After 17 long years at the Phoenix Zoo, Sierra the mountain lion was humanely euthanized after experiencing renal failure, the zoo said on Feb. 27. She came to the zoo 17 years ago as an orphaned cub ...

Zoo staff made the difficult choice to euthanize one of the zoo’s two female mountain lions, Sierra, earlier in the week.

The zoo said zookeepers and veterinary staff made the "difficult decision" to put down mountain lion Sierra earlier this week ...