Dogs can sense when we’re stressed, study finds

A research dog sniffing a person’s breath and sweat sample. Credit: Kerry Campbell, CC-BY 4.0 (

Physiological processes associated with an acute psychological stress response produce changes in human breath and sweat that dogs can detect with 93.75% accuracy, according to a new study published this week in the open-access journal. PLOS ONE by Clara Wilson of Queen’s University Belfast, UK, and colleagues.

Odors emitted by the body are chemical signals that have evolved for communication, primarily within species. Given dogs’ remarkable sense of smell, their history of close domestication with humans, and their use to support human psychological conditions such as anxiety, panic attacks, and post-traumatic stress disorder (PTSD) , the researchers wondered if dogs could detect chemical signals to react. to the psychological states of their owners.

In the new study, the researchers collected breath and sweat samples from non-smokers who had not eaten or drunk recently. Samples were taken before and after a quick arithmetic task, along with self-reported stress levels and objective physiological measures: heart rate (HR) and blood pressure (BP).

Samples from 36 participants who reported increased stress from the task and experienced increased heart rate and blood pressure during the task were presented to trained dogs within three hours of collection. Four dogs of different breeds and breed mixes had been trained, using a clicker as well as kibble, to match scents in a discrimination task. In testing, dogs were asked to find the participant’s stress sample (taken at the end of the task) while the same person’s relaxed sample (taken just minutes before, before the task started ) was also in the sample list.

Overall, the dogs were able to detect and perform their alert behavior on the sample taken during stress in 675 of 720 trials, or 93.75% of the time, significantly more than expected by chance (p

The authors conclude that dogs can detect an odor associated with the change in volatile organic compounds produced by humans in response to stress, a finding that tells us more about the human-dog relationship and could have applications in dog training. anxiety and PTSD assistance. who are currently trained to respond primarily to visual cues.

The authors add: “This study demonstrates that dogs can distinguish between breath and sweat sampled from humans before and after a stress-inducing task. This finding tells us that an acute, negative, psychological stress response alters the odor profile of our breath/sweat, and that dogs are able to detect this change in odor.”

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More information:
Dogs can distinguish between human base odors and psychological stress odors, PLOS ONE (2022). DOI: 10.1371/journal.pone.0274143

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