Dogs can smell when humans are stressed, Queen’s study suggests

29 Sep 2022

Image: © grafoto1/

Four dogs were able to alert researchers to samples from stressed-out humans nearly 94pc of the time.

New research at Queen’s University Belfast (QUB) suggests that dogs can smell stress from a person’s sweat and breath.

This is based on the reactions of four dogs – Treo, Fingal, Soot and Winnie – who sniffed samples from 36 people.

Researchers collected samples of sweat and breath from the human participants before and after they did a tricky maths problem.

They self-reported their stress levels before and after the task, and researchers used samples where the person’s blood pressure and heart rate had increased to train the canine stress sniffers.

The dogs were taught how to search a scent line-up and alert researchers to the correct sample. Then, each dog was given a person’s relaxed and stressed samples, taken four minutes apart.

The Queen’s team said all the dogs were able to correctly alert the researchers to each person’s stress sample. The combined success rate of the four dogs was nearly 94pc across all the study’s sessions.

PhD student Clara Wilson said the results show we produce different smells through our sweat and breath that dogs can detect, even if they don’t know the person.

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

A woman sitting on a couch next to a dog, with a tan wall in the background.

Clara Wilson, a PhD student in the School of Psychology at Queen’s University Belfast. Image: QUB

Wilson said the results of the study could be useful when training service or therapy dogs.

Helen Parks is the owner of Treo, a two-year-old Cocker Spaniel who took part in the study. Parks said Treo “thrives on sniffing” and that she couldn’t wait to hear the results when he was collected from the study each week.

“He was always so excited to see the researchers at Queen’s and could find his own way to the laboratory,” Parks said. “The study made us more aware of a dog’s ability to use their nose to ‘see’ the world.”

Parks added that Treo seems to be able to sense a change in emotion within his home following the study.

“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,” she said.

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Leigh Mc Gowran is a journalist with Silicon Republic