Service dogs can offer vital assistance to those who suffer from epilepsy, helping to prevent injury and signal for help when a seizure episode occurs. Whether dogs can detect seizures before they happen is another, more complicated question; anecdotal reports suggests that they can, but the evidence is inconclusive, and it hasn’t been clear what signals might trigger dogs to anticipate an oncoming seziure. But as Megan Schmidt reports for Discover, a small and intriguing new study suggests that people with epilepsy emit a specific odor when they are having seizures—and dogs can be trained to detect it.
The study’s very good subjects were five service dogs from Medical Mutts in Indianapolis, trained to respond to the bodily odors of people with diabetes, anxiety and epilepsy. To test the dogs’ seizure-detecting abilities, researchers recruited five patients with different types of epilepsy to collect sweat samples at various intervals: either during or right after a seizure, after moderate exercise and at random points in the day during calm activity. Seven samples from each patient were then placed in opaque cans, which the dogs were given a chance to sniff. Each dog underwent nine trials in total: five of those trials were repeat tests with the odor of one patient, and the rest were conducted with samples from the four remaining patients. The dogs had not been exposed to the patients’ scents prior to the experiment.
The results, the study authors write in Scientific Reports “were very clear: all dogs discriminated the seizure odor.” Some of the pooches had a better track record than others—the dogs correctly identified the seizure samples between 67 and 100 percent of the time—but all of their performances were “well above” the margins of chance, according to the researchers.
It’s not entirely surprising that dogs have super-powered noses when it comes to detecting human ailments. Our best animal buddies have been used to sniff out diseases like cancer and diabetes “with some success,” the researchers note. The new study, however, not only shows that dogs can smell seizures, but also offers the first known proof that different types of seizures are associated with common scents; the patients, after all, did not all have the same kind of epilepsy.
Granted, the study was small and limited in scope. It suggests that dogs can smell seizures as they happen, but the verdict is still out on whether the animals can detect seizures that are about to happen. Further research is also needed to determine precisely what bodily chemicals the dogs are smelling in the sweat of epileptic patients. But “[a]s far as implications go, the results are very exciting,” Tim Edwards, a behavioral analyst and senior lecturer at New Zealand’s University of Waikato, who was not involved in the study, tells Scientific American’s Emily Willingham. Perhaps understanding how dogs detect seizures can help pave the way for artificial intelligence technology that is able to do the same.
Additionally, the study authors maintain that their findings dispel the “belief that epilepsy and seizure types were too individual-specific for a general cue to be found.” And this, the researchers say, offers “hope” that people with epilepsy can be warned of oncoming seizures by their furry, faithful friends.