Dog Microbes May Protect Against Childhood Infections

Many families enjoy the companionship that pet dogs provide, but could they also help protect children from infections?

Respiratory tract infections are among the most common illnesses in infancy and a leading reason for antibiotic prescribing in young children. These infections in early childhood are also a recognized risk factor for asthma.

A study by researchers at the Finnish Institute for Health and Welfare, Kuopio University Hospital, and the University of Eastern Finland found that children exposed to dog-associated microbes experienced fewer respiratory tract infections, more healthy weeks during their first year of life, and fewer courses of antibiotics.

Dog-associated microbes linked to better health

The team followed 368 Finnish children from pregnancy through to 1 year of age and collected weekly diary data on otitis (inflammation or infection of the ear), fever, antibiotic use, and dog keeping. The researchers assessed the household microbiome using floor dust samples collected when children were two months old. The children were participants in Finland's LUKAS birth cohort study, with around one-third of participants living on farms, roughly half in rural areas, and the remainder in urban settings.

Dr. Jenni Mäki, a pediatrician at Kuopio University Hospital and one of the study authors, explained that dog-associated microbes may be one of the mechanisms underlying the health benefits of dog exposure: “The principal finding of the present study was that individual dog-associated microbes accounted for 10%–23% of the protective effect of dog exposure on respiratory tract infections in young children. Moreover, a combination of three microbial genera explained up to one quarter of this effect.”

The strongest association was observed for Pasteurella, particularly in relation to fewer weeks with fever. Pasteurella species are gram-negative coccobacilli that colonize the oral cavity of dogs and cats but typically are not present in the normal microbial flora of humans.

While cats also carry Pasteurella species, dogs may have a stronger influence on the home microbiome, as cats are commonly indoor-only pets and dogs regularly move between indoor and outdoor environments.

The findings align with the biodiversity hypothesis, which proposes that exposure to a wider range of environmental microbes enriches the human microbiome and protects from allergy and inflammatory disorders. Mäki suggested that exposure to dog-associated microbes may shape the development of a child’s immune response.

The team previously found that having a dog increases the richness of the household bacterial microbiota. Mäki explained that while greater microbial richness and diversity in the home environment have been associated with protection against conditions such as allergies and asthma, “In the present study, bacterial richness was not associated with respiratory tract infections in young children and therefore could not explain the protective effect of dog exposure.”

The protective effect of dog ownership remained even after accounting for factors known to influence childhood infection risk, including family size, living environment, and exposure to tobacco smoke.

The questionnaires used in the study did not cover outdoor activity, so it’s unclear whether the lifestyle factors associated with dog ownership contribute to the benefits observed. “We were unable to assess or compare the effects of the child’s and parent’s outdoor activities on the child’s health. However, we do believe that outdoor activities in nature support health. Therefore, we encourage all families with young children and pregnant women to engage in outdoor activities in parks, forests, and other natural settings, including waterside environments,” Mäki said.

Because the study was observational, the findings cannot prove that dog-associated microbes directly prevent infections. Other factors associated with dog ownership may also contribute to the observed health benefits.

Previous studies have shown that microbial levels in homes on farms are substantially higher than those in urban homes. In the present study, all analyses were adjusted for residential environment (farm, rural, or suburban setting), but the team did not conduct separate analyses for these groups. As a result, it remains unclear whether the association between dog-associated microbes and children’s health differed across these environments.

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Mäki suggested that spending time in nature and near natural bodies of water may be beneficial to the immune system. “If spending time in nature is not possible, it may be possible to modify the home microbiome by, for example, bringing forest soil indoors, which has been tested in one small pilot study,” she said.

“If the goal is to modify the home microbiota to support health or even prevent diseases, it is important to know which microbes are present rather than simply whether microbial diversity or richness is high,” Mäki said.

The findings contribute to a growing body of research suggesting that specific environmental microbes may play a role in shaping immune development. Future studies may help identify which microbes offer the greatest benefits and whether those effects can be replicated without pet ownership.

“Perhaps in the future, we will see a product containing dog-associated microbes that can be sprayed onto surfaces in the home,” Mäki concluded.

Reference: Mäki JM, Kirjavainen PV, Täubel M, et al. The role of dog keeping in the home microbiota and its impact on children’s health. Pediatr Allergy Immunol. 2026;37(6):e70408. doi: 10.1111/pai.70408

About the interviewee:

Dr. Jenni Mäki is a specialist in Pediatrics at Kuopio University Hospital and the Finnish Institute for Health and Welfare.