If you are always stressed, your dog might catch it too, says study
Dogs mirror the stress levels of their owners, says a new study, which reveals that humans who experience long-term stress, can pass it onto their dogs.
The study is the first demonstration of a long-term synchronization in stress levels between members of two different species. Long-term stress contagion has previously been shown between human mothers and both their infants and their older children, says the paper, 'Long-term stress levels are synchronized in dogs and their owners', which was published in Scientific Reports.
"We have found that dogs and their owners synchronize in long-term stress, measured at two different occasions, reflecting levels during previous summer and winter months. Dog parents should not be worried, though. The findings confirm what most dog owners already know, which is what a strong bond we have with our dogs," Lina Roth, a research fellow at Linköping University, Sweden, and one of the authors of the study, told MEA WorldWide (MEAWW).
Studies have earlier shown that short-term anxiety is contagious between owners and their dogs, especially if they are participating in a mutual or interactive physical activity (such as a competition or police work), but that does not necessarily reflect the contagious effects of psychological stress, says the research team.
To evaluate the stress levels of both humans and their dogs, the research team studied 58 dog-human dyads and analyzed the concentrations of the stress hormone cortisol in hair and fur, to evaluate the changes in their stress levels.
Hair samples were obtained from both owners and their dogs at two separate occasions (September/October 2017 and February 2018).
The dog hair was cut from the neck as close to the skin as possible, and the human hair was cut off close to the scalp. The dog owners were asked to complete surveys about both their dog's personality and their personality.
Further, the dogs’ activity levels were continuously monitored with a remote cloud-based activity collar for one week. According to the paper, "Personalities of the dogs and owners were assessed through owner-completed dog personality questionnaire. In addition, information on daily routines with the dog, housing, training amount, and competing frequency was collected. The dogs were defined as competing dogs if they actively trained and competed in agility or/and obedience; otherwise, they were classified as pet dogs. A dog-owner dyad always shared a certain lifestyle, that is, competing or pet lifestyle."
Results showed that if an owner had high amounts of cortisol in their hair, their dog too had high amounts of cortisol. Interestingly, the study found that an anxious dog did not have the same impact on their human.
"We find it really interesting that the owner's personality affects the dog's long-term stress, while the dogs own personality revealed little effect," Roth told MEAWW.
The researchers say in the paper that they have demonstrated that the owner's personality rather than the dog's personality affects hair cortisol concentration, and therefore suggest that dogs mirror the stress of their owners.
“Although dogs’ personalities had little effects on their hair cortisol concentrations, the human personality traits - neuroticism, conscientiousness, and openness - significantly affected dog hair cortisol concentrations. Hence, we suggest that dogs, to a great extent, mirror the stress level of their owners,” says the paper.
Roth says while the present study provided no evidence that a dog's personality/emotions could have a similar impact on their human parent, further investigations may be required in that direction.
"We could not find that in our study, but there are, of course, more aspects that now has to be considered in future studies. We do not know the mechanism behind these correlations, but we do find that competing dogs, for example, show a stronger correlation than pet dogs. This makes us speculate that it could be the interaction and the training between competing dogs and their owners that increases the emotional closeness and generates stronger long-term stress synchronization. Further studies are, however, needed before we can draw any conclusions about the cause of the correlations," says Roth.