SALT LAKE CITY (AP) — A 14-year-old tiger has died at Salt Lake City's zoo.

The Hogle Zoo announced Friday that the Amur tiger named Kazek died after zookeepers witnessed rapid deterioration in his health.

The cause of death is still unclear. The zoo says an initial autopsy showed an inflamed gastrointestinal tract and a mass in his small intestine. He had been diagnosed with inflammatory bowel disease and was on a special diet to manage the illness.

Amur tigers are endangered and native to northeast Asia. The World Wildlife Fund estimates that there are only roughly 540 in the world.

Kazek was transferred to Salt Lake City from Buffalo in 2006.

The zoo says he had been a highlight for many guests and was considered an elderly animal roughly equivalent to an 80-year-old human.