Dog owner's take note! Your furry friend may be get affected by your stress, as scientists have found that pooches mirror humans' stress level.
Researchers at Linkoping University in Sweden have examined how stress levels in dogs are influenced by lifestyle factors and by the people that the dogs live with.
They determined stress levels over several months by measuring the concentration of a stress hormone, cortisol, in a few centimetres of hair from the dog and from its owner.
"We found that the levels of long-term cortisol in the dog and its owner were synchronised, such that owners with high cortisol levels have dogs with high cortisol levels, while owners with low cortisol levels have dogs with low levels," said Ann-Sofie Sundman from Linkoping University.
The study, published in the journal Scientific Reports, examined 25 border collies and 33 Shetland sheepdogs, all of them owned by women.
The owners and the dogs provided hair samples on two occasions separated by a few months.
Since physical activity can increase cortisol levels, the researcher also wanted to compare companion dogs with dogs that competed in obedience or agility. The physical activity levels of the dogs were therefore recorded for a week using an activity collar.
Previous research has shown that levels of short-term cortisol in saliva rise in a synchronous manner in both the dog and its owner when they compete together.
The new study, in contrast, found that physical activity in dogs does not affect the long-term cortisol in their hair. On the other hand, the stress level of competing dogs seems to be linked more strongly with that of the owner.
The scientists speculate that this may be associated with a higher degree of active interaction between the owner and the dog when they train and compete together.
The dog owners were also asked to complete two validated questionnaires related to their own and their dog's personality.
The result suggests that the match between an owner and a dog affects the dog's stress level.
Further studies are, however, needed before we can draw any conclusions about the cause of the correlation. The researchers are now planning to study other breeds.