Dogs able to detect stressed humans from their sweat

DOGS can smell when you are stressed because of chemicals in sweat, scientists have discovered.

The unique relationship between dogs – which have an extraordinarily sensitive sense of smell – and people means the animals are especially attuned to our odours.

They are already used to identify when people are at risk of diabetic flareups, seizures and anxiety attacks.

And now it has been established that dogs can also sense when people are feeling under pressure. Scientists from Queen’s University Belfast found canines to be more than 90 per cent effective at identifying stressed people.

Four dogs from Belfast – Treo, Fingal, Soot and Winnie – smelled sweat samples of 36 people before and after they were subjected to a rapid arithmetic quiz designed to increase stress levels.

The dogs had been trained to bark when they found a smell that matched a “stressed” sample they were given beforehand. They were successful at finding a match 675 times out of 720, or 93.75 per cent of the time, data published in the journal Plos One show.

“Given dogs’ established ability to discriminate between other physiological processes of the human body, it is conceivable that dogs can detect volatile organic compound changes associated with acute physiological stress,” the researchers wrote in their study.

Study author Clara Wilson, a PHD student in the school of psychology, said: “The findings show that we, as humans, produce different smells through our sweat and breath when we are stressed and dogs can tell this apart from our smell when relaxed, even if it is someone they do not know.

“The research highlights that dogs do not need visual or audio cues to pick up on human stress. This is the first study of its kind and it provides evidence 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.”

The journal also published data from a trial from the University of Liverpool where scientists made a virtual-reality world around a computer-generated golden labrador. Users put on a VR headset to interact with the dog, which has calm and aggressive settings.

The researchers say the technology could be used to help people cope with an aggressive dog, but could also benefit people with a phobia of the animals.