Ruff day? Dogs can detect if people are stressed, research finds

Life is full of stress, whether it is a math problem or a bill. Humans and dogs can smell the same when under pressure.

Questions remained over whether dogs could detect stress through scent or if they could do it through smell.

The first author of the research was Clara Wilson, a PhD student at Queen's University.

Wilson said the findings could be useful when training service dogs for people with Post-Traumatic Stress Disorder.

Wilson said that they are trained to look at someone crouching down on the floor.

She said that the latest study could be a cue.

Wilson said that the smell component could be useful in the training of the dogs.

Wilson and colleagues wrote about how they built a stand with three containers, each topped by a lid.

Four dogs were trained to identify the container holding a particular breath and sweat sample, even when the line-up included unused gauze, samples from another person, or samples from the same person taken at a different time of day.

The team collected breath and sweat samples from 36 people who were asked to count backwards from 9,000 in units of 17. The 27 people who carried it out in the lab had their blood pressure and heart rate go up.

The dogs were taught to pick out the samples from the line-up that included two containers.

When the line-up included samples taken from the same person just before the task, the researchers were able to see if the dogs could do it. The samples were shown to a single dog.

Out of the 720 trials, the dogs chose the sample with the highest stress level.

Wilson said it was amazing to see them tell him that the two things were not the same.

The study shows that humans produce a different smell under stress, which is consistent with previous research that used instruments to analyse samples.

While the dogs were trained to tell apart different samples, it is possible that untrained pet dogs can detect changes in smell when a human is stressed.

The medical alert assistance dogs were trained to alert people with complex health conditions when they were in danger of having a potentially life-threatening medical event by detecting changes in their health.

She said that some of the conditions are thought to be due to a change in hormone levels, as that can also be linked to hormonal fluctuations.