ECHOCARDIOGRAPHIC EVALUATION OF CAPTIVE BORNEAN (PONGO PYGMAEUS), SUMATRAN (PONGO ABELII) AND HYBRID ORANGUTANS (PONGO SPECIES).

Cardiac diseases in great apes are frequently diagnosed late in their life or at postmortem. Echocardiography allows early detection and diagnosis of heart diseases in great apes. Between January 2018 and October 2019, Mandai Wildlife Group (MWG) conducted health evaluations on 22 captive orangutans, including 10 Bornean orangutans (Pongo pygmaeus), eight Sumatran orangutans (Pongo abelii), and four hybrid orangutans (Pongo spp.). Fourteen male and eight female orangutans were evaluated. Cardiac assessment was conducted in partnership with the Great Ape Heart Project (GAHP). Subjects were anesthetized with either tiletamine/zolazepam intramuscularly or a combination of tiletamine/zolazepam and medetomidine intramuscularly followed by ketamine intravenously. All patients were intubated and maintained on isoflurane gas anesthesia. Trans-thoracic echocardiography (TTE) was completed according to the standards established by the Great Ape Heart Project. Noninvasive systemic blood pressure (NIBP) and 12-lead electrocardiogram (ECG) were conducted on all the orangutans. Of the 22 subjects evaluated, 18 had echocardiogram within an expected range. One adult male hybrid and one adult male Bornean orangutan have low fractional shortening (FS) because of the effect of medetomidine in the anesthetic protocol. One adult male Sumatran orangutan was diagnosed with mild left ventricle dysfunction and treated with enalapril 0.1 mg/kg PO SID. One adult female hybrid orangutan was diagnosed with an aortic aneurysm of the ascending aorta. Regular cardiac assessment in orangutans allows early detection of heart disease and enables proactive prevention of heart failure. The study also provided preliminary data establishing heart parameters for the two orangutan species and their hybrids.