Why Don't You Unwind by Taking Me for a Walk?

A study from Queen's University Belfast looked at the ability of dogs to 'sniff out' human stress (https://www.theguardian.com/science/2022/sep/28/dogs-can-detect-people-stressed-research-odour-profile). Four dogs were trained. A stand was employed with 3 containers, each with a perforated lid. The dogs were able to distinguish a container holding a gauze sample impregnated with human sweat and breath from e.g., one holding unused gauze. 36 human subjects were then stressed by being asked to count backwards from 9000 in units of 17. All subjects reported they found this task stressful. 27 confirmed this, by showing increases in blood pressure and heart rate. Just after the task, gauze samples exposed to breath and sweat, were taken from each subject. The dogs were easily able to pick out this sample, when the other 2 containers held unused gauze. These canine Sherlocks could also, however, indicate the stressed sample, when the alternatives included a sample from the same participant, taken just before the task. Subjects, at this time, were more relaxed and presumably smelt different. These dogs actually made a correct choice in almost 94% of trials. Clearly, stress changes human odours and trained dogs can 'sniff out' this alteration. This stress-detecting ability could prove useful, when dogs are employed to deal with emergency situations or used to calm humans.