Scientists say teens who grow up with dogs may benefit from measurable improvements in mental health, and the reasons may go beyond companionship or reduced stress.
A Japanese research team led by Prof. Takefumi Kikusui found that adolescents with dogs showed significantly fewer social, behavioural, and emotional problems by age 14 compared with their peers. While past studies have linked dog ownership to stress reduction and higher oxytocin levels, this research points to another possible factor: differences in the microbiome.
The study analyzed 343 teens from the Tokyo Teenager Cohort, including 96 dog owners. Saliva samples revealed clear microbial distinctions, with 12 bacterial types, including Streptococcus and Prevotella, appearing far less often in teens without dogs.
To test how these microbes might affect behaviour, researchers transferred the teens' saliva bacteria into microbe-free mice. Mice given microbes from dog-owning teens displayed more social curiosity and behaviours resembling empathy. The team concluded that differences in microbiota may partly explain improved social behaviour in adolescents who live with dogs.
However, the study did not examine dogs' own microbes, leaving open whether the differences come from direct microbe transfer or from lower stress levels influencing teens' microbiomes. Experts caution that the mechanism remains unclear and note that owning a dog isn't universally positive, particularly when pets have behavioural issues.
Researchers emphasise that a healthy, diverse microbiome with or without a dog may still benefit mental health.
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