Stressed Out Owners Are More Likely to Have Stressed Out Dogs, Scientists Believe

Dogs who have stressed owners are more likely to be stressed too, according to scientists. Swedish researchers looked at the levels of a stress hormone in 58 dogs and their owners to arrive at their conclusion.

The team behind the findings published in the journal Scientific Reports collected the hair of 33 Shetland sheepdogs, 25 border collies, and their masters in the summer and winter. They then measured levels of cortisol, a hormone released during stress. Hair gives a longer-term picture of cortisol levels in the body, when compared to something like blood or saliva, the authors argued. Variables including breed, sex, and whether the animal was just a pet or used in competitions was also considered. The dogs also wore collars linked to a computer cloud to monitor their activity for one week.

The human participants also filled out questionnaires on their own personality traits, like agreeableness, extraversion, and neuroticism. For their dogs, they answered questions on their levels of excitement, aggression, how responsive they were to training, and how afraid they were of other dogs.

If an owner had high levels of cortisol, so too did their dog, the researchers found. This pattern was observed both in the summer and winter, when levels of the stress hormone can differ. The effect was most profound in female dogs.

The amount a dog exercised didn't appear to change the levels of cortisol in their fur, suggesting the cortisol wasn't linked to physical activity, the authors said.

The team also found ties between an owner's reported personality and their dog's emotional state. Owners who were conscientious and open were more likely to have dogs with higher cortisol levels in the winter when compared with other participants; while dogs with neurotic owners had lower cortisol levels. The authors believe this could indicate that a stressed dog won't change its owner's mood.

They wrote that neurotic humans form a strong attachment bond to their dogs, and give and receive more support from the dog than others. "This, in turn, may lead to a positive modulation of the stress response for both parties," the authors said.

But the researchers acknowledged in their paper that questionnaires carry a risk of bias, and participants might not have described their personality or their dog's accurately.

Lina S.V. Roth, study co-author and research fellow at Linköping University, told Newsweek this is thought to be the first study to suggest a long-term synchronization of stress between two different species. Humans have a uniquely close interspecies relationship with the four-legged animals, which has spanned around 15,000 years.

Roth said she was surprised to find there were few associations between a dog's own personality and its long-term stress level, while an owner's personality appeared to have a strong effects on their pet's stress level.

"We do find a stronger correlation between competing dogs and their owners compared to pet dogs and their owners, so one speculation could be that the type of interaction we have with our dog affects our hormone levels," argued Roth.

However, Roth emphasized the study only shows a correlation, and further research is needed to work out the exact mechanisms at play. And as the potential cause remains a mystery, concerned dog owners should simply behave in a way that keeps both parties happy, said Roth.

"Maybe this knowledge could help us match dog and owner that is better for both from a stress-management point of view," said Roth.

Another team of scientists who studied saliva cortisol levels in 132 pairs of dogs and humans during stressful situations simulated in a laboratory setting similarly found owners who scored high for neurotic traits had dogs with lower cortisol levels when compared with participants who didn't. Those findings were published in the journal PLOS One.