BOISE -- Zoo Boise announced Thursday that Tundra, the zoo's 18-year-old Amur tiger, was euthanized earlier this week.
The big cat's health had been declining and he was not responding to veterinarian treatment, according to zoo officials. Signs of cancer in his liver and pancreas were found after he was put down Monday.
“Everyone at Zoo Boise is very sad about the passing of Tundra," Director Steve Burns said in a statement. "He was part of our family and we will miss him. An entire generation of children in the Treasure Valley grew up seeing him and marveling at his beauty and majesty."
Tundra and his brother Taiga came to Zoo Boise from Chicago's Lincoln Park Zoo in 1999.
Zoo officials say the life expectancy for Amur tigers - also known as Siberian tigers - is 16 years for males and 14.3 years for females in zoos. In the wild, the species typically lives ten to 15 years.
Amur tigers are endangered, and Zoo Boise says there are less than 3,200 of all tiger species left in the wild.
Zoo Boise is home to one other tiger, 12-year-old Katarina. The zoo will work with the Association of Zoos & Aquariums’ Species Survival Program to try to find a tiger to replace Tundra, but officials say it could take several months.
“Tigers are solitary animals, so Katarina will be fine for the next few months,” said Burns.