US scientist David Dosa was sceptical when first told that Oscar, an aloof cat kept by a nursing home, regularly predicted patients' deaths by snuggling alongside them in their final hours.

But Dr Dosa's doubts eroded after he and his colleagues tallied about 50 correct calls made by Oscar over five years, a process he explains in a book released this week, .

Oscar the nursing home cat ... knows when a patient is about to die. Credit:AP

The feline's bizarre talent astounds Dr Dosa, but he finds Oscar's real worth in his fierce insistence on being present when others turn away from life's most uncomfortable topic: death.

"People actually were taking great comfort in this idea, that this animal was there and might be there when their loved ones eventually pass," Dr Dosa said. "He was there when they couldn't be."