent treatment, in order to attempt to slow or prevent disease progression.
In January 2007, a 23-year-old male gorilla was anesthetized in order to perform a complete cardiac evaluation, including transesophageal echocardiogram. Measurements in M-mode included left atrial diameter (4.03 cm), intraventricular septal thickness (1.87 cm), posterior wall thickness (2.3 cm), left ventricular end diastolic diameter (5.38 cm) and left ventricular end systolic diameter (3.47 cm). The ejection fraction was 44%. Color flow Doppler showed trivial mitral regurgitation, but no other valvular lesions. Brain natriuretic peptide (BNP) level was <20 pg/ml. Overall, the study was classified as abnormal, showing evidence of left ventricular hypertrophy, with mild to moderate left ventricular systolic impairment. Twice daily therapy with 50 mg carvedilol was initiated at this time. In November 2008, the patient was anesthetized for a second cardiac evaluation. An echocardiogram was performed with comparative measurements including left atrial diameter (3.2 cm), intraventricular septal thickness (2.1 cm), posterior wall thickness (2.1 cm), left ventricular end diastolic diameter (4.22 cm), and left ventricular end systolic diameter (2.5 cm). Ejection fraction was 58%. A dramatic improvement in ejection fraction and a significant reduction in most measurements were noted. BNP remained <20 pg/ml. Based on these findings, the patient’s carvedilol dosage was maintained and lisonopril was added at an increasing dose until a maintenance level of 40 mg twice daily was achieved. This patient concurrently receives levothyroxine and Zoloft. To date, no negative side effects have been noted to any medications. The findings in this case demonstrate the importance of early detection of cardiovascular disease in Western Lowland gorillas, as early treatment has the potential to slow and even reverse some changes associated with disease.