How Owning a Dog Could Transform Your Children’s Mental Health, According to Research

While the mental health of adolescents increasingly worries families and professionals, a new study questions an unexpected lever: the presence of a dog in the home. Far from anecdotal discourse on the benefits of animals, researchers from Azabu University in Japan, in collaboration with several Japanese institutions, provide solid scientific data to support this hypothesis.

Published in the journal iScience, their study shows that adolescents who grow up with a dog have better behavioral and psychological indicators. These effects coincide with notable differences in their salivary microbiota, compared to that of their dog-free peers. This finding suggests that interactions with dogs could influence, in a biological way, the emotional and social development of young people. A surprising result, which opens a new avenue in the understanding of adolescent well-being.

Adolescents less at risk of behavioral disorders

The study carried out by the team of Professor Takefumi Kikusui, animal behavior researcher at Azabu University (Japan), highlights a significant correlation between the presence of a dog in the home and improved mental health in adolescents. Using data from the Tokyo Teenager Cohort Study, researchers followed 343 healthy young people aged 13, 96 of whom lived with a dog. The results, evaluated a year later, show clear differences. Adolescent dog owners score significantly lower on social withdrawal, aggression, delinquent behavior and thought disorders.

These findings are based on standard behavioral scales used in clinical studies to measure psychosocial problems. These scales make it possible to quantitatively assess symptoms such as isolation, emotional disorders or antisocial behavior. In this group, young people living with a dog showed better social adaptation and more stable interpersonal relationships.

This finding reinforces previous observations that associated dog ownership with positive effects on emotional well-being. However, this study goes further, by objectifying these effects via scientifically measured behavioral indicators. For the authors, it is not just an effect of companionship or affection. This is indeed a measurable phenomenon which could be based on biological mechanisms that are still poorly understood. This raises a new question. How can the presence of an animal influence the psychological development of an adolescent?

A microbial difference observed in adolescents with dogs

To understand the mechanisms underlying these effects, the researchers analyzed an element rarely studied in this context: saliva. Each adolescent participating in the study provided a saliva sample, allowing the microbial composition – or microbiota – present in their mouth to be examined. Contrary to what one might think, this microbiota is not intended to be trivial. It constitutes a biological interface with the environment and can influence various physiological processes, including those related to the brain.

The results showed that although the overall diversity of bacteria remained comparable between adolescent dog owners and non-owners, the bacterial composition differed markedly. Twelve types of bacteria were significantly less abundant in adolescents not living with a dog. These include genera such as Streptococcus and Prevotella, often associated with immune regulation and neuroimmune communication.

This variation does not appear to be trivial. Certain specific bacterial strains are known to produce metabolites that can influence the central nervous system, via the gut-brain axis. Indeed, bacteria in the mouth can mirror or interact with those in the digestive tract. An ecosystem known to play a role in the regulation of stress, emotions and cognition.

Professor Kikusui and his team hypothesize that this microbial difference could be partially linked to cohabitation with a dog. Either by direct transfer of microbes (licking, physical contact), or by indirect modulation via stress. In fact, dog owners report an increased feeling of security and calm. However, the study does not directly measure the canine microbiota. This leaves the question of the exact origin of these microbes still open.

An experiment on mice to test the behavioral impact of microbes

To test whether the microbial differences observed in adolescents' saliva had a causal impact on behavior, the researchers conducted an original laboratory experiment. They transplanted human salivary microbiota into axenic mice. In simpler terms, mice raised in a sterile environment, without any microorganisms. These animals are used in research to precisely isolate the effects of certain bacterial strains.

The team formed two groups of mice. One received salivary microbes from adolescents living with a dog, the other those from adolescents without a dog. The results revealed notable behavioral differences. Mice carrying the microbiota of young dog owners spent more time exploring new social interactions. In particular by sniffing their peers more and approaching more quickly a mouse trapped in a box. This latter behavior is interpreted as a form of empathic concern. A pro-social behavior studied in animal behavioral research.

According to the authors, these behaviors suggest that certain bacterial strains could influence personality traits such as empathy, social openness or reactivity to emotional signals. Of course, the researchers point out that human and mouse behaviors are not directly comparable. Nevertheless, these results support the idea that the microbiota can modulate social behaviors through biological mechanisms.

These data reinforce the hypothesis that cohabitation with a dog induces microbial changes in humans. And the latter could play an active role in the development of more positive social behaviors.

Towards a new understanding of the role of animals in mental health

One of the strengths of this study is to open a hitherto little explored avenue in understanding the link between pets and psychological well-being. She suggests that the beneficial effects of dogs on adolescents would not only be an emotional support or presence effect, but would be embodied biologically, via a measurable transformation of the human microbiota. This shift from the emotional to the biological changes the way we can think about the human-animal relationship.

However, the authors call for caution. On the one hand, they recognize that the exact source of the beneficial microbes is not yet identified. Are these bacteria transmitted directly by dogs, or indirect modifications linked to a reduction in stress in adolescents? On the other hand, the study does not allow us to conclude that there is a universal effect. Some dogs can represent a source of stress, particularly in the event of behavioral problems or poor care.

Professor Stefan Reber, from the University of Ulm in Germany, quoted by The Guardianwho did not participate in the study, also emphasizes that the results establish a correlation, not a definitive causality. This is a solid basis for future research, particularly on the interactions between microbiota, brain and social environment.

Finally, the researchers insist that the observed benefits could be obtained by other means. In particular through a varied diet, contact with nature, or other positive social interactions. It is therefore not a question of setting up the dog as a miracle solution. But perhaps to integrate this new variable into a more global approach to mental health in adolescence.

Source: Eiji Miyauchi et al., “Dog ownership during adolescence alters the microbiota and improves mental health“. Online now 113948 December 03, 2025