Yukon,1981-2009 a brown bear who has entertained visitors to the Tulsa Zoo for more than two decades, was euthanized Thursday due to an untreatable cancer, officials said. Yukon’s recent behavior changes prompted zoo veterinary staff to conduct an emergency medical exam, according to a zoo press release. After discovering signs of inoperable liver disease, veterinary staff decided to euthanize the 28-year-old male bear. “From the physical exam and ultrasound scan of his abdomen it was clear that his condition was severe and untreatable,” said zoo veterinarian Kay Backues. Further test results confirmed the diagnosis of cancer. Bears can live as long as 25 to 30 years in the wild, 30 to 40 years in captivity, if they remain in good health. Many zoo animals are living longer lives and facing the health issues of old age, according to the zoo. “Liver disease, and especially liver cancer, are common in geriatric bears of all species,” Backues said. Yukon first arrived at the zoo in 1985 from Seattle’s Woodland Park Zoo, where he was born in 1981. He had a well-loved personality and many fans. His enormous size — 1,440 pounds — gave visitors an impressive reason to visit the south end of the park, zoo officials said. The zoo has received condolences from visitors including one woman who said “he was truly an amazing, awesome and handsome bear. He will truly be missed by everyone that visits the zoo.” Zoo staff are also feeling the loss. “I’ve known Yukon for 24 years, it was a privilege and pleasure to have him here in Tulsa for all to enjoy,” said Karen Dunn, large mammal curator whose department oversaw the bear’s daily care. Amy Pierce, large mammal keeper, worked with Yukon for the last three years. “I miss his presence, he was personable for a bear his size,” Pierce said. Yukon loved his enrichment items, especially a 50-gallon barrel with holes in it that was filled with fruit and vegetables that he would have to maneuver to get out. Dunn recalled a zoo member night where Yukon was featured. “After about an hour of guests watching him, he got tired and let a loud sigh and then rolled over with his back to everyone and put his paws over his face,” she said. “I think he was letting us know we were disturbing his quiet time.” The zoo has a 28-year-old female brown bear, Lil Sis, who is not on exhibit because of her arthritis, which is common for a bear her size and age, zoo officials said. The zoo has no plans to obtain another brown bear and will not replace Lil Sis when she dies. The current exhibit is in need of modifications in order to safely house a younger bear collection. The exhibit will be used to shift other species of bear that are on exhibit elsewhere.