CHICAGO (CBS) — Zenda, an African lion that would have turned 14 this July, has passed away at the Brookfield Zoo.

(Credit: Jim Schulz/Chicago Zoological Society)

According to the zoo, staff saw that Zenda was having trouble standing and walking. Over the last week, vets were treating his symptoms with medication to ease the animal’s pain. But on January 2, Zenda’s condition had declined dramatically and the decision was made to euthanize the lion.

(Credit: Jim Schulz/Chicago Zoological Society)

The Chicago Zoological Society said “preliminary necropsy results revealed Zenda had several degenerative discs in his spine that had ruptured as a result of his advanced age and were inoperable.”

Zenda came to the zoo in 2008, but over the years, the majestic lion began to lose his impressive mane but his loud roar could be heard from many places in the zoo.

(Credit: Jim Schulz/Chicago Zoological Society)

“He was incredibly protective of his mate, Isis, who also arrived that same year,” said the Chicago Zoological Society in a media release. “He could often be seen either grooming Isis or sleeping with a paw on her.”

(Credit: Jim/Schulz/Chicago Zoological Society)

The zoo said it will be working with and closely monitoring Isis, who will turn 15 this year, to help her adjust to the loss of Zenda.