Dog microbiota may protect children from respiratory tract infections: study

Children who have been in contact with dogs in early childhood are on average healthier and require fewer antibiotic courses than children without such contact, according to a recent study commissioned by the Finnish Institute for Health and Welfare (THL).

The protective association is explained, at least in part, by the spread of dog-associated microbes in the home, said THL in a press release on Friday.

In the study, the presence of specific dog-associated microbes in the home were linked to fewer respiratory tract infections, fewer antibiotic courses and more healthy weeks during the child’s first year of life.

The richness and diversity are higher in homes with a dog than in homes without a dog, but these general characteristics of the microbiota were not associated with the incidence of respiratory tract infections or morbidity in the child.

The study showed that certain dog-associated microbes or their combinations can explain up to one quarter of the protective effect of dog ownership on children’s respiratory tract infections, antibiotic use and the number of healthy weeks during the first year of life.

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

In addition to the dog’s microbiota, a more outdoor-oriented lifestyle in dog-owning families, shared responsibilities related to caring for the dog and partly similar dietary habits shared among dog owners may influence the microbiota in the home and among its inhabitants, and thereby the development of the child’s resistance to pathogens. These factors were not examined in this study.

“The results strengthen our understanding that the microbial environment during early childhood plays an important role in the development of child’s immune system. It has been suggested that in the future it may be possible to modify the home microbiota in ways that promote health,” said paediatrician Jenni Mäki.

“Respiratory tract infections in early childhood are a significant risk factor for asthma. 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,” said chief researcher Anne Karvonen.

The study included nearly 400 families from Finland. About one third of the families lived on farms, half in rural areas and the rest in towns.

The study was carried out by the THL, Kuopio University Hospital and the University of Eastern Finland.