Dogs can smell human stress – study

A new study in Northern Ireland shows that dogs' incredible sense of smell can sniff out human stress

Dogs’ noses are things of wonder. They can sniff out a piece of cheese dropped behind a couch in a different county or find the most disgusting thing to roll in for miles around. They can also do useful things for people like detecting drugs, explosives, and even human illnesses like cancer and Covid. And now it seems they can even smell our stress.

That’s the finding of a study by researchers at Queen’s University Belfast in Northern Ireland. It carried out 700 trials with four dogs trained to select one of three scent canisters. Each contained sweat or breath samples from one of 36 human volunteers, whose stress levels were gauged before and after tackling a complex math problem.

Each canister held a sample from either before or after they completed the problem (their blood pressure and heart rate were checked to make sure they were more stressed – some people like mathematics, apparently).

Three canisters were put in front of the dogs – Treo, Fingal, Soot and Winnie – and if they stood still or sat in front of the ‘stressed’ sample, they were rewarded with a treat. In more than 650 of the 700 trials, they did.

"We had lots of evidence that dogs can pick up smells from humans that are associated with certain medical conditions or diseases,” said lead researcher Clara Wilson, “but we don't have much evidence that they can smell differences in our psychological state."

It’s hoped that the study, published in the journal Plos One, will assist in the training of therapy dogs.