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.

"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.

After about six months, the staff noticed the cat would make his own rounds, just like the doctors and nurses. He'd sniff and observe patients, and those he stayed with would wind up dying in a few hours.

Dosa said Oscar seems to take his work seriously and is generally aloof. "This is not a cat that's friendly to people," he said.