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Dogs can smell human stress!

Representational image. A recent study shows that dogs are capable of detecting stress in human beings by smelling their sweat (Pic. Courtesy wikimedia commons)

Bonding of human beings and dogs goes a long way back and it is known that these canines are able to gauge the state of mind and physical well being of their owners. Now a report in sciencedaily.com highlights that stress has a smell and that dogs can detect it from the person’s sweat and breath.

The research was done by scientists of Queen’s University Belfast and it was published in PLOS ONE – a peer-reviewed open access scientific journal.

The subject of the research were four dogs belonging to Belfast and 36 people. The dogs were Treo, Fingal, Soot and Winnie.

Samples of the participants were gathered by the scientists before and after they tried to solve a difficult problem in mathematics. The levels of stress before and after the attempt was reported by the participants on their own. Only those samples were used where the participant’s heart beat and blood pressure had gone up.

The four animals involved in the experiment were trained to explore the line-up of scent and alert the scientists to the right sample.

It was at this stage of the study that the samples pertaining to stress and relaxed stage were brought in. The scientists were not aware if there was a difference in the smell that could be identified by these animals.

During each session of the experiment, each dog was given one individual’s stressed and relaxed samples and these were taken four minutes apart. Interestingly, all the four dogs involved in the test were vigilant and able to bring to the notice of the scientists the stress sample of the individual.

Explaining this, Clara Wilson, the study’s first author said: “The findings show that we, as humans, produce different smells through our sweat and breath when we are stressed and dogs can tell this apart from our smell when relaxed — even if it is someone they do not know. The research highlights that dogs do not need visual or audio cues to pick up on human stress. This is the first study of its kind and it provides evidence that dogs can smell stress from breath and sweat alone, which could be useful when training service dogs and therapy dogs.”

Wilson who is a Ph.D student in the School of Psychology at Queen’s went on to add: “It also helps to shed more light on the human-dog relationship and adds to our understanding of how dogs may interpret and interact with human psychological states.”

Talking about her dog, Treo, a two-year-old Cocker Spaniel who was one of the four dogs involved in the study, Helen Parks remarked: “As the owner of a dog that thrives on sniffing, we were delighted and curious to see Treo take part in the study. We couldn’t wait to hear the results each week when we collected him. He was always so excited to see the researchers at Queen’s and could find his own way to the laboratory.

Parks went on to add: “The study made us more aware of a dog’s ability to use their nose to ‘see’ the world. We believe this study really developed Treo’s ability to sense a change in emotion at home. The study reinforced for us that dogs are highly sensitive and intuitive animals and there is immense value in using what they do best — sniffing!”

Besides Wilson, Kerry Campbell, a M.Sc student in the School of Psychology was part of the study.