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At Sci News: Dogs Can Detect when Humans are Experiencing Stress


Odors emitted by the body constitute chemical signals that have evolved for communication, primarily within species.

A sense of smell of dogs and other canines provides critical information, essential for being aware of potential predators, locating food, identifying conspecifics, and enabling recognition of familial members.

Research on chemical signals has extended to explore inter-specific communication, such as that between mice and humans, cows and humans, horses and humans, and canines and humans.

 Image credit: Wilson et al., doi:

Given domestic dogs’ remarkable sense of smell, and their close domestication history with humans, it is possible that they are detecting odors associated with changes within the human body beyond those that have already been established.

The use of dogs to support human psychological conditions such as anxiety, panic attacks and post traumatic stress disorder (PTSD) is growing in popularity, with waiting lists for PTSD service dogs being months-to-years long in some instances.

Such dogs have been reported to improve an individual’s quality of life, social connections, and reduce the number of panic attacks or PTSD symptoms, with the tasks of ‘calming’ and ‘interrupting anxiety’ reported as the most helpful part of their behavioral repertoire.

However, empirical evidence for what mechanisms dogs may be utilizing to respond to their owner’s psychological experience is currently lacking.

“Our 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 lead author Clara Wilson, a Ph.D. student in the School of Psychology at Queen’s University Belfast.

Overall, dogs could detect and perform their alert behavior on the sample taken during stress in 675 out of 720 trials, or 93.75% of the time, much greater than expected by chance.

The first time they were exposed to a participant’s stressed and relaxed samples, the dogs correctly alerted to the stress sample 94.44% of the time. Individual dogs ranged in performance from 90% to 96.88% accuracy.

“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 to the training of anxiety and PTSD service dogs that are currently trained to respond predominantly to visual cues,” the authors said.

“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.”

The study was published in the journal PLoS ONE.

Full article at Sci News.

The first sentence of this article includes an (obligatory?) genuflection to the putative powers of “evolution.” As a scientist, it seems unscientific to ascribe an effect as complex as communication/signaling via odor detection and interpretation to evolution, when the naturalistic mechanisms to generate the novel information for such a feat is questionable at best.

Caspian, dogs smell if you like them or better love them, are afraid of them, dislike them. I think they can figure our key bits of what we say. They read our emotions. I have seen them use their eyes to communicate far beyond wagging tails and more. I understand they can smell cancer. There was the dog that scratched on a neighbour's car, marking where mice built a nest that threatened electricals. They really are our friends. There was a dog that stood vigil over its owner's grave for years, in Scotland. And more, as faithful as a dog is truth. KF kairosfocus
Interesting this has been known for years and what’s amazing is they can know with out training or prompting. My friends dog maverick loves me and I lived with them for a bit when things were bad for me. That dog new immediately I was having issues and would not leave my side. It was the first time I ever liked a German shepherd. If I could steal maverick I would AaronS1978

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