28 June 2004

From NewScientist.com

Dogs can predict epileptic seizures

Some dogs can predict when a child will have an epileptic seizure, a new study has revealed. These dogs not only protect their charges from injuries, such as falling, but also seem to help kids deal with the daily struggle of epilepsy.

Nine of the 60 dogs in the study (15 per cent) were able to predict a seizure by licking, whimpering, or standing next to the child. These dogs were remarkably accurate—they predicted 80 per cent of seizures, with no false reports.

However, those interested in owning a dog with these skills cannot yet just order one. The dogs were not trained, but instead began predicting seizures spontaneously within a month of moving in with their owners.

"No one is reliably training such dogs yet," says Adam Kirton, a neurologist at Alberta Children's Hospital in Canada and lead author of the study. His group is looking into setting up a training program. However, some epilepsy patients do already have dogs that have been trained to protect them during a seizure.

Children with epilepsy are at risk of falling or choking during a seizure. The injury rate is highly variable, but can be about 20 per cent for some types of childhood epilepsy.

"But the worst part of the disease isn't a seizure, it's fear of the next seizure," says Kirton. "By knowing when a seizure might happen, it could liberate them and free them to do what they want to do."

Minutes to hours

Before the new study, reports of dogs predicting seizures had only been anecdotal. So Kirton and colleagues attempted to systematically assess dog behaviour by sending questionnaires to families in their clinic.

Forty-two percent of the families with both an epileptic child and a dog said their dogs responded to seizures. And nine of these dogs actually anticipated the seizure, alerting families minutes to hours before the seizure occurred. Also, dog-owning families reported a higher quality of life than those without, with the owners of seizure-alerting dogs reporting the highest values.

One possible weakness of the study is that the behaviour was reported by the dog-owners themselves, who may overestimated their dog's abilities. Kirton therefore plans to do another study in a more clinical setting, which will also try to determine how these dogs predict seizures.

At present, the mechanism is unknown. But some researchers speculate that the dog could be using subtle visual or olfactory cues that occur before a seizure.

Gregory Holmes, a neurologist at Dartmouth Medical School in New Hampshire, says the dogs could be detecting a change in smell. "People have autonomic changes, such as increased sweating, which a dog could pick up on."

According to Douglas Nordli, director of the children's epilepsy center at Children's Memorial Hospital in Chicago, such external changes could result from a small electrical discharge that occurs in the brain before the full blown electrical seizure.

Journal reference: Neurology (vol 62, p 2303)

Emily Singer

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