Blizzard, a five-year-old polar bear that has lived at the Assiniboine Park Zoo since it arrived as an orphan cub in 2014, has died.

It's the second polar bear death in as many years at the zoo.

"Blizzard was a beautiful bear and he will be dearly missed by zoo staff visitors and volunteers. It is unusual to lose a bear this young," said the zoo's director of veterinary services, Chris Enright.

Blizzard lost his appetite and started acting lethargic 13 days ago.

"Our veterinary team made the decision to anesthetize Blizzard in order to conduct a full assessment of his condition," Enright said.

Blizzard was treated with antibiotics and appeared to be doing quite well until his behaviour changed and his condition worsened this weekend.

"Monday morning the decision was made to anesthetize him again in order to reassess his condition and take appropriate measures. Again the procedure went well but in the course of reversing the anesthesia and recovering Blizzard experienced respiratory distress. Veterinary and animal care staff did absolutely everything we could to save him but sadly he passed away," Enright said.

Preliminary results from a necropsy, which is an animal autopsy, indicate signs of inflammation, fluid in the chest cavity and some abnormalities in his heart.

"It is always sad when we lose a one of our beloved animals at the zoo, but a loss under these circumstances is particularly challenging," Enright said.

This polar bear, named Eli, was 2½ years old it died at the zoo in July 2017. (Submitted by Assiniboine Park Zoo) A polar bear named Eli died at the zoo in July 2017. An autopsy showed neck tissue that was swollen enough to block its airways and make it difficult for the 2½-year-old bear to breathe.

Staff did not know what caused the injury but suspected it could have happened when Eli was playing with some of the other bears.

A zoo spokesperson said at the time that the bears like to play and, considering their size and weight, can be pretty rough with one another.

According to their biography on the zoo's website, Blizzard and his sister Star were orphaned cubs spotted by a helicopter pilot near the Hudson Bay coastline when they were approximately a year old.

Their mother was never found. The two were brought to the zoo because their chance of survival on their own was considered slim.

"I remember the first checkup of Blizzard and I remember bringing him down and he was just one of those bears that was relaxed from the get-go," Enright said.

Staff at the zoo, can work their entire careers with a particular animal and can get very attached to them.

"They really certainly feel the loss of any of the animals in the zoo just as we might with the dog or a cat at home," Enright said.