Winston, the oldest breeding male gorilla in the United States, is resting at the San Diego Zoo Safari Park after undergoing a thorough medical exam that included an in-depth assessment of his heart. The assessment was made after animal care staff noticed a decline in his general health earlier this year, when he showed nonspecific signs of illness, such as lethargy and decreased appetite. After an initial exam and supportive therapies, animal care professionals, in collaboration with colleagues from the Great Ape Heart Project, made the decision to perform a more in-depth analysis to determine the cause of his condition and afford him the opportunity to thrive with his troop for the foreseeable future. Along with experts from the University of California, San Diego; the University of California, Davis; the University of California Veterinary Medical Center, San Diego; and the Veterinary Specialty Hospital of San Diego, veterinarians placed the 45-year-old critically endangered gorilla under general anesthesia—allowing doctors the opportunity to perform multiple procedures, including a complete dental evaluation, x-rays with multiple radiographic images, laboratory tests and a cardiac evaluation, including electrocardiogram and echocardiogram. Doctors will now review their findings to determine the root cause of his symptoms, for example heart disease, a common condition seen in geriatric gorillas. “Our medical care for these animals has really advanced over the last 10 to 20 years,” said Lauren Howard, DVM, associate director of veterinary services at the San Diego Zoo Safari Park. “So, a lot of our animals are living longer than they used to—and with that comes age-related changes. And Winston’s no different.” Winston, one the world’s oldest breeding male gorillas in a managed care setting, arrived at the San Diego Zoo Safari Park in 1984 with five other gorillas. Animal care staff describe him as a strong silverback with a very easygoing personality—only getting involved in resolving disputes between members of his gorilla troop if he absolutely has to. Guests can typically spot Winston lounging in the rear of the exhibit or perched at either end of the habitat watching the other gorillas, especially the young males, to make sure they behave. Gorillas are listed as Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Threats to the species include people hunting gorillas for food, called bushmeat, loss of habitat due to logging and mining, and disease, such as Ebola. The past 15 years have seen a dramatic decline in gorilla numbers, with almost half of the entire eastern gorilla species population believed to have been wiped out. San Diego Zoo Global has partnered with multiple organizations and local conservationists in Uganda, Rwanda, the Democratic Republic of the Congo and Cameroon to shed light on gorilla genetic variations across regions, and to promote community-led conservation initiatives. The Safari Park’s Gorilla Forest is home to a troop of nine western lowland gorillas—Winston, four adult females, two young males, one young female and the newest addition, a female baby born last year.