Polar bear at Assiniboine Park Zoo died from trauma, vet says

Eli the polar bear died from swelling in his throat, but no one knows how he was injured.

The young bear died at Assiniboine Park Zoo on July 15 after acting "out of sorts"for a day or two then getting progressively worse, said Charlene Berkvens, associate zoo veterinarian.

"Eli was suddenly off food and lethargic or quiet for about 24 to 36 hours, and we started trying to figure out what the problem was," Berkvens said. "[We were]trying to put him on medications and decided that we should anesthetize him because he got a lot worse, and then he ended up passing away on us."

The zoo performed an autopsy on Eli andthey found neck tissue that was swollen enough to blockhis airways, she said.

"He would have passed away because he wouldn't have been able to properly breathe with all the swelling that was in his throat."

For the past two weeks, zoo staff have been combing video footage of the bear and have found no cause for his injury.

"There's three days of footage that we've been looking through," she said. "It is a mystery.We do know that most likely it was trauma that caused the lesion that we saw in his throat area with that swelling, but as to what exactly led to that trauma, we haven't been able to figure it out yet."

Staff have not ruled out injury by another bear.

"Definitely we haven't been able to rule that out," said Berkvens. "But we haven't seen anything on the cameras that indicates that it was another bear.

The bears do wrestle and play pretty rough and there's not a whole lot we can do to change that.They're playful critters.- Dr.CharleneBerkvens, associate zoo veterinarian

"The bears do wrestle and play pretty rough and there's not a whole lot we can do to change that. They're playful critters."

Without knowing what caused Eli's injury, it's hard to prevent it from happening again.

"The keepers look over the enclosure every day as a routine thinganyways,and we haven't been able to find any spot that likely would have led to it. We have looked into some of the large rocks in the enclosure, thinking maybe he slipped and fell and just hit his chin, but so far on the video we haven't been able to see any evidence of that."

Despite the lack of answers, staff haven't given up on finding a cause and are reviewing the footage from different angles, Berkvens said.

Zoo staff are upset about hisdeath, she added.

"I think it's even more difficult for them when we haven't been able to figure out what exactly caused it."

Eli was 318 kilos and 2 years old when he died. He arrived at the zoo in fall 2015.

This is not the first unexpected death at the zoo in recent years.

In 2014, a zookeeper accidently left a gate open between two tiger enclosures. Amur tiger Baikal, 19,died after a fight between him and younger tigerVasili.

Later that year, a blind harbour seal got stuck in one of the drains in the Journey to Churchill exhibitand drowned.

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