Two of dogs’ greatest attributes are their acute sense of smell – about 10,000 times that of humans – and their incredible empathy. A new study published in PLOS One shows canines can utilize both these abilities to sniff out stress.
Stress Has a Smell That Dogs Can Detect
Stress causes physiological changes, including alterations in breath and sweat compounds, which produce distinct odors. Stress-induced sweat also primarily secretes from apocrine glands, which tend to create more aroma than eccrine glands, which secrete most heat-induced sweat.
Researchers from Queen’s University in Belfast, United Kingdom, set out to see if dogs could tell the difference. They collected sweat and breath samples from participants before and after they completed stressful tasks. Then, they tasked dogs trained in scent identification with distinguishing between the two. The canines did so accurately in 675 of 720 trials – or about 94 percent of the time.
“While it is likely that in a real-life context, dogs are picking up on our stress from a variety of context cues, we have shown using a laboratory study that there is a confirmed odor component that is likely contributing to dogs’ ability to sense when we are stressed,” Clara Wilson, an animal psychologist, and the study’s lead author wrote, per NBC News.
Why It Matters That Dogs Can Sense Stress
Previous research has shown how dogs perceive and often mirror human emotions, particularly their parents’. Scientists also know dogs can smell disease, including COVID-19 and cancer, by detecting volatile organic compounds (VOCs). However, this is the first study illustrating how dogs can detect stress through scent.
Wilson said that we need more research to determine how significant dogs’ sense of smell is in deciphering human emotions. But Wilson and her colleagues wrote their findings could be valuable in training anxiety and PTSD service dogs, whose instructors presently train them to respond to primarily visual cues.
