EDMONTON — Animal rights groups are threatening a lawsuit unless the City of Edmonton agrees by next month to move Lucy the elephant from the Valley Zoo to a sanctuary in the United States.

Zoocheck Canada and People for the Ethical Treatment of Animals have written a letter outlining their demands to Mayor Stephen Mandel and city councillors.

They have obtained a legal opinion written by prominent Toronto-based lawyer Clayton Ruby, who said in a telephone interview Tuesday that he plans to argue that the city is violating Alberta's Animal Protection Act by keeping an animal in distress.

The legislation specifies that an animal is in distress if it's injured, sick or suffering, or subjected to undue hardship or privation.

Ruby said he will file a lawsuit in Alberta Court of Queen's Bench unless the City of Edmonton agrees by Nov. 19 to allow Lucy to be shipped to a sanctuary in California. He noted a court case could cost city taxpayers dearly.

"She's given enough to the children and families of Edmonton. It's time to let her go retire in California, rather than spend hundreds of thousands of dollars fighting this lawsuit," he said.

In his legal brief, Ruby writes that the 34-year-old elephant lacks the "necessities of and comforts of life" because she is kept alone, despite acknowledgment by experts that female elephants are highly social animals and should be housed with others of their kind. He notes that provincial standards for zoos in Alberta require that "animals must be maintained in numbers sufficient to meet their behavioural and social needs."

He also alleges that Lucy is bored, obese from lack of exercise, has undiagnosed upper respiratory problems and suffers from chronic foot infections -- something Ruby said is one of the leading causes of premature death in captive elephants.

Linda Cochrane, general manager of the city's Community Services Department, which oversees operations at the zoo, said she wasn't surprised at this latest development because a popular television celebrity told them about a possible escalation in tactics when he visited Edmonton last month.

Bob Barker, who was host of the TV game show "The Price is Right" for decades in the United States, held a meeting with city and zoo officials last month where he pleaded for the elephant's removal to a more enriching facility where she could be housed in a herd and roam freely.

"We're becoming used to the tenacity of some of the people connected with this situation," said Cochrane. "That's why I think it's so important that we act with integrity and professionalism relative to doing what's in Lucy's best interest."

The possible lawsuit has been referred to the city's legal department for some advice, she said.

Before Barker's visit, the zoo issued a report by a veterinary expert in San Diego that said the pachyderm is fine where she is and a long journey could be life-threatening.

Cochrane maintained Lucy isn't in distress and that she is well-cared for and happy in the zoo where she's been living for more than 30 years. She said zoo officials are developing a plan to deal with Lucy's inflamed sinuses, which cause her breathing difficulties. Cochrane insisted there's nothing wrong with the elephant's feet aside from some arthritis.

The controversy over Lucy's fate has garnered media attention across North America and pleas not only from Barker, but also from Canadian-born actor, William Shatner, and several prominent authors.

"I'm not so sure that I understood it would go to this extent, when all we've ever wanted to do is to take care of our elephant to the best of our ability and to take care of (Lucy's) best interests," Cochrane said.

Ruby dismissed the argument that moving the pachyderm could cause the animal's death. He said it's not acceptable for the zoo to use illnesses it caused as a justification for failing to "alleviate that suffering."

The animal rights groups have offered to pay the tab to transport the elephant to a sanctuary. That bill could range anywhere from $20,000 to more than $70,000, Ruby said.