DOGS REALLY CAN TELL WHEN WE’RE STRESSED
Pet pooches can sniff out the scent of stress hormones in our sweat and breath
As any dog owner will tell you, their canine friend can tell when they are feeling stressed. Now, researchers at Queen’s University Belfast have demonstrated that they’re right: dogs do know when we’re stressed, because they can smell it.
The finding follows previous studies on the canine sense of smell, which have shown that dogs are able to sniff out cancer and COVID-19 in human sweat.
To make this latest discovery, the team recruited four dogs – Treo, Fingal, Soot and Winnie – from domestic homes in Belfast, along with 36 human volunteers. They set the humans a complicated maths problem designed to raise their stress levels and took samples of their sweat and breath before and after they attempted to solve it. The researchers monitored the volunteers throughout the experiment and only took the second sample when they detected increases in their blood pressure and heart rate – both clear indicators of stress.
Meanwhile, the dogs were trained to pick out specific scents from a line-up.
The team then presented each of the dogs with a selection of scents, including a volunteer’s relaxed and stressed samples, to see if the dogs could distinguish between them. All four of the dogs were able to correctly identify each volunteer’s stressed sample, even though they had never met them before.
“The findings show that humans produce different smells through our sweat and breath when we’re stressed and dogs can tell these apart from our smell when relaxed – even if it’s someone they don’t know,” said researcher Clara Wilson, a PhD student in the school of psychology at Queen’s University.
“The research highlights that dogs don’t need visual or audio cues to pick up on human stress. This is the first study of its kind and it provides evidence that dogs can smell stress from breath and sweat alone, which could be useful when training service and therapy dogs.
“It also helps to shed more light on the human-dog relationship and adds to our understanding of how dogs may interpret and interact with human psychological states.”
SCENTS AND SENSE-ABILITY
Dogs are famous for their incredible sense of smell. Here are just a few of the factors that make their noses so sensitive…
SMELLING IN STEREO
Each of a dog’s nostrils is able to smell independently. This allows them to determine which direction a particular scent is coming from.
A NUMBERS GAME
Our canine companions have around 220 million scent receptors in their noses. Humans have just five million.
SENSITIVE TO SCENTS
With so many more receptors in their noses, a dog’s sense of smell is around 10,000 times more sensitive than a human’s.
ON THE PODCAST
Listen to an episode of the Instant Genius podcast about medical detection dogs at bit.ly/detection_dogs