BOSTON (AP) – Veterinarians at the Franklin Park Zoo are treating an ailing lion for kidney failure, but the life-threatening condition appears to be growing worse, a zoo spokeswoman said Sunday.

Cliff, one of two lions on display at the Kalahari Kingdom exhibit, may have only a few more weeks to live if his condition continues to deteriorate, Zoo New England spokeswoman Melissa Grossenbacher.

“It’s not looking good,” she said.

In early June, veterinarians noticed that the 12-year-old lion appeared lethargic and wasn’t eating. Tests performed on June 18 ruled out a number of infectious diseases, but couldn’t pinpoint the origins of his kidney failure.

“When they’re sick, it’s really hard to tell because they try to cover it up as much as possible,” Grossenbacher said.

The average life span of a lion is about 17 years, Grossenbacher said. Kidney failure is one of the leading causes of death for all cats. “Even the big ones,” she added.

Cliff was born in captivity and came to Boston from Florida in 2001. The zoo says Cliff will be seen at the exhibit as long as his health permits it.

Dr. Eric Baitchman, Zoo New England’s associate veterinarian, said the zoo is treating Cliff’s symptoms to keep him as comfortable as possible.

“At this rate, he probably only has a few weeks to months left to live, but we keep hoping he’ll surprise us and pull through,” Baitchman said in a statement.

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