BOSTON -- An elephant who died "in the prime of her life" at a Massachusetts zoo this week has raised a red flag for an animal activist group.

In Defense of Animals filed a complaint Friday with the U.S. Department of Agriculture, regarding Dondi the elephant's death on Wednesday at the Southwick Zoo in Mendon.

“Dondi’s unexpected death raises a red flag because at age 36 she should have been in the prime of life,” said Catherine Doyle, the IDA Elephant Campaign director.

Asian elephants like Dondi normally live to be between 60 and 70 years old.

IDA also sent another letter to Justine Brewer, the president of Southwick Zoo. In that letter, IDA requested that the zoo release Dondi's veterinary records and necropsy reports, on the grounds that the public has the right to know what caused the fatality.

Doctors were unable to identify the illness prior to her death.

During her time at the Southwick Zoo, Dondi came into direct contact with humans on a regular basis when she gave rides. In the winter, she gave rides in Florida, where she also performed circus tricks, according to IDA.

The health issue is significant because elephants can carry diseases that can be transmitted to people and are difficult to detect, such as tuberculosis.

IDA hoped that the release of those veterinary records would calm whatever public health concerns may arise.

They also asked that the zoo not replace Dondi with another elephant, on the grounds that the elephant exhibit was too small to fully support a healthy animal.

“Though the zoo may have been well-intentioned, Dondi led a sad and unnatural life for an elephant,” said Doyle. “She was trucked across the country, confined in cramped pens, forced to perform circus tricks and give rides, and lived without the companionship of another elephant.”

Studies have shown that elephants who spend much of their lives in zoos die much earlier than their brethren in a relatively protected wild population. Close confinement in zoos will often lead to severe physical and psychological problems for the animals.

Phil and Francine Schacht originally rescued Dondi from a Thai lumber camp in 1975. Dondi would go on to accompany the family on tours to promote environmental awareness.