The B.C. SPCA has launched an investigation after the death of four zebras at the Greater Vancouver Zoo.

The animals died in early March after several cape buffalos were introduced into their enclosure.

Peter Fricker, a spokesperson for the Vancouver Humane Society, said the animals died of exertional myopathy, a stress-related condition where an animal's large muscle groups are overexerted to lethal levels.

"When the two cape buffalos were introduced into the enclosure the zebras started running around in circles and didn't stop," he said.

"For some reason the zebras were spooked by buffalos and perceived them as predators - and they panicked," Fricker said.

Eileen Dreever of the B.C. SPCA says the condition is usually fatal, most often resulting in renal or heart failure.

"One died within hours and the other three died within a few days of that."

Fricker said zoos normally introduce new animals into an enclosure to maximize space or try to replicate conditions in the wild, but the zoo made a mistake by trying to get the zebras and buffalo to co-exist.

"In the natural environment there is an escape route, you can stay in your own territory and there's no need for conflict," he said.

"But this isn't a wild area and in our view the animals shouldn't have been introduced at all or it should have been done more carefully."

Dreever said the SPCA investigation will look at why the buffalos remained in the enclosure after one zebra had already died.

"Did they remove the zebras from the situation or have a back up plan?" Dreever said. "These are the questions we need to ask. If these animals are so stressed out they're hitting the fences, there's a problem."

Patterns of problems

The recent death of the zebras has once again raised questions about care and management at the Greater Vancouver Zoo.

"This seems to be an ongoing problem with conditions and the death of animals," said Fricker.

The Vancouver Humane Society is calling for an investigation of the facility's accreditation.

The facility was questioned by the SPCA after a baby female giraffe born at the facility in 2006 died after only eight days.

That same year, the zoo was charged under the B.C. Prevention of Cruelty to Animals Act in relation to the mistreatment of a two-year-old hippopotamus named Hazina. The SPCA charged the animal was not being provided with basic standards of care provided by the American Zoo and Aquarium Association.

The hippo, which had outgrown her pool, was held for 15 months in a concrete holding pen with no access to the outdoors after she was acquired from a Quebec zoo, according to Dreever.

The charges were stayed because the hippo was moved to a new enclosure.

In 2003, a 4,100-kilogram elephant named Tina developed health problems at the zoo, but was transferred to an elephant sanctuary in Tennessee for better treatment. She died in 2004.

Most recently, a spider monkey named Jocko was killed during a break in to the facility. Jocko's partner of more than 15 years, a female monkey, Mia, was stolen.

The zoo is holding a press conference Tuesday afternoon.