Previous tests have shown that dogs are able to detect the odours of certain diseases, including some cancers, diabetes and malaria.

There is also anecdotal evidence they can sense that their owner may be about to have a seizure, though this was poorly understood until now.

Researchers in France used five dogs – Casey, Dodger, Lana, Zoey and Roo – in a study to sniff out a scent specifically linked to a human seizure.

They presented the dogs with a variety of smells taken from epileptic patients, including body odours emitted during calm activity, while exercising, and during an attack.

Casey, Dodger and Zoey all identified the seizure scent 100% of the time, while Lana and Roo sniffed out the right sample two goes out of three.

“The results went beyond our expectations by showing that there is indeed a general odour of an epileptic seizure,” said Amelie Catala, a researcher at the University of Rennes and lead study author.

“We hope it will open new lines of research that could help anticipate seizures, and thus, get patients to seek security.”

Dogs’ noses have evolved to be highly sensitive and can detect specific organic compounds at a concentration of less than 0.001 part per billion.

The most sophisticated current “electronic noses”, meant to pick up potentially harmful odours that humans can’t smell, have a detection threshold of around 300 parts per billion.

Catala said that while dogs have previously been shown to be able to sniff out chronic diseases, this experiment showed they could potentially diagnose acute health episodes that last just a few minutes.

“The study of odours by the use of dogs constitutes a fast, low-cost, non-invasive and effective screening method of diseases that can be difficult to identify normally,” she said.

The paper was published in the journal Nature Scientific Reports. – AFP Relaxnews