"Cortisol is incorporated in hair as it grows, so we get kind of a retrospective of our cortisol secretions," Roth explains.
They found that dog cortisol levels seemed to mirror the personality traits of their owners.
"It was the owner's personality that influenced the dog's hair cortisol level, rather than the dog's personality itself," Roth says. The correlation was stronger between dogs and owners who compete together than it was between owners and dogs who don't.
"When it comes to competing dogs, it could actually be that they spend more time together, and that this training could increase this emotional closeness," Roth speculates, though she adds that "this is a correlation, so we really don't know the mechanism behind this."
Roth says she would like to do follow-up studies looking at more dog breeds — this research focused on border collies and Shetland sheepdogs. She is also interested in how owner gender might influence the results. This study included only female owners.
Rosemary Strasser, a behavioral neuroendocrinologist at the University of Nebraska, Omaha, who has studied connections between dogs and humans, says the new research is exciting and that it raises further questions about how dogs and humans influence each other emotionally.
One big question: Could dogs also influence human stress levels over time? "Especially with dogs being used as service or support dogs for individuals," Strasser says, "if you place a confident, outgoing dog in a home, how does it influence the personality of that owner? Is it always one-directional? That would be a very interesting further extension of this."
Previous research has suggested that the personality and attitude of a dog owner can influence how emotionally attached that person becomes to their pet. "A person who likes dogs and wants a dog will interact with that dog differently than a person who may be given or exposed to a dog that they don't necessarily want," Strasser says.
Both researchers caution that dog owners should not read the new research results and worry that their personalities are harming their animals. The study doesn't suggest, for example, that neurotic humans are causing their dogs to act neurotically, as well.
"I don't think you should be anxious that, if you're stressed, you might harm your dog," Roth says. "Instead, your dog is a social support for you, and you are a social support for the dog."
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