CINCINNATI (WJW) — The Cincinnati Zoo & Botanical Garden is mourning the loss of one of its furry friends Saturday.

Little One the geriatric polar bear was “humanely euthanized” Saturday morning following renal failure, the zoo announced.

“Over my 30 plus year career, I’ve had the privilege of caring for 17 polar bears in two zoos. All of them have been amazing animals to care for,” the zoo’s head bear keeper Lisa Vollmer said in a statement. “Saying goodbye is always hard, and it was especially hard with Little One. He was one of the most easy going bears I’ve ever worked with and had a great disposition.”

Staff had recently noticed that Little One was not as interested in his usual activities like snacking on peanut butter, swimming and napping. So the zoo veterinarians ran a battery of tests and discovered the renal issue.

Little One was reportedly the second oldest polar bear living in captivity in the United States when he died. A male polar bear’s median life expectancy is 21 years old.

The bear was born at the Cleveland Metroparks Zoo in 1989 to Snowball and Nauyat. He came to Cincinnati in 2007.

“His passing leaves a huge hole in hearts of all of us who cared for him,” Vollmer said. “Rest in peace Little One. We love you and you will be missed.”