Previous studies have already suggested that, thanks to their sense of smell, dogs are able to detect when a human is stressed. But providing an accurate assessment of this ability requires a rigorous protocol to know how well these animals distinguish a person’s scent when normal and when anxious. A study from Queen’s University of Belfast (Northern Ireland), published on September 28, 2022 in the journal Plos Onedelivers particularly interesting and precise results.
When stress reveals itself in breath and sweat
Dogs have 300 million olfactory receptors. Useful for locating food or congeners, their power is now largely diverted by humans. For example, dogs have been trained to detect small amounts of gasoline, diseased trees, cancers, and even coronavirus infection. “Given dogs’ remarkable sense of smell and their history of close domestication with humans, it is possible that they detect scents associated with changes in the human body beyond those already established.“, warn the authors of this new study.
Of all the uses of the dog, one in particular is developing: its use as an emotional support to alleviate the anxiety of a designated person. Recently, it was at the Marseille Criminal Court, during the trial of the Millas tragedy, that two legal assistance dogs demonstrated their empathy. “However, empirical evidence of the mechanisms dogs may use to respond to their owner’s psychological experience (or strangers, editor’s note) currently default font“, note the authors of this new study.
In humans, stress leads to the release of adrenaline and cortisol into the blood, increased heart rate, blood pressure and respiration. Another important phenomenon adds to these adaptations: cells release volatile organic compounds (VOCs) during their work. Some of these VOCs, found in exhaled air and in sweat, reflect an increase in stress. However, researchers do not agree on concerned. No matter, according to the authors of this new study: dogs are able to smell certain VOCs. So if they react differently when sniffing those emitted by a person in an ordinary mood, and from this same person when she is stressed, it is because a detectable physiological difference for canids is taking place.
Mental calculation to destabilize the participants
Samples of expired air (by blowing several times into a bottle that was then closed) and sweat (by passing a compress on the neck) were obtained from 36 participants while they were in a normal state or under stress from a mental calculation exercise.