Dogs can predict epileptic seizures, offering a warning sign to owners that has the potential to save lives, new research has found.
Epileptic seizures are associated with a specific smell which is detectable by pet dogs.
Scientists at Queen's University Belfast analysed the reaction of dogs to odours and found they could predict when a seizure was imminent.
A reliable early warning system to make people with epilepsy aware of an impending seizure has the potential to save lives, reduce injury, provide an opportunity for medical intervention and return a sense of independence to those living with unpredictable seizures.
Epilepsy is a debilitating and potentially life-threatening neurological condition which affects approximately 65 million people worldwide, of whom 30% are unable to control their seizures by medication.
There is currently no reliable and simple early warning seizure-onset device available, which means many people with unstable epilepsy live in fear of injury or sudden death and the negative impact of social stigmatisation.
There have been anecdotal accounts of pet dogs predicting their owner's epileptic seizures by becoming attentive and demonstrating attention-seeking behaviours, but to date no scientific study has investigated the veracity of these claims.
Lead researcher Dr Neil Powell, from the School of Biological Sciences at Queen's, said: "We hypothesised that, given the extraordinary sense of smell of dogs, a volatile organic compound exhaled by the dog's epileptic owner may provide an early warning trigger mechanism to which make dogs react before the seizure.
"The results have shown pet dogs to be a reliable source to detect an onset seizure."
The study has been published in the journal MDPI Animals.
The researchers explored how a cohort of pet dogs reacted to the emergence of seizure-associated odours.
Using two specially designed pieces of apparatus called the Remote Odour Delivery Mechanism, the researchers separately delivered epileptic seizure-associated odours and non-seizure associated odours and recorded the reactions of the dogs to each.
Using 19 pet dogs with no experience of epilepsy, the researchers exposed them to odours that were deemed to be characteristic of three seizure phases, by using sweat harvested from people with epilepsy.
By altering the alternating odours emerging from sweat samples, captured before seizure, during a seizure and after a seizure, and two non-seizure controls, the researchers recorded the response of the pets.
They found that all 19 dogs demonstrated more affiliative behavioural changes when confronted by seizure-associated odours, compared with their response to control odours.
Dr Powell added: "Our findings clearly showed that all dogs reacted to the seizure-associated odour, whether this was through making eye contact with their owner, touching them, crying or barking.
"There is a unique volatile smell linked to epileptic seizures, detectable by dogs who can in turn warn their owner a seizure is likely to occur.
"Our research was based on pet dogs with no prior training. If we can train dogs, this has the potential to make a big difference to owners who experience unpredictable seizures and should go a long way in improving not only their safety, but also their quality of life."
The research was funded by and conducted in partnership with Epilepsy Ireland and Disability Assistance Dogs.
Peter Murphy, chief executive of Epilepsy Ireland, said: "A reliable method of seizure prediction and detection is the holy grail for many people living with epilepsy as well as the parents of children with the condition.
"This is especially the case where seizures involve the loss of consciousness, with a high risk of injury.
"While recent efforts have focused on technological solutions, it is exciting and very welcome news that anecdotal reports of dogs' ability to predict seizures have now been backed up by scientific evidence."