Cheyenne Mountain Zoo said goodbye to one of its male Amur tigers, Ivan, on Wednesday after years of struggling to diagnose his medical issues.
The medications veterinarians had placed him on recently became ineffective. At that point, zoo officials said they knew they had exhausted medical options for Ivan and decided to euthanize him.
He was 10 years old.
Dr. Liza Dadone, a veterinarian and the zoo's vice president of mission and programs, said she suspects Ivan's medical issues were caused by cancer or an autoimmune condition.
Ivan was transferred to Cheyenne Mountain from the Sedgwick County Zoo in Kansas in 2016, where he had sired two cubs.
Ivan was known around the zoo as the "talker," making sure his feeders and zoo guests never forgot he was there.
"Ivan was somewhat stingy with his chuffs, but he was always vocal with huffs, grumbles and moans during feeding times, enrichment activities or when he just wanted to let you know he was there," animal care manager Dina Bredahl said.
The rare tiger was adopted by the zoo as part of the Species Survival Plan program. He was considered an ideal mate for a female Amur, Zoya, because of his massive size and genetic compatibility to her.
While mating in July 2016, Zoya received a cut to her neck that ultimately killed her. The incident was not entirely unusual, as tiger breeding in the wild often can become violent and lead to fatal fights.
Amur tigers are one of five subspecies of tigers still in existence. All five are threatened with extinction because of poachers, habitat destruction and loss of prey. Fewer than 500 Amur tigers exist in the wild.