We know that our four-legged friends understand their surroundings through their sense of smell. Dogs have about 220 million cells specially designed to detect smells, which humans use in many areas, such as detecting drugs and explosives and identifying certain medical conditions such as cancer and even COVID-19. 19. But what about stress? A research group from the Queen’s University of Belfast in the UK claims a study published in the scientific journal ” PLOS ONE that dogs can “smell” it in humans. And this is for the simple reason that our body gives off a particular smell when we are stressed, a condition that dogs can then identify from our sweat but also from our breathing. To come to this conclusion, the researchers recruited four dogs, named Treo, Fingal, Soot and Winnie, and 36 people. They agreed to provide sweat and breath samples before and after solving a difficult math problem.
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Each participant also had to “self-report” their level of stress felt before and after this resolution task, the researchers used only samples where blood pressure and rate of man’s heart rose. For their part, the dogs learned to identify the container with the correct breath and sweat sample, even if the choice included unused gauze, samples from another person, or samples from the same person. taken elsewhere. With the team confident that the dogs understood the procedure, they then introduced the breath and sweat samples taken from the 36 participants. The dogs were instructed to choose samples taken after the math exercise from three containers, the other two containing unused gauze. The researchers then tested whether the dogs could do the same if the option included not only unused gauze, but samples taken from the same participant before the task, when they were more relaxed. Each set of samples was shown to one dog in 20 trials.
Dogs successfully ‘smell’ the scent of stress
The results revealed that in 675 out of 720 tests (94%), the dogs successfully identified a sweat or breath sample taken from a stressed participant. ” The results show that we as humans produce different scents through our sweat and breath when we are stressed and that dogs can recognize it from our scent when we are relaxed, even if it is a person we are feeling. . ‘they don’t know each other. said Clara Wilson, who directed the study. He added: “ Research shows that dogs don’t need visual or audio cues to pick up human stress. This is the first study of its kind and provides evidence that dogs can detect stress through breath and sweat alone. “. These results are important because they not only prove conclusively that humans, when reacting to stress, change their olfactory profile but also that they have their usefulness in terms of training service dogs, such as those who support people with post-traumatic stress disorder (PTSD).
And although this study was carried out with dogs that were well trained to communicate with the samples to which they were exposed, the scientific team hypothesized that even companion dogs would know when their master entered a situation of tension. ” Our findings increase our understanding of how they interpret and interact with human psychological states. “, ending this one. Interviewed in the newspaper The Guardian on this topic, Claire Guest, co-founder of the charity Medical Detection Dogs; said he was not surprised by the results, as medical assistance dogs are trained to alert people with complex medical conditions when they are at risk of a life-threatening medical event by detecting changes in their smell. Indeed, ” some of these conditions are believed to be caused by a change in hormone levels, so we are not surprised to know that dogs can detect stress in people because it can also be linked to hormonal fluctuations. »