Photo by Mehgan Murphy/Smithsonian National Zoo

Nikki, the National Zoo’s 20-year-old Andean bear, was euthanized yesterday after a losing battle with cancer, said the zoo in a statement:

Nikki developed an ulcer on his lower jaw in 2011. When keepers noticed that it was not healing, National Zoo veterinarians examined the bear and obtained a biopsy of the ulcer. The test results revealed that the ulcer was an aggressive squamous cell carcinoma, a type of cancer. Zoo veterinarians, with the help of consulting veterinary dental and surgical specialists, removed the affected section of Nikki’s jaw. Based on consultation with a veterinary oncologist, the bear was started on oral chemotherapy to slow any potential regrowth of the tumor. Nikki did well for a year. Unfortunately, the carcinoma spread to other areas of his body.

Nikki came to the zoo in 2007—he was severely overweight at the time, and lost 200 pounds in a single year—and sired two baby Andean bear cubs, Bernardo and Chaska, in early 2010. While Chaska remains at the zoo with mother Billie Jean, Bernardo was sent to Tulsa in April.

Andean bears tend to live between 20 and 25 years in the wild. Other animals that have been euthanized at the zoo over the years have included a 40-year-old elephant, a 30-year-old bald eagle, a 15-year-old gazzelle, and a 13-year-old cheetah.