When momma ain’t happy, ain’t nobody happy—including the dog.

That’s what new research out of Scandinavia suggests.

Scientists from Linkoping University in Sweden published a study last week in the journal Scientific Reports that indicates dogs who have stressed-out owners are more likely to be stressed out, too.

So it’s not just momma, it’s also poppa and everyone else in the family who might have an ownership stake in the dog.

The study focused on the presence of the hormone cortisol, a chemical released into the bloodstream and absorbed by hair follicles in response to stress.

The researchers collected hair samples from 58 dogs and their owners, then measured the concentration of cortisol in both groups. Although cortisol can show up in blood, urine, or saliva tests, the researchers say that cortisol levels in hair can give a longer-term picture of overall cortisol levels in the body.

The dogs also wore computer-linked collars to monitor their activity for one week.

Meanwhile, owners filled out questionnaires that asked them to rate themselves on qualities such as agreeableness, extraversion, and neuroticism. They also answered questions about their dogs’ personalities: levels of excitement, aggression, responsiveness to training, and how afraid they were of other dogs.

The findings showed that if an owner had high levels of cortisol, so did their dog. Researchers observed this pattern both in winter and summer, when cortisol levels can differ. Researchers call this correlation of cortisol levels synchronization, and say it was particularly strong in female dogs.

NEWStat asked Lina Roth, PhD, a researcher at Linkoping University and lead author of the study, why female dogs showed the effects of stress more strongly than males.

“Females have been suggested before in several species to show higher emotional responsivity due to different social roles,” Roth said. “So that might be one reason behind the stronger synchronization.”

Depression, excessive physical exercise, and unemployment are just a few examples of stress that can influence the amount of cortisol found in your hair, Roth said.

Roth thinks owners are influencing the dogs rather than the other way around because several human personality traits appear to affect canine cortisol levels.

Roth admits that her team doesn’t know precisely why humans stress levels are affecting dog stress levels and that we need to be cautious about drawing too many conclusions without more research, “but one speculation could be that we, as owners, are a more central part of the dog’s life and its social supporter, while humans also have other social networks outside [of] home.” Which means that dogs are much more emotionally dependent on how people act around them than the other way around. She added that, “Dogs are also very skilled in picking up our signals, both intentional and unintentional.”

So how can dog owners reduce stress levels in their dogs, especially if the owner’s stress is what’s spiking those stress levels in the first place?

“Spend time with your dog, and interact in a way that you both appreciate,” Roth said. “Play is also found to have a beneficial effect on stress levels—so have fun!”

Photo credit: © iStock/verbaska_studio