In the presence of an animal like a dog, the popular belief is that they can feel “fear”. If scientists are not yet unanimous on the subject, a study by Dr Claire Wilson of the University of Belfast has highlighted “the smell of stress. According to the results of this research, published in the journal plos one, the human body emits a very particular smell during phases of acute stress.

Still according to this same study, this smell, undetectable for humans, could be smelled by animals such as dogs. If the use of “man’s best friend” to fight post-traumatic stress or panic attacks is already widespread, the latter could have a scientific explanation.

A small study that confirms

Of the 36 samples used by Dr. Claire Wilson’s teams, the dogs were successful in 90% of cases. In a second exercise, the success rate was even better, reaching 96%. This remarkable accuracy confirms previous studies that were already trying to prove the ability of dogs to sense stress.

According to Dr. Claire Wilson, in charge of this study, such precision in the results shows that dogs are able to tell the difference between a stressed person and another who is not. This could be very useful for training emotional support dogs.

The dog: the solution to combat stress

Today they only work from visual signs but taking into account the highly developed sense of smell of dogs could allow them to be better trained. Dogs would then be even more important in the treatment of these very difficult to spot psychological illnesses. Since humans cannot detect stress as well as dogs, reactions are sometimes delayed, which can have serious consequences for the patient, who is sometimes unable to self-diagnose.

From a chemical point of view, stress is characterized in humans by an increase in heart rate and blood pressure. Changes that have consequences in the smell of breath and perspiration. With a higher heart rate the level of oxygen in the blood and the level of exhaled carbon dioxide are not going to be the same.

The nose of dogs: their superpower

Micro-changes that go unnoticed by a human but that the sense of smell of dogs can detect very well. The latest studies on the subject estimate that dogs’ sense of smell is about 1 million times more developed than that of humans. This abysmal difference can be explained in particular by the very design of our olfactory devices.

Despite their size, dogs have a nasal mucosa 50 times larger than that of humans. A major advantage for detecting changes as small as stress.