According to a recent study by researchers at Queen’s University Belfast, dogs can detect stress through human sweat and breath.
The study involved four dogs from Belfast—Treo, Fingal, Soot, and Winnie—and 36 people.
Participants’ breath and sweat samples were taken by researchers both before and after they completed a challenging math problem. Before and after the task, they self-reported how stressed they were, and the researchers only used blood pressure and heart rate samples when the person had become more anxious.
The dogs were trained to find the right sample by searching through a line-up of scents. The samples from under stress and under relaxation were then combined, but at this point the researchers were unsure if the dogs could detect a difference in odor.
Each dog in every test received samples from one person who was both relaxed and under stress, taken just four minutes apart. Each dog was able to alert the researchers to the stress sample of each individual.
“The results 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 we are relaxed—even if it is someone they do not know,” explains Clara Wilson, a PhD student in the School of Psychology at Queen’s.
The study shows that canines can detect human stress without visual or aural cues. This is the first study of its kind, and it shows that canines can detect stress simply from breath and perspiration, which may be helpful when training service and therapy dogs.
“It also helps us learn more about how dogs may understand and react to the mental states of humans and sheds more light on the relationship between humans and dogs.”
Treo, a two-year-old Cocker Spaniel, was one of the super sniffer dogs that took part in the study. According to his owner, Helen Parks, “We were thrilled and curious to see Treo take part in the study. We couldn’t wait to hear the results each week when we collected him. He was always so excited to see the researchers at Queen’s and could find his own way to the laboratory.
The study increased our understanding of how a dog can “see” the world using its nose. We think that this study significantly enhanced Treo’s capacity to detect a shift in emotion at home. The study confirmed for us that dogs are extremely intuitive and sensitive creatures, and that using their best skill—sniffing—has enormous value.
Kerry Campbell, an MSc student in the School of Psychology, and Clara Wilson, a PhD researcher, did the study. It was led by Catherine Reeve, and Zachary Petzel helped them take measurements of people’s bodies. The results were published in PLOS ONE.
