Can pets sense illness?

A cat has apparently "predicted" the deaths of 25 residents in a nursing home in the US. It seems fanciful but can pets detect illness or even death? The residents of Steere House Nursing and Rehabilitation Centre in Rhode Island would be forgiven for getting a little anxious if Oscar was to curl up next to them.

Not generally friendly to patients, this show of affection has been used to warn families that their loved one has not long to go. Sounds far-fetched? Animal behaviour experts in the US say Oscar is probably smelling a chemical given off by the body.

And Jacqueline Pritchard, an expert in animal behaviour in the UK, agrees the explanation is biochemical, rather than psychic."I don't doubt that the cat in this case is sensing death approaching. There's little we really know about it but as the body is shutting down, I would hypothesise that the cat is sensing and smelling the organs shutting down."

But there could also be a more simple explanation for Oscar's "ability", she says."We change our behaviour when we know someone is dying, so animals will pick that up." Dogs with an acute sense of smell and awareness are known to detect cancer and predict epileptic seizures.

A ground-breaking study by Dr. John Church, published in 2004, claimed to prove in principle that dogs could detect bladder cancer in urine. Since then a pilot study at a charity in Buckinghamshire has continued the research. There is also anecdotal evidence of dogs scenting a wide range of cancers such as lung, breast and skin, ahead of conventional diagnosis.

A woman in Wiltshire said her Chihuahua detected her breast cancer on three occasions, while a Dalmatian kept smelling a freckle that the owner discovered was a malignant tumour. The work of dogs in epilepsy is more advanced. The charity Support Dogs has provided 45 seizure alert dogs to epileptics such as Tony Brown-Griffin, 35, from Kent.

Twelve years ago, prior to her getting her first alert dog, she was suffering 12 major seizures a week and countless minor ones, so was housebound and childless. Now she is independent and a mother of two. Ajay, a golden retriever, licks her left hand 40 minutes before a major seizure, which only happens twice a week now, so she can get herself out of harm's way.

Despite the persuasive evidence of dogs' prowess in these areas, the case of Oscar the cat is still a bit of a mystery, says animal psychologist Roger Mugford. Although they can detect illness, he has never known of pets picking up on impending death, and cats would be unlikely candidates to behave like this if they could.

"The question is what motivates a cat to engage in this behaviour. Dogs being trained to detect cancer are trained with a pay-off of play if they do the right thing and if it's your own dog they have a familiar affectionate relationship and will pick the site of the tumour. But a cat in a nursing home?

"Dogs are very good at picking up on emotional changes and when people are depressed and inactive they are very good at comforting people in these circumstances. Elephants show the same altruistic tendencies, but not cats, they are very much more selfish, solitary creatures." One theory about how dogs have evolved this capacity is that their wolf ancestors developed an ability to tell when one of the pack was sick.

But it is not just in health that the heightened senses of animals have proved to be more advanced than humans'. Scientists remarked at how few wild animals died in the Asian tsunami in 2004, because they were able to sense the disaster and move to higher ground.