Skip to main content

Verified by Psychology Today


Dogs Really Can Tell When You're Stressed

Research continues to reveal what dogs can sniff out.

 Rodnae Productions / Pexels Free Download
Source: Rodnae Productions / Pexels Free Download

Everyone knows that dogs know what we're thinking and feeling, often before we do. They also can sniff out various diseases. Usually, their highly evolved noses, sophisticated smelling machines, are the source of this knowledge; they also use visual cues such as our facial expressions and movements and can tell us how we're feeling even when we don't know how we're feeling.

Last night and this morning I received countless emails telling me that we now know that dogs really can smell when we're stressed. Popular media has jumped on the results of a recent open-access study, "Dogs can discriminate between human baseline and psychological stress condition odours," by Clara Wilson at Queen's University in Belfast and her colleagues. It's worth reporting what they learned.1,2 As the researchers put it, they "studied whether dogs trained on a scent discrimination paradigm could discriminate between the breath and sweat combined samples taken from human participants at baseline and when they were experiencing an experimentally induced state of psychological threat." The participants were asked to solve mental arithmetic problems, which can be highly stressful.

The researchers trained 20 dogs from the Belfast community and four named Treo, Fingal, Soot, and Winnie were actually used to test how well they could detect stress using operant conditioning and positive reinforcement. The four dogs were exposed to 36 breath and odor samples collected from 30 females and six males and were able to discriminate between samples taken at a baseline level when the people weren't stressed and when they were.

What Do We Really Know?

Although only four dogs were ultimately studied, the data are robust. We now know what we've known for a long while, namely that dogs can sniff out our psychological states.

What about other aspects of dog behavior including their emotions? What do we really know? For a long time, many people doubted that dogs feel jealousy, but two detailed studies show they do. Another myth that continues to be circulated: dogs don't feel guilt. However, this is a misinterpretation of a study that showed how humans are not good at reading guilt, not that dogs don't feel guilt. We still don't know if they do. Yet given what we know about their rich and deep emotional lives, it wouldn't be surprising to learn that they do.3

While we've known that dogs are able to sniff out our feelings, we need studies such as this Queen's University research to verify what we intuit. I look forward to further studies on dogs' abilities to read and sniff us and how they and we can use this information to foster and maintain better dog-human relationships.

Facebook/LinkedIn image: Jan Bray/Shutterstock


1) Numerous popular media reports can be seen here.

2) The abstract for this study reads, "Previous research suggests that dogs can detect when humans are experiencing stress. This study tested whether baseline and stress odours were distinguishable to dogs, using a double-blind, two-phase, three-alternative forced-choice procedure. Combined breath and sweat samples were obtained from participants at baseline, and after a stress-inducing (mental arithmetic) task. Participants’ stress was validated with self-report and physiological measures recorded via a Biopac MP150 system. Thirty-six participants’ samples were presented to four dogs across 36 sessions (16, 11, 7 and 2 sessions, respectively). Each session consisted of 10 Phase One training trials and 20 Phase Two discrimination trials. In Phase One, the dog was presented with a participant’s stress sample (taken immediately post-task) alongside two blanks (the sample materials without breath or sweat), and was required to identify the stress sample with an alert behaviour. In Phase Two, the dog was presented with the stress sample, the same participant’s baseline sample (taken pre-task), and a blank. Which sample (blank, baseline, or stress) the dog performed their alert behaviour on was measured. If dogs can correctly alert on the stress sample in Phase Two (when the baseline sample was present), it suggests that baseline and stress odours are distinguishable. Performance ranged from 90.00% to 96.88% accuracy with a combined accuracy of 93.75% (N trials = 720). A binomial test (where probability of success on a single trial was 0.33, and alpha was 0.05) showed that the proportion of correct trials was greater than that expected by chance (p < 0.001). Results indicate that the physiological processes associated with an acute psychological stress response produce changes in the volatile organic compounds emanating from breath and/or sweat that are detectable to dogs. These results add to our understanding of human-dog relationships and could have applications to Emotional Support and Post Traumatic Stress Disorder (PTSD) service dogs."

3) For more discussions of myths about dogs click here.

Dogs Watch Us Carefully and Read Our Faces Very Well.

Can Dogs Tell Us We're Angry When We Don't Know We Are?

Jealousy in Dogs: Brain Imaging Shows They're Similar to Us.

Dogs Know When They've Been Dissed, and Don't Like It a Bit.

Dogs and Guilt: We Simply Don't Know.

Trust and Cooperation are Widespread Among Diverse Animals.

Cook, Peter et al. Jealousy in dogs? Evidence from brain imaging. Animal Sentience, 2018.

More from Marc Bekoff Ph.D.
More from Psychology Today