Dr David Dosa, a geriatrician and assistant professor at Brown University, said that five years of records showed Oscar rarely erring, sometimes proving medical staff at the New England nursing home wrong in their predictions over which patients were close to death.
The cat, now five and generally unsociable, was adopted as a kitten at the Steere House Nursing and Rehabilitation Centre in Providence, Rhode Island, which specialises in caring for people with severe dementia.
The tortoiseshell and white cat spends its days pacing from room to room, rarely spending any time with patients except those with just hours to live.
If kept outside the room of a dying patient, Oscar will scratch on the door trying to get in.
When nurses once placed the cat on the bed of a patient they thought close to death, Oscar "charged out" and went to sit beside someone in another room. The cat's judgement was better than that of the nurses: the second patient died that evening, while the first lived for two more days.