t is simple to your dog to know if you happen to’re stressed, and that is because it could smell it in your breath and sweat, in line with a recent study.

Previous studies have suggested that dogs can tell if persons are stressed, a team of researchers wrote of their study, published Wednesday in PLOS (Public Library of Science) ONE. Since dogs are known to have an incredible sense of smell, the researchers sought to seek out whether may very well be sensing the stress through chemical signals, PLOS noted in a news release.

So for his or her work, the researchers conducted an experiment to see whether dogs can differentiate between human odors at baseline (neutral) and after they’re under stress. To do that, they collected breath and sweat samples from participants at baseline and after they’d undergone a stress-inducing arithmetic task. Their stress was also validated through self-report, in addition to measures reminiscent of their blood pressure and heart rate.

Samples from 36 participants were presented to trained dogs inside three hours of being collected.

“In Phase One, the dog was presented with a participant’s stress sample (taken immediately post-task) alongside two blanks (the sample materials without breath or sweat), and was required to discover the stress sample with an alert behavior,” the researchers explained. “In Phase Two, the dog was presented with the stress sample, the identical participant’s baseline sample (taken pre-task), and a blank.”

This photo shows the dogs through the experiments.

The thought is that if the dogs could appropriately discover the stress samples in Phase Two, when the baseline samples of the participant were also around, then the baseline and stress odors were actually distinguishable to them, the researchers explained.

Incredibly, the dogs were individually capable of detect the stress samples and perform the alert behavior with a formidable accuracy starting from 90% to 96.88%. Their combined accuracy was 93.75%. This, in line with the researchers, is “greater than expected by probability.”

“While the dogs on this study underwent training as a way to communicate that they were able to differentiate between odors, the found performances on this task suggests that there are VOC (volatile organic compound) changes induced by acute negative stress which might be detectable by dogs,” they wrote.

In other words, the outcomes suggest that dogs can actually detect the changes in people’s breath and sweat after they’re psychologically stressed, and so they can accomplish that “with a high degree of accuracy.”

Not only does this shed further light on the connection between dogs and humans, but they are saying it might also have implications for service dogs that, in line with PLOS, are up to now trained to reply mainly to visual cues.