Stress is an unavoidable component of modern life. Many people worry about the effect of a stressful lifestyle on their long-term health, but how many of us think about how our lifestyle, and our stress levels, affect the health of our pets?

A new study in Scientific Reports suggests that we should be paying more attention to this since long term stress in dog owners shows a correlation with long term stress in their pet dogs.

The authors of the study, a team of scientists based in Sweden, looked at levels of the stress hormone cortisol, by analysing hair samples from dogs and their owners. Cortisol is stored in hair as it grows in proportion to the amount in the blood, enabling measurement of how stressed someone has been over the months before a sample is taken.

All the 58 dogs used in the study had female owners and were of two breeds – Shetland sheep-dogs and border collies. The study group was also divided up into pet dogs, and those who had been trained for competitions in disciplines such as obedience and agility.

The study used Shetland sheep-dogs and border collies. Credit: Max Pixel
The study used Shetland sheep-dogs and border collies. Credit: Max Pixel

Because the hair samples for each dog-owner pair were taken six months apart, the effect of seasons was also considered, and the activity levels of individual dogs were analysed using a tracking collar for one week during the study. Another aspect considered in this detailed study was the personality of both dogs and dog owners and how they affected each other’s stress responses. This information was obtained by the use of recognised personality surveys, filled in by the owners.

Who affects whom?

The results were fascinating and complex.

For example, it appeared that the personality of the owner can affect the stress levels of the dog, but not the other way around. The study found that seasons affect the cortisol levels of both breeds of dogs, being higher in the winter. Further, training and activity levels did not affect the cortisol levels of the dogs, but that competing dogs had lower cortisol levels in the winter than pet dogs.

One of the most interesting results was that owners with higher stress levels had dogs with higher stress levels in both winter and summer. The authors suggest that this was a causal effect and dogs are responding to the stress levels of their owners.

For many years in the past, humans attempted to deny that animals could feel emotions, believing that emotion separated humans from animals. However, recent work suggests that this is a false idea and that animals as diverse as goats, horses and dogs can not only feel emotions but perceive and respond to them in others.

Credit: Pexels
Credit: Pexels

Given that fact, it is certainly possible that dogs are perceiving and responding to their owners’ stress. The authors of this study imply that this is the case, but do not appear to have looked into shared life events, such as bereavement, ending of relationships, moving of houses, changes in routine, changes in the owner’s employment, or other aspects of life that might have made both dog and owner feel stressed, independently of how the other is feeling.

Admittedly, though, it would be almost impossible to measure the effects of these events on each partner independently of the other, since they are, by definition, closely shared.

Personality traits such as being conscientious seemed to correlate with more stress in dogs, particularly for male dogs. While the owners who claimed they were neurotic personality had male dogs with lower stress levels and female dogs with higher stress levels.

Researchers suggested that the reason for the differing effects of neuroticism may be that females of many mammal species are more responsive to the emotions of others, causing the female dogs to be directly affected by the owners’ anxiety levels. On the other hand, neurotic and anxious people tend to form stronger bonds with their pets, often using them for emotional support, which may make male dogs feel more secure and thus, less stressed.

It is slightly more difficult to see the connection between a conscientious owner and a stressed male dog, but it probably depends on the form that the trait takes. For example, a person who is more conscientious about their work may have less time to spend with the dog and therefore a weaker bond. Or, an owner who tries to be more conscientious about how they look after the dog may have more rules and be less flexible about allowing the dog to have freedom of choice in its life, which can be a factor in increased stress levels.

But there are assumptions and it is impossible to draw conclusions without a more detailed definition of “conscientiousness”.

Mr Newman, the 'world's saddest dog' became an internet sensation after being photographed outside a San Francisco cafe. Credit: Christopher Michel [CC BY 2.0]
Mr Newman, the 'world's saddest dog' became an internet sensation after being photographed outside a San Francisco cafe. Credit: Christopher Michel [CC BY 2.0]

Dog owners should take particular note of this study and consider how their own lifestyle and relationship with their dog may affect the mental well-being of both beings. Although there are still many questions to be answered about the relation between owner stress levels and dog stress levels, it is clear that they are not independent of each other. And so, if we are living particularly stressful lives, we may need to try to find ways to reduce the impact on our faithful canine companions.

Jan Hoole, lectures on Biology at Keele University, England.

This article first appeared on The Conversation.