Officials at the Calgary Zoo are trying to figure out what went wrong after a hippopotamus transported from Denver died over the weekend.

Hazina, a six-year-old hippo, was transported by truck to Calgary to be part of a breeding program.

She left Denver Thursday morning and was unable to stand when she arrived Friday afternoon, more than 17 hours later. She died Saturday afternoon.

CTV Calgary reported that on her arrival zookeepers discovered she had been lying on one side too long and developed a pressure myopathy.

"Initially we thought it was due to just being stressed or fearful, and we tried to coax her up into a standing position. But it soon became evident that she was unable to rise," said Calgary Zoo veterinarian Dr. Doug Whiteside.

Zoo veterinarians said the hippo's small blood vessels may have been damaged and could no longer provide oxygen to her muscles.

Whiteside said the crate was large enough for Hazina to move around in and that she had been trained for months to be comfortable in the crate.

Unfortunately, she appeared to have trouble standing back up after going into a lying position, he said.

"Anytime we lose an animal here at the zoo, it's a tragedy, and certainly more of a tragedy for the keepers at the Denver zoo," said "At the Denver zoo, she had been born at the zoo and the keepers had known her for the full six years of her life."

Hazina was living with her father and brother in Denver, and was moved to Calgary to be with their two hippos, Sparky and Foggy.

Whiteside said Hazina was moved by an experienced animal transport company and her death was a "rare incident."

"What we need to focus on is to dissect the situation and figure out what went wrong and how to prevent it from going wrong in the future," he said.

Officials at the Calgary Zoo and the zoo in Denver have said they will investigate the death.

Hazina was named after the Swahili word for "treasures" - an apparently popular name for a hippo.

A Hippo by the same name at the Vancouver Zoo starred in a 2005 television commercial for Telus Inc., during which a little girl sang: "I want a hippopotamus for Christmas. Only a hippopotamus will do."

In June 2006, Vancouver's Hazina was moved to a larger home after the Prevention of Cruelty to Animals alleged she was being kept alone in a small concrete pen with a pool so shallow she couldn't float.

A Vancouver zoo spokesman said Monday their hippo is doing well.