PROVIDENCE - In the two years since Oscar was adopted into the dementia unit of the Steere House Nursing and Rehabilitation Centre in Providence he has maintained close vigil over the deaths of more than 25 patients, nursing staff and doctors say.

Like any feline, Oscar gives a hefty portion of his day to sleep. He likes to doze on stacks of patient reports. Or on the desk at the nurses' station. Or in the linen closet.

When awake, however, the mixed-breed cat shows a solemn dedication to duty, making regular "inspection" rounds of the unit, sauntering in and out of patient rooms - as if checking on the condition of the occupants.

When death is near, Oscar nearly always appears at the last hour or so. Yet he shows no special interest in patients who are simply in poor shape, or even patients who may be dying but who still have a few days. Authorities in animal behavior have no explanation for Oscar's ability to sense imminent death. They theorize that he might detect some subtle change in metabolism - felines are as acutely sensitive to smells as dogs - but are stumped as to why he would show interest.

In any event, when Oscar settles on a patient's bed, caregivers take it as a sign that family members should be summoned immediately.

"We've come to recognize him hopping on the bed as one indicator the end is very near," said Mary, the charge nurse on the surprisingly cheery floor that is home to 41 patients in the final stages of Alzheimer's, Parkinson's, a stroke, and other mentally debilitating diseases. "Oscar's been consistently right."

Keeping pets has been a trend in nursing home care for several years. The Steere Centre, founded in 1874, has 120 residents, plus six cats, a slew of parakeets and a floppy-eared rabbit. Oscar's sole domain, however, is the locked dementia ward. He came to the unit as a kitten in July 2005, brought by a staff member to replace the floor's previous resident feline, Henry, who had died some months earlier.

A gregarious cat, quick to solicit ear scratches from a visitor, Oscar can be clownish at times. But it is Oscar's keen sense of impending death that has made him a legend.

"Medical people are skeptical at the start. But you wind up believing," One doctor commented. "Oscar is a normal cat with an extra-normal sense for death. He is drawn to death."

Occasionally, families are spooked by a cat keeping death watch, and Oscar is shooed from the bed and locked from the room. He does not like this. Other families are deeply appreciative of Oscar. One man lost his mother and his aunt at Steere; the octogenarian sisters both suffered from disease-induced dementia.

His mother died in November 2005; his aunt in March this year. In both cases, Oscar hopped onto the woman's bed near the final hour, cuddling close and purring.

"Oscar's presence gave a sense of completion and contentment," the man said. "Both women loved pets."

He added: "Oscar brought a special serenity to the room. What's more peaceful than a purring cat? What sound more beautiful to fill one's ears when leaving this life?"