By Julie Steenhuysen

CHICAGO (Reuters) - When Oscar the Cat visits residents of the Steere House Nursing and Rehabilitation Center in Providence, Rhode Island, the staff jumps into action -- Oscar can sense within hours when someone is about to die.

In his two years living in Steere's end-stage dementia unit, Oscar has been at the bedside of more than 25 residents shortly before they died, according to Dr. David Dosa of Brown University in Providence.

He wrote about Oscar in the New England Journal of Medicine.

"It's not that the cat is consistently there first," Dr. Joan Teno, a professor of community health at Brown University, who sees patients in the unit. "But the cat always does manage to make an appearance, and it always seems to be in the last two hours."

"I don't think this is a psychic cat," said Teno. "I think there's probably a biochemical explanation," she said in a telephone interview.

"That is such a cat thing to do," said Thomas Graves, a feline expert and chief of small animal medicine at the University of Illinois College of Veterinary Medicine.

Graves said there is no evidence to suggest cats can sense death, but he doesn't discount it for a minute.

"Those things are hard to study. I think probably dogs and cats can sense things we can't," he said.

On a particular day detailed by Dr. Dosa, Oscar settled onto the bed of a patient in room 313.

His presence sent staff off to make calls and set up vigil.

When a grandson asked why the cat was there, his mother explained: "He is here to help Grandma get to heaven," according to Dosa's account.

She died a half an hour later.