Can dogs really
smell a seizure coming?

The full narration of the video.

Two dogs, both living with someone who has epilepsy. One runs to press an alarm after its person collapses. The other starts pawing at its person's leg while they still seem perfectly fine. Minutes later, a seizure really comes. How did the dog know? And how do you train a dog to do that? First, epilepsy. The brain's electrical signals suddenly go haywire for a while, and a person may fall and shake, usually for a few minutes. About fifty million people worldwide have epilepsy.

The dogs that help them actually come in two kinds. The first kind helps during a seizure: staying close, pressing an alarm button, running to get family. This kind can be trained reliably. It's done just like teaching a dog to sit: pressing the button, fetching family, one move at a time. A treat for every success. Finally, those moves get linked to the moment the person goes down.

The second kind, warning ahead of time, is much harder. Owners say their dogs warn anywhere from seconds to hours early. But mostly that's owners' own records, and no one has checked them strictly. So what is the dog relying on? A superpower? Spotting something off in its person's face? Scientists are betting on something else: the nose. In 2019, researchers in France set out seven cans. Only one held sweat and breath from a patient during a seizure. Five trained dogs sniffed them one by one.

Three dogs got it right every time; the other two, two times out of three. During a seizure, the body really does give off a distinctive smell. Training works much like teaching a dog to find drugs: let it smell the scent, reward it when it picks correctly, over and over, until it raises the alarm the moment it smells it. But smelling a seizure while it happens isn't the same as smelling it coming.

In 2021, US researchers collected patients' sweat every hour and gave it to trained dogs to sniff. For about eight in ten seizures, the dogs picked up the scent before the seizure began. So early warning is most likely this: the dog's nose catches a change in the body before we can. But these studies are small, a few dogs and a few dozen patients. The evidence is still thin. Life with a dog really is different, too. A 2024 trial in the Netherlands found that after patients got a dog, their seizures dropped by about a third.

But a dog can't replace a doctor, or medicine. And one thing nobody can say for sure: could some dogs be doing more than smelling, spotting tiny changes in their person that we never notice? Which side are you on: the nose, or the eyes?