Can well-trained service dogs sense an impending seizure in their epileptic masters?
Probably not, neurologists said in this week's issue of the journal Neurology. But even if dogs can't read our brainwaves per se, they still possess an almost uncanny ability to sense danger and protect their owners.
Seizure-alert dogs can sense and notify their human companions of an oncoming seizure. The notifying behavior would be anything markedly different from the dog's usual behavior, including close eye contact, circling, pawing or barking. This alerting behavior has been reported to show up anywhere from several seconds to 45 minutes or more before the onset of the seizure.
But a recent study suggests that the dogs don't sense the actual surge in electrical brain activity that usually characterizes a seizure -- so what do these dogs really pick up on?
Some epileptic owners of seizure-alerting dogs (SADs) have normal brain wave activity during convulsive events, according to the new report. This means the dog owner has "psychogenic non-epileptic seizures" (PNES) -- which is different from true epilepsy.
The same report recalled another seizure-alert dog that supposedly didn't so much predict his owner's seizures as cause them by licking the owner's face. Strange, but possibly true.
So, the seizure-sensing dogs that these researchers looked at weren't reacting to abnormal brain waves. Perhaps they detected a sound or odor to alert them to the impending danger.
It's not too much of a stretch of the imagination to believe that dogs, with their extraordinary sensory abilities, might be able to sense various impending events more quickly and more accurately than humans who are, by comparison, relatively insensitive.
Veterinarians often hear that dogs who are afraid of thunderstorms begin to pace and whine well before owners have the faintest notion that a storm is brewing. Dogs are also reported to be able to sense impending earthquakes, their owners' imminent return and their owners' emotional state.
What is it about dogs that make some of them supersensitive superheros?
Think of the weapons they have. Their sense of smell is second to none and is beyond our comprehension. They can hear in the ultrasound range, and they are masters of observation and interpretation when it comes to body language. Dogs can practically see you sweat.
I've seen dogs trained to warn diabetic owners of an impending diabetic seizure -- the dogs can actually sense their owners' low blood sugar. A diabetic client of mine had a German shepherd. The dog didn't really like her husband, and the animal only ever approached him once -- when my client was asleep and about to have a low blood-sugar crisis.
I also know a formerly seizure-prone dog trainer whose Keeshond warns her of impending epileptic events with such reliability that she no longer needs medication.
(Of course, don't try that at home.)
A diabetic's metabolism changes before a seizure induced by low blood sugar. This change subtly smells like ketosis, which is like nail polish remover.
It stands to reason that the smell wouldn't be too difficult for a dog to detect. The dog learns that when he smells that smell, all hell breaks lose not long afterwards, so he learns to act pre-emptively.
Accordingly, he barks in alarm or licks his owner submissively when the odor occurs. Once owners appreciate that their dog displays this behavior before they have a seizure, it's case closed.
Scientific studies may suggest that seizure-sensing dogs don't respond to real epilepsy, but that kind of research is very complicated to carry out and may not reflect what happens in the real world. So while the researchers may be going back to the drawing board, some seizure-prone individuals will continue to use and swear by service dogs.
Nicholas Dodman is director of the Animal Behavior Clinic at the Tufts Cummings School of Veterinary Medicine in Massachusetts. Check him out at ThePetDocs.Com