Luke, a 17-year old African lion at the Smithsonian National Zoo, was euthanized due to ongoing health problems.
CNN  — 

Luke, the patriarch of the Smithsonian National Zoo’s pride of African lions, has died at age 17.

The big cat was euthanized October 19, according to a news release from the zoo. He had experienced health problems for several years.

“Luke was truly the ‘king’ of the Great Cats exhibit,” said Craig Saffoe, one of the zoo’s curators, in the release. “He was gentle with his mates, Naba and Shera, and an extremely patient and protective father to all 13 of the cubs he sired.

“Luke has left a lasting legacy, not only in the cubs he contributed to his species’ survival, but also in the millions of visitors who were able to gain a deeper knowledge of and appreciation for African lions because of who he was as the patriarch of his pride.”

The lion had suffered “occasional discomfort and lameness in his right forelimb since 2016,” says the release. The veterinary team conducted a CT scan which found a lesion on his spine, but chose not to perform surgery due to the risk of complications. Instead, he received non-surgical treatment for his spinal problems, including steroids, oral medications, deep-tissue laser therapy, and acupuncture.

Earlier in October, zookeepers noticed at a routine weigh-in Luke had lost weight. During an exam October 19, they found cystic masses throughout his liver, and his spinal disease had progressed, causing several of his vertebra to fuse.

“Given these findings, Luke’s overall long-term quality of life was considered poor, and the animal care team decided to humanely euthanize him,” the zoo explained in the release.

Luke was born at a private reserve in South Africa in 2005, according to the release. He was considered especially valuable in the US “because his genes were not represented in US zoos” when he arrived in Washington, DC in 2006.

Visitors can still see one of Luke’s mates, Shera, alongside her offspring at the National Zoo.