Dogs Can Smell When We’re Stressed Out, New Study Shows

It’s long been widely believed that dogs can detect extreme emotions by smell. Now scientists at Queen's University Belfast in the U.K. have proven that a dog's nose knows.

Acute stress changes the compounds found in human sweat and breath, research has shown. For the new experiment, four dogs were presented with sweat and breath samples collected from human volunteers — before and after the people engaged in a difficult math exercise.

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The canine participants were able to detect with a greater than 90% accuracy which samples came from before and which came from after the 36 human volunteers had spent three minutes trying to count backward, aloud, from 9,000 in units of 17, according to the report published Wednesday in the scientific journal PLOS One.

“This study provides further evidence of the extraordinary capabilities of ‘man’s best friend,’” said the study’s first author, animal psychologist Clara Wilson.