Dogs mirror owner’s stress level

Stress is contagious – at least when talking about acute stress. Several studies have shown that humans are affected by each other's stress levels. A mother’s stress is transmitted to her youngsters, and students are influenced by a tense lecturer.

The transmission of stress levels even seems to occur between animals. Acute stress has also been shown to spread from man to his best friend, the dog.

But what about chronic stress, meaning a high stress level over a prolonged period?

Recently, Swedish researchers investigated just that.

Their results show that human stress levels probably influence their dog’s condition. But not the other way around.

Hair revealed stress

So, how can we find out if people or dogs are experiencing long-term stress?

Measuring the levels of the stress hormone cortisol in blood or saliva samples is an easy way to determine acute stress. But this method is impractical for knowing how things are going for longer periods. Fortunately, the researchers have something better up their sleeve:

Hair.

Cortisol is contained in the hair shaft, and over time the strands of hair provide a chronological overview of the body’s cortisol levels. Using hair strands from dogs and their owners thus enables researchers to compare and analyse the long-term stress level.

58 dogs and owners

Researcher Ann-Sofie Sundman and her colleagues recruited 58 pairs of dogs and their female owners. Thirty-three of the dogs were Shetland Sheepdogs and the rest were Border Collies. Some were purely pets, while others were actively involved in competition.

In addition to the hair samples, the researchers mapped personality traits in both the dogs and the humans, using questionnaires answered by the owners. The dogs also wore activity metres for a week.

Sundman and her team took measurements both in the winter and summer, in order to determine whether seasonal variations had any impact on stress levels.

Owners affected their dog

The results showed that the owner’s stress level clearly seems to impact the stress level in the dog. The owner's personality also seems to play a role.

However, it appears that the dog’s activity level did not have any bearing on long-term stress. And there was little indication that the dogs' stress level and personality had any effect on their owners.

Researchers can’t yet say whether these findings apply to all dog breeds. Nor can they say whether male owners would have the same effect on the dog's stress level, since all the owners in the survey were women.

It should also be mentioned that the questionnaire, used to measure the personality of both the owners and the dogs, raises some uncertainty.

All in all, the researchers concluded that dogs to a great extent mirror the stress level of their owners.

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Read the Norwegian version of this article at forskning.no