The impact of dog-keeping on infant gut microbiota development
Prenatal and early-life dog exposure has been linked to reduced childhood atopy and asthma. A potential mechanism includes altered immune development in response to changes in the gut microbiome among dog-exposed infants. We sought to determine whether infants in homes with indoor dog(s) exhibit altered gut microbiome development. Pregnant women living in dog-keeping or pet-free homes were recruited. Infant stool samples were collected at intervals between 1 week and 18 months after birth.  Stool microbiome was assessed using 16S ribosomal sequencing. Perinatal maternal vaginal/rectal swabs and stool samples were sequenced in a subset of mothers. Stool microbial community trajectories were assessed with mixed effect, adjusted models comparing infants from dog-keeping versus pet-free homes.  Stool samples from dog-exposed infants were microbially richer (p=0.046) and more diverse (p=0.036) through age 18 months. Enhanced diversity was most apparent between 3 and 6 months of age. Across the collection period, dog exposure was associated with Fusobacterium depletion and Citrobacter genera enrichment, depletion of two Lactobacillus and one Citrobacter species, and enrichment of Dorea, Collinsella, Ruminococcus, Clostridaceae and two Lachnospiraceae sp. Statistically significant effects of dog exposure on ß-diversity metrics were restricted to formula-fed children.  Our findings indicate that prenatal/early-life dog exposure associates with an altered gut microbiome during infancy and supports a potential mechanism explaining lessened atopy and asthma.