Dogs can sometimes predict an epileptic owner's seizure or sniff at an owner's mole, signaling a possible cancer.
Now, it appears a cat can predict the deaths of patients in a nursing home.
When Oscar curls up on a patient's bed and stays there, the staff knows it's time to call the family. It usually means the patient has less than four hours to live.
Click here to see photos of the cat
The feline's accuracy has been observed in 25 cases at Steere House Nursing and Rehabilitation Center.
"He doesn't make too many mistakes. He seems to understand when patients are about to die," Dr. David Dosa said in an interview. He describes the phenomenon in a poignant essay in Thursday's issue of the New England Journal of Medicine.
"Many family members take some solace from it. They appreciate the companionship that the cat provides for their dying loved one," said Dosa, a geriatrician and assistant professor of medicine at Brown University.
The 2-year-old Oscar was adopted as a kitten and grew up in a third-floor dementia unit at Steere House, which treats people with Alzheimer's, Parkinson's disease and other illnesses.
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.
Oscar is better at predicting death than the people who work there, said Dr. Joan Teno of Brown University, who treats patients at the nursing home and is an expert on care for the terminally ill.
She was convinced of Oscar's talent when he made his 13th correct call. While observing one patient, Teno said she noticed the woman wasn't eating, was breathing with difficulty and that her legs had a bluish tinge, signs that often mean death is near.
Oscar wouldn't stay inside the room though, so Teno thought his streak was broken. Instead, it turned out the doctor's prediction was roughly 10 hours too early. Sure enough, during the patient's final two hours, nurses told Teno that Oscar joined the woman at her bedside.
Doctors say most of the people who get a visit from the sweet-faced, gray-and-white cat are so ill they probably don't know he's there, so patients aren't aware he's a harbinger of death. Most families are grateful for the advanced warning, although one wanted Oscar out of the room while a family member died. When Oscar is put outside, he paces and meows his displeasure.
No one's certain if Oscar's behavior is scientifically significant or points to a cause. Teno wonders if the cat notices telltale scents or reads something into the behavior of the nurses who raised him.
Nicholas Dodman, who directs an animal behavioral clinic at the Cummings School of Veterinary Medicine at Tufts University and has read Dosa's article, said the only way to know is to carefully document how Oscar divides his time between the living and dying.
If Oscar really is a furry grim reaper, it's also possible his behavior could be driven by self-centered pleasures like a heated blanket placed on a dying person, Dodman said.
Nursing home staffers aren't concerned with explaining Oscar, so long as he gives families a better chance of saying goodbye to the dying.
Oscar recently received a wall plaque commending his "compassionate hospice care."