The role of dog keeping in the home microbiota and its impact on children's health

Abstract

Background: Children with dog contacts in early childhood are healthier and use less antibiotics during the first year of life. We have earlier identified dog-associated bacterial and fungal signals in house-dust microbiota. The aim of this study was to determine whether these signals in house dust mediate the dog keeping associated positive health effects in the first year of life. Methods: We studied 368 Finnish children from pregnancy and collected weekly diary data on otitis, fever, usage of antibiotics, and dog keeping from 9th to 52nd postnatal weeks. The dog-associated signals in house dust microbiota included the abundance of 12 bacterial and two fungal genera, which were determined alongside richness with Illumina MiSeq sequencing from floor dust samples collected at the child age of 2 months. Bacterial cell concentrations in floor dust were measured with quantitative PCR (qPCR). Generalized estimating equations (GEE) were used for statistical analyses of the microbe-health associations. Results: Eight of the dog-associated genera individually explained 10%–23% of the protective associations between dog keeping and at least one health outcome. The strongest effect was observed for the Pasteurella in relation to fever weeks. In addition, three correlated bacterial genera together explained 25% of the dog-associated reduction in antibiotic use. Bacterial or fungal richness, total cell concentrations, or proportion of human-sourced bacteria in house dust did not significantly mediate the dog-associated health effects. Conclusions: Specific dog-associated bacterial and fungal genera in house dust, but not richness, explained partly the associations between dog keeping and lower prevalence of respiratory infections.