Fossey was father to Mosi, the first gorilla baby born at the Zoo in 2006, and Adelina, born in 2012. He was patriarch of the Zoo’s gorilla family which includes Sekani, mother of Mosi and Adelina, and Catherine, an adult female gorilla. Mosi was transferred in 2012 to the Lincoln Park Zoo to join a bachelor group of younger male gorillas. Adelina still lives at the Zoo.
Late Monday afternoon, Zoo staff observed Fossey chasing Sekani and Catherine between the indoor and outdoor holding areas of their exhibit. During warmer weather animals are given access to both areas. The chase continued inside when Fossey suddenly collapsed and died. While a full necropsy has yet to be performed, Zoo staff suspect that Fossey’s cardiovascular disease is to blame for his death.
Fossey had been diagnosed with cardiovascular disease in 2008 including severe mitral valve regurgitation and had a thickened left ventricular wall. He was started on medications to manage the disease including Enalapril and Furosemide. Fossey underwent annual echocardiograms and bloodwork. In 2013 Carvedilol was added to manage a new finding of moderate concentric hypertrophy, or thickening of the wall of the heart. Annual bloodwork showed that Fossey’s cardiovascular disease was being managed well. Fossey was under the care of a local cardiac technician who performed annual cardiac exams as well as a veterinary internal medicine specialist in addition to Zoo veterinary staff and keeper staff. Fossey’s next exam was scheduled for this month. He showed no outward signs of worsening cardiac disease.
Cardiovascular disease (CVD) is a significant cause of mortality in great apes, both in the wild and in captivity. There have been reports of heart disease in wild mountain gorillas with the most common pathology associated being fibrosing cardiomyopathy, aortic dissection, valvular disease, and ECG abnormalities. Cardiovascular disease occurs predominately in males in middle to older aged gorillas. Although atherosclerosis does occur in apes, it is most often an incidental finding. Clinical signs of cardiac disease are rare in apes, and sudden death is often the only sign. Median life expectancy for male western lowland gorillas is 31.1 years of age.
Fossey came to the Little Rock Zoo in 1993 from the Columbus Zoo in Ohio. Born in 1986, he was named after Dian Fossey, an American zoologist, primatologist, and anthropologist who undertook an extensive study of gorilla groups for more than two decades and is author of the book Gorillas in the Mist.