Pet Dogs May Improve Children's Health, But the Evidence Is Still Unclear

Dogs have been considered ‘part of the family’ for millennia, and families are known to share their microbes.

What, then, might this mean for the health of the people they live with?

A new study, led by scientists at the Finnish Institute for Health and Welfare, indicates that certain dog-derived microbes in household dust could improve respiratory health outcomes for children during their first year.

How dog-associated microbes were studied

The parents of 368 Finnish newborns recorded their infants’ ear infections, fever, and antibiotic use from the ninth week after birth until the children turned one. Families also stated whether they had a pet dog.

At two months old, each child’s home was visited for a living-room floor dust sample, allowing the researchers to assess the bacteria and fungi to which the infants were exposed.

The findings appeared in Pediatric Allergy and Immunology.

Our canine companions can support our health in many ways. (Catherine Falls Commercial/Moment/Getty Images)

"We show in this study that dog-associated bacterial and fungal genera or their combinations in house dust can explain up to one quarter of the associations between dog keeping and lower prevalence of respiratory infection during the first year of life," the authors report.

Because this was observational research, which documented existing circumstances and used statistical methods to identify patterns, it cannot establish that these effects are causal. Even so, the results offer a promising direction for further investigation.

We already know that beneficial microbes can be acquired from human family members. Given humanity’s long shared history with dogs, it is entirely plausible that we may also have come to share some ‘good bugs’ with them.

Healthy dogs carry a diverse array of microbes. (ChristopherBernard/iStock/Getty Images)

Dogs, respiratory infections and asthma risk

"Respiratory tract infections in early childhood are a significant risk factor for asthma," says chief researcher Anne Karvonen.

"When some of children's respiratory tract infections can be prevented with dog-associated microbes, this may also reduce the child's risk of developing asthma later in life."

Yet findings from a separate observational study, published in May in the Journal of Allergy and Clinical Immunology: Global, suggest that the relationship may be more complex.

That study examined data from 99,389 Swedish-born children diagnosed with asthma and airway allergies between the ages of three and 16. Researchers statistically compared these diagnoses against the children’s dog-ownership status over time.

"In children with established asthma and allergy, continuous dog exposure does not seem to increase the risk of moderate-to-severe asthma, but it is associated with a modest increased risk of exacerbations," the researchers behind that study reported.

At a population level, however, asthma outcomes appeared unchanged when children’s exposure to dogs stopped.

This could suggest that dogs themselves are not the decisive influence on asthma, although more research is needed before that can be determined with certainty.

Pets, ‘old friends’ and immune development

A further study, published in Brain, Behavior and Immunity in 2025, found that growing up with pets could protect people living in urban areas against chronic low-grade inflammation.

One possible explanation is that pets raise exposure to what researchers call ‘old friends’ - microbes with which humans have co-evolved over thousands of years.

Related: The Subtle Physical Clue That Could Indicate Your Dog Has Dementia

"Exposures to 'old friends,' which are thought to increase in homes with pets, interact with our immune system to produce more regulatory T cells," explained University of Colorado Boulder physiologist Christopher Lowry.

"Without sufficient exposure to 'old friends' we have reduced capacity to produce these regulatory T cells, which leads to inappropriate or unresolved inflammation."

Jenni Mäki, a paediatrician involved with the Finnish research, says that the microbial environment in childhood is important to immune-system development - and dogs form part of that environment.

"It has been suggested that in the future it may be possible to modify the home microbiota in ways that promote health," Mäki says.

"Our study shows that dog ownership already does this today."

This article was fact-checked by Rachel Garner and edited by Peter Dockrill. Although we take pride in our process, we are only human. If you notice an error, please let us know.