Polar bear's death an emotional hit to Winnipeg zoo staff

Staff at Winnipeg'sAssiniboine Park Zoo are trying to understand what led to the death of a young polar bear.

"They're taking it really it's tough for them," saidDr. ChrisEnright, thezoo's head of veterinary services, pausing tofind the right words.

"Eli was a young animal. Eli was a bear that has been with us for the past year and a half and really, had a second chance at life with our staff and the other bears here and with the public.

"It's hard on all of them when an animal passes away."

• 'A heartbreaking loss': Polar bear cub dead at Winnipeg zoo

The almost-three-year-old cub wasn't acting like itself on Friday, and didn't have much of an appetite, Enrightsaid. Eli was significantly worse on Saturday so adecision was madeto put him underanestheticto enable the vets to conduct acloser examination and collect some samples.

"Unfortunately, he experienced difficulty breathing and passed away,"Enrightsaid, adding thesamples will be sent away for further diagnostic testing.

Poring over video footage

The investigationinto the death is still in a preliminary stage, but doctors found significant swelling around hispharynx, at the back of his throat, and continuing down his neck along the trachea.

What caused that, however, is still unknown.

"At this point, we have a list of possibilities and further testing should help us whittleaway at that list to get to one final answer,"Enrightsaid.

"We're looking at the [video] footage, because we have numerous cameras on our polar bear exhibits. We're looking at an impact or trauma as a possibilty."

However, there are no indications of any external punctures to suggest an attack from another bear, and nointernal punctures that could have been made by jagged bones ingested by Eli, Enrightsaid.

When news of Eli's death came out on Sunday, ZoocheckCanada, a national animal protection charity, expressed concern there could be something toxic in the enclosure.

Enrightsaid that doesn't appear to be the issue.

"It's absolutely something that we look at closely whenever we have an unexpected incident of illness or mortality," he said. "We don't, at this point, think that there's anything that could spread to the other bears or other animals in the zoo."

Eli arrived at the zoo's polar bear conservation centre as aone-year-old cub with his brother, York, in October 2015.

• Polar bear cubs atAssiniboinePark Zoo named York and Eli
• Churchill polar bear cubs ready to meet public atAssiniboinePark Zoo
• Orphaned polar bear cubs from Churchill arrive atAssiniboinePark Zoo

They were orphaned when their mother was accidentally hit by a cracker shell someone used to scare her and the cubs away from a building entrance in Churchill.

Manitoba Conservation determined the cubs were too young to survive on their own and had them transferred tothe zoo's Leatherdale International Polar Bear Conservation Centre. After a quarantine period, they were eventually added to the zoo's 10-acreJourney to Churchill enclosure with the other polar bears.

"We have a great facility and great staff, and we really put that effort into looking after our bears the best way we know how. And I do think our bears here have a good quality of life," Enrightsaid, knowing there will be criticisms from people opposed to zoos.

According to an assessment byManitoba Conservation, Eli and Yorkwould likely have died ifthey remained in the wild, he said.

There are now eight polar bearsliving in theJourney to Churchill exhibit.