Veterinarians at the Calgary Zoo were forced to put down one of its most beloved gorillas last week, a death that has sparked debate over whether the animals should be held captive at all.

Donge, a 22-year-old western lowland gorilla that had been at the zoo since she was three years old, was put to sleep Friday. She had been suffering from an inflammatory intestinal disease, called diverticulitis, for years and never quite recovered from her last surgery.

"From the last surgery she had probably ten days ago now, she was not bouncing back and her condition worsened," Garth Irvine, the zoo's gorilla keeper, told CTV Calgary on Monday. "It was a struggle to get medications into her and a struggle to get food into her, she just continued to get worse."

Donge is the fourth gorilla from the troop that has died over the past year from disease. Tabitha, a 27-year-old gorilla, died after suffering a seizure in April. Then, a month later 37-year-old Julia died from severe liver disease. Last year, a baby gorilla born at the zoo died when it was just 12 days old.

Rob Laidlaw, executive director at Zoocheck Canada, said the remaining three gorillas in the troop should be released from the Calgary Zoo, as the animals generally don't do well in a zoo setting.

"I think one needs to look no further than the extremely small space, the hard surfaces, the electrified bushes and the fancy backdrops to realize just how inappropriate it is for gorillas," he told CTV Calgary.

But Irvine refuted those suggestions, and said the zoo participates in an endangered species program that helps keep healthy blood lines alive.

"She did pass along her genes to the captive North American gene pool. She has one son living at the Granby Zoo (in Quebec)," he said. "It is all part of the international endangered species program we are proud to be a part of it."