Pet Dogs Could Improve Children’s Health Through Household Microbes

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 who live with them?

A new study led by scientists at the Finnish Institute for Health and Welfare indicates that particular microbes found in household dust and associated with dogs could improve respiratory health outcomes for children during their first year.

Dog-associated microbes and infant respiratory health

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

When each child was two months old, researchers took dust samples from the living-room floor in every home, providing a measure of the bacteria and fungi to which the infants were exposed.

The findings appeared in Pediatric Allergy and Immunology.

There are many ways our canine friends benefit our health. (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.

As this research examined an existing setting and used statistical methods to identify data patterns, it cannot establish whether these factors have a causal effect. Even so, the results offer a promising direction for future 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 possible that we have also come to share some ‘good bugs’ with them.

Healthy dogs have a diverse range of microbes. (ChristopherBernard/iStock/Getty Images)

"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."

Asthma findings make the picture more complex

However, a separate observational study, published in May in the Journal of Allergy and Clinical Immunology: Global, suggests that the relationship may be more complicated.

That study analysed data from 99,389 children born in Sweden who were diagnosed with asthma and airway allergies between the ages of three and 16 years. Researchers statistically compared these records with 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 authors of that study reported.

At least at the population level, asthma outcomes did not appear to shift when children stopped being exposed to dogs.

This could indicate that dogs are not the decisive factor in asthma outcomes, although more research is required before any firm conclusion can be drawn.

Pets, ‘old friends’ and immune development

Another study, published in 2025 in Brain, Behavior and Immunity, found that growing up with pets may protect people living in urban environments from chronic low-grade inflammation.

One possible reason is that pets may increase exposure to what scientists call ‘old friends’ - microbes with which humans have co-evolved over millennia.

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."

Paediatrician Jenni Mäki, who took part in the Finnish research, says that the microbial environment in childhood is important to immune-system development, with dogs forming 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. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.