Canny canines can sniff out stress in humans, new research shows

Queens University Belfast investigators confirm ability that could aid training service and therapy dogs

Whether dogs could really smell fear has long been the subject of debate, but now one thing is certain – they can sniff out stress.

Researchers at Queen’s University Belfast, with the aid of four dogs and 36 sometimes stressed-out subjects, have confirmed the canine ability.

“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 dogs and therapy dogs,” explained Clara Wilson, a PhD student at the university’s school of psychology.

Researchers collected samples of sweat and breath from study participants before and after they did a difficult maths problem. They self-reported their stress levels, and researchers only used samples where the person’s blood pressure and heart rate had increased.


The Belfast dogs – Treo, Fingal, Soot and Winnie – were taught how to search a scent line-up and alert researchers to the correct sample.

The stressed and relaxed samples were then introduced but at this stage the researchers did not know if there was an odour difference that dogs could detect.

“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,” said Ms Wilson.

“The research highlights that dogs do not need visual or audio cues to pick up on human stress.”

Helen Parks, owner of cocker spaniel Treo, commented on the ability of a dog to use its nose to “see” the world.

“We believe this study really developed Treo’s ability to sense a change in emotion at home. The study reinforced for us that dogs are highly sensitive and intuitive animals and there is immense value in using what they do best – sniffing!”

Mark Hilliard

Mark Hilliard

Mark Hilliard is a reporter with The Irish Times