Blog # 109: ANOTHER STUDY SHOWS DOGS CAN SMELL WHEN SEIZURES ARE ABOUT TO BEGIN==MORE SAFETY

Researchers ¹ find dogs can somehow detect a telltale scent linked to epileptic seizures. Can they be trained to warn owners when seizures are imminent? If so, this can add to the patient’s independence, confidence and safety in avoiding injury. They could then seek aid more expeditiously, too.

Dogs are known to detect odors of some cancers, diabetes and malaria. For example, the composition of exhaled breath is different in patients with lung cancer, inflammatory lung or liver disease, kidney dysfunction or diabetes.²

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 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 odors emitted during calm activity, while exercising, and during an attack.

Three dogs identified the seizure scent 100 percent of the time, while two others sniffed out the right sample in two out of three challenges.

“The results went beyond our expectations by showing that there is indeed a general odor of an epileptic seizure,” the lead University of Rennes French researcher, Dr. Amelie Catala, said. “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 parts per billion. The most sophisticated current “electronic noses”, meant to pick up potentially harmful odors that humans can't smell, have a detection threshold of around 300 parts per billion.

Catala said that while dogs had been shown previously to be able to sniff out chronic diseases, this experiment showed they could potentially diagnose acute health episodes that last just a few minutes. This constitutes a first proof that, despite the variety of seizures and individual odors, seizures are associated with olfactory characteristics. These results open a large field of research on the odor signature of seizures. Further studies will aim to look at potential applications in terms of anticipation of seizures.

“The study of odors 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.

1. Catalia A, Grandgeorge M, Schaff J-, et.al. Dogs demonstrate the existence of an epileptic seizure odor in humans Scientific Reports volume 9, Article number: 4103 (2019)

2. Buszewski B., Kesy M., Ligor, T.  Human exhaled air analytics: biomarkers of diseases. Biomed. Chromatogr. BMC 21, 553–566 (2007).

 
Lance Fogan, M.D. is Clinical Professor of Neurology at the David Geffen School of Medicine at UCLA. “DINGS” is his first novel. It is a mother’s dramatic story that teaches epilepsy, now available in eBook, audiobook and soft cover editions.