Dogs Can Smell When You’re Stressed

By Caroline Coile

We’ve heard it countless times: “Dogs can smell fear.” Now a study from Queen’s University Belfast has produced some actual evidence that dogs can in fact sniff out stress. Here’s what they did:

First the researchers trained four dogs to match an odor sample to a target odor sample. The dog was presented the target odor through a sniffing apparatus, then chose the one of three other samples that matched it.

The researchers then stressed out 36 human subjects by having them solve difficult math problems. They confirmed the subjects’ stress level with measures of heart rate, blood pressure and self-report. When those measures indicated the subjects were stressed, the researchers then took samples of their sweat and breath. They used one stressed sample as their target odor and presented the dogs with the choice of a matching stressed sample, a sample from the same person taken when unstressed, and a blank unscented sample. The dogs were able to choose the matching stressed sample from the same subject’s relaxed sample with 94% accuracy (675 out of 720 trials).

This was a double-blind study in which nobody in touch with the dogs knew which sample was which. In addition, the dogs had no access to the human subjects so they could not base their responses on visual or auditory cues. The results are consistent with the idea that dogs can detect the differences in volatile organic compounds known to exist in the breath and sweat of stressed people, and that they can use these cues to detect when a person is stressed—even if they cannot see or hear them.

This information is important for various service and emotional support dogs, particularly for dogs trained to calm handlers with PTSD. Having a more objective and consistent way to train these dogs could make training easier and more reliable. As for those of us competing in dog shows, agility trials and other venues where we question why our dogs seem to be ringwise—maybe they are just wise to our stress!

Wilson et al. (2022) Dogs can discriminate between human baseline and psychological stress condition odours | PLOS ONE

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Posted by Liz on Dec 27 2022. Filed under Current Articles, Featured. You can follow any responses to this entry through the RSS 2.0. Both comments and pings are currently closed.