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Ruff tag? Research Shows Dogs Can Tell When People Are Stressed | Science

Whether it’s a tricky math problem or an unexpected calculation, everyday life is full of stressful experiences. Now researchers have found that people produce a different smell under pressure – and dogs can sniff it out.

While previous studies suggested that dogs might be able to detect human emotions through smell, the question remained whether they can detect stress and if this could be done through smell.

“This study has definitely proven that people’s olfactory profile changes when they respond to stress,” said Clara Wilson, a PhD student at Queen’s University Belfast and the study’s first author.

Wilson added that the results could prove useful when training companion dogs, such as those that support people with post-traumatic stress disorder (PTSD).

“You’re often trained to look at someone who’s either crouching on the floor or starting to hurt themselves,” Wilson said.

The latest study, she said, offers another possible clue.

“There’s definitely an olfactory component, and that could be valuable in training these dogs on top of all the visual stuff,” Wilson said.

Writing in Plos One magazineWilson and colleagues report how they first constructed a stand with three containers, each with a perforated lid.

The researchers report that they were able to train four dogs to display the container with a specific breath and sweat sample, even when the lineup included unused gauze, samples from another person, or samples from the same person taken at a different time of day.

Confident that the dogs understood the approach, the team turned to breath and sweat samples collected from 36 people who were asked to count backwards from 9,000 in increments of 17. In the lab, their blood pressure and heart rate increased on.

The dogs were taught to select samples taken immediately after the task from a row containing two containers of unused gauze.

The researchers then tested whether the dogs could do the same if the lineup included not just unused gauze, but samples taken by the same participant just before the task, when they were more relaxed. Each sample set was presented to a single dog in 20 trials.

The results show that the dogs chose the “stressed” sample in 675 of the 720 trials.

“It was pretty amazing to see them so confidently tell me, ‘No, those two things definitely smell different,'” Wilson said.

The team says that while it was unclear what chemicals the dogs are ingesting, the study shows that people produce a different smell when they are stressed – confirming previous research using instruments to analyze samples.

Wilson added that while the dogs were trained to communicate, that they can distinguish different samples from one another, it’s possible that even untrained domestic dogs can detect changes in smell when a human is stressed.

Claire Guest, co-founder and scientific director of the Medical Detection charity dogswho was not involved in the research, said medical assistance dogs were trained to alert people with complex health conditions when they were at risk of suffering a potentially life-threatening medical event by detecting changes in their scent.

“Some of these conditions are thought to be due to a change in hormone levels, so we’re not surprised to learn that [dogs] can recognize when people are experiencing stress [as that can also be linked to hormonal fluctuations]She said.

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