Research Finds: Dogs Can Detect the Stress in Humans

According to the research, humans produce different smells through breath and sweat when stressed, and dogs can tell this apart from the smell when relaxed – even if it is somebody they do not know.

Washington: According to a new study by Queen’s University Belfast students, dogs can detect the stress in humans from sweat and breath.

The research results have been published in PLOS ONE. The study was taken out by Clara Wilson (Ph.D. researcher) and Kerry Campbell (MSc student) in the School of Psychology. They were led by Catherine Reeve, with support on collecting the human physiological measures from Zachary Petzel.

The study involved four dogs from Belfast – Treo, Fingal, Soot, and Winnie – and 36 people.

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

The dogs were trained to search a scent line-up and alert researchers to the correct sample. The stress and relaxed samples were then presented, but at this stage, the researchers didn’t know if there was an odor difference that dogs could detect.

Each dog was given one person’s stressed and relaxed samples in every test session, taken only four minutes apart. As a result, all the dogs could correctly alert the researchers to each person’s stress sample.

Clara Wilson, a Ph.D. student in the School of Psychology at Queen’s, explains: “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, providing evidence that dogs can smell stress from breath and sweat alone, which could be useful when training service dogs 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.”

One of the super sniffer dogs in the study was Treo, a two-year-old Cocker Spaniel. His owner Helen Parks says: “As the owner of a dog that thrives on sniffing, we were delighted and curious to see Treo take part in the study. We couldn’t wait to hear the weekly results when we collected him. He was always so excited to see the researchers at Queen’s and could find his way to the laboratory.

“The study made us more aware of a dog’s ability to use their 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!