Perhaps that chestnut about dogs being man’s best friend needs a tweak. It’s the bitches that feel your pain, while the males are more likely to shrug their furry shoulders and carry on, according to a newly published study titled “Long-term stress levels are synchronized in dogs and their owners.”
The headline doesn’t distinguish between doggie genders and their susceptibility to empathic stress — and indeed both male and female canines have an unwitting synchronization with their feeders. But the females were, generally, more in sync with their stressed-out owners, according to the study published Thursday in Nature: Scientific Reports.
Social animals in general could be expected to sense each other’s stress and get “infected” by it. Stress-sharing has, it turns out, been demonstrated in prairie voles. Separate research has even found that rodents may freak out at the smell of males, including men, becoming relatively more stressed if the scientist is non-female, which can skew behavioral tests.
But back to dogs. There are a few issues with the study: It is very small in scope, in terms of absolute numbers of participating dogs, owners and species. The study involved exactly 33 Shetland sheepdogs and 25 border collies and their human owners — “58 dyads” — to determine their stress levels over a year, and whether the owner’s stress level correlated to that of their dog.
On the other hand, the research by Lina Roth and colleagues from Sweden’s Linköping University involved a wide range of circumstances: season, sex of owner, age of owner, pet dogs versus working dogs, sex of dog, lifestyle, and more, including innate neuroticism.
How did they gauge chronic stress in the pets? By measuring the concentration of cortisol in their fur.
Cortisol is an indicator of the body’s hormonal responses to stress and is more commonly measured in saliva, urine or blood — but those are measures of acute stress. Cortisol levels in our bodily fluids also fluctuate by day or night, rendering the timing of collection critical.
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Hair cortisol, on the other hand, is a much better proxy indicator of long-term, chronic stress, so that is what the Swedish scientists checked.
Season can also affect cortisol levels. However, these fluctuations did not affect the synchronization of stress.
Of course, there are plenty of things that can stress Fido that have nothing to do with you. This is a study about how you affect your dog.
Which begs the question, what if some of those 58 dogs were just perennial nervous wrecks, irrespective of their owners’ emotional states?
The scientists corrected for that: “The personality traits of both dogs and their owners were determined through owner-completed Dog Personality Questionnaire (DPQ) and human Big Five Inventory (BFI) surveys,” they report.
These questionnaires are probably not objective, either about the owners’ personalities or those of their pets. As some sort of control to the bias of perception, the dogs’ activity levels were monitored using “a remote, cloud-based activity collar” for a week (though any pet owner can tell you that dogs have their ups and downs).
The result: Elevated stress in the owner was correlated to elevated cortisol in their dogs — especially in female dogs, mean age 4.7 years. (The mean age of the owners was 46.)
This was not some strange artifact of long-night depression in the northern winter. “The association between stress in dogs and humans was also observed in both summer and winter, suggesting that seasonal fluctuations in cortisol levels did not affect the synchronization of stress,” the team writes.
Given that some people think their dog understands everything they say, our opinions of our loved ones are suspect. Arguably, not even one’s spouse understands everything one says, let alone one’s husky.
But keeping the questions broad can be helpful. The bottom line is that the dogs’ personalities (as seen by their doting owners) didn’t have much to do with their cortisol levels. It was the personality of the owners that caused differences.
By and large, conscientiousness, openness and neuroticism in the owners affected the dogs’ cortisol levels. Ergo, dogs seem to mirror the stress level of their owners. Especially the female dogs, and competition dogs.
No, the owners are not reflecting their dogs’ stress.
People and dogs have been living together for at least 14,000 years and, leaving zoonotic parasites out of it, they can be pretty good for us. A study also published in Nature: Scientific Reports in April found that English dog owners are estimated to be four times more likely than non-dog owners to meet recommended physical activity guidelines. Again, the study was not exactly huge: 191 dog owners, 455 non-dog owners, all living in West Cheshire. The chief activity the owners did more of was dog-walking. Nu.
In Tel Aviv, the craze among urban professionals is to hire professional dog walkers, who presumably gain the health benefit — there’s food for thought.
“Even small effect sizes might contribute considerable additional physical activity at the population level provided, of course, that the dogs are actually walked,” the study observes. Quite.
Other recent research indicates that, in contrast to popular thinking, neither our shepherd dogs or Chihuahuas are recent descendants of the wolf. Dogs and wolves were and are distinct species that seemingly had a common ancestor perhaps around 40,000 years ago. Wolves are not known for that touchy-feely sharing thing. You can keep one in your house from cub-hood and it may still eat you if it gets hungry.
So might your Pomeranian, but chances are it will feel your stress before it digs in.