One of the dogs in the study. Credit: Queen’s University Belfast.
Key Points:
- A new study shows dogs can smell stress from human sweat and breath, even in humans they do not know.
- All four trained dogs in the sample size were able to correctly alert the researchers to each person’s stress sample.
- The findings could be especially useful for training service and therapy dogs.
If you don’t want your dog to know you’re stressed, don’t sweat—or breathe. That’s according to a new study from researchers at Queen’s University Belfast that showed dogs can small stress from human sweat and breath.
Researchers collected samples of sweat and breath from 36 participants before and after they did a difficult math problem. The participants self-reported their stress levels before and after the task and researchers only used samples where the person’s blood pressure and heart rate had increased.
The four dogs—Treo, Fingal, Soot and Winnie—were taught how to search a scent line-up and alert researchers to the correct sample. The stress and relaxed samples were then introduced.
In every test session, each dog was given one person’s relaxed and stressed samples, taken only four minutes apart. All of the dogs were able to correctly alert the researchers to each person’s stress sample.
“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 Clara Wilson, a PhD student in the School of Psychology at Queen’s. “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 that dogs can smell stress from breath and sweat alone, which could be useful when training service dogs and therapy dogs.”
Although the sample size consists of only four dogs, it is in line with other bio-detection studies due to the time-consuming nature of training the dogs.
The researchers say it is possible that an odor component may be useful as a training aid for service dogs tasked with responding to acute stress responses in their owner.
More broadly, the study, published in PLOS One, sheds light on the human-dog relationship and adds to our understanding of how dogs may interpret, and interact with, human psychological states.
The researchers say further studies are required to establish what exact odor the dogs are detecting, the time-frame that this odor is detectable for, and potential interactions with chronic or long-term stress responses.
Information provided by Queen’s University Belfast.