Emotional contagion: When your stress becomes your dogs stress, too

The human-animal bond might go deeper than we think, a new study claims. As a veterinary professional, you probably have loads of anecdotal evidence to support this claim-now you have proof.

“This study reveals, for the first time, an interspecific synchronization in long-term stress levels,” the study authors state. In other words, we now have evidence that dogs actually do mirror their owners when experiencing long bouts of stress. Take a deep, calming breath and let's dig into it.

On the basis of sex

While the HCCs of both male and female dogs was synchronized, the study states, the association was stronger in female dogs. Not only that, but the study found that female dogs in general showed higher cortisol concentrations than male dogs, suggesting that female dogs have a higher emotional responsivity. In other words, a dog's sex does affect hormonal synchronization.

How they did it

As you probably already know, when a human or pet is stressed, cortisol is released into the bloodstream and absorbed by hair follicles. The researchers of this study surveyed 58 people who own border collies (n=25) or Shetland sheepdogs (n=33), mainly by examining hair cortisol concentrations (HCCs) from both owners and dogs.

According to the study, headed by a team from Linköping University in Sweden, dogs' and owners' HCCs were analyzed on two separate occasions: once during the summer and once during the winter. At the same time, personality traits of the dogs and their owners were analyzed using a Dog Personality Questionnaire (DPQ) and a Big Five Inventory (BFI) survey, respectively. Additionally, the study states, the dogs' activity levels were monitored continuously with a remote cloud-based activity collar for one week.

What they found

Significant correlations were found between dogs and humans with regard to long-term stress. “Interestingly,” the study states, “the dogs' activity levels did not affect HCC, nor did the amount of training sessions per week, showing that the HCC levels were not related to general physical activity.” In other words, stress did all the work.

In addition, results showed that although the dogs' personalities themselves had little effects on their HCCs, the study says, personality traits of their owners significantly affected the dogs' HCCs. “Since the personality of the owners was significantly related to the HCC of their dogs,” they write in the study, “we suggest that it is the dogs that mirror the stress levels of their owners rather than the owners responding to the stress in their dogs.”

Why this matters

So what does this mean for the human-animal bond? For starters, that depends on whether your dog is a pet or a competing animal. The researchers of this study found that prize-winning dogs have a stronger cortisol synchronization than pet dogs do. This may, the study says, be due to the fact that competing owners and dogs spend more time together engaging in the same tasks.

Another thing to note is the personality of the pet owner. According to the study, neuroticism, openness and conscientiousness influence long-term cortisol concentrations in dogs. Owners who scored high on neuroticism formed a strong attachment to their dogs and use their dogs for social support, all while simultaneously functioning as a social supporter for their dog. (Does this sound familiar? It's because similar results were found with cats and their owners.) 

At the end of the day, if you're feeling stressed, your dog's probably feeling it also. So, after a particularly rough day, be sure to give your pet a good head scratch-and maybe give yourself one, too.