The Influence of Canine Ownership on Maternal and Fetal Microbiomes and Their Associated Health Outcomes: A Review of the Literature

Abstract

Abstract The human microbiome is the collection of microbes across both internal and external body sites that exist mutualistically with each person. There is a strong correlation between diverse microbial communities and improved health. Many factors influence microbial diversity including diet, exercise, medication use, and pet ownership. Canine ownership is touted as a direct and indirect means to combat modern overly hygienic conditions due to increased exposure to microbes in the outside environment. To examine this effect on maternal and fetal health, large-scale comparisons were made between various canine and human microbiomes. Microbes can be transferred from the mother’s gut, skin, oral, respiratory, vaginal, and placental microbiomes to her bloodstream and immune system. Here microbes are passed to the amniotic cavity where the fetus benefits from early exposure to these diverse microbes. Studies have consistently shown that canine ownership is linked to greater microbial diversity in both the mother and fetus. This includes beneficial microbes such as Lactobacillus species which decrease the risk of asthma and allergic reactions. It also confers benefits by decreasing the concentration of pathogenic or opportunistic microbes such as Ureaplasma, which is linked to preterm birth. The metabolites of these microbes also serve valuable roles, including short-chain fatty acids that provide a strengthened intestinal barrier and decreased HPA overactivity. This increased microbial diversity also correlates with enhanced immune system functioning as seen by decreased rates of allergic diseases, hypothalamic-pituitary-adrenal axis over-reactivity, inflammatory cytokines, and IgE-mediated reactions while enhancing NK cell function. This microbial diversity helps to prevent short-term negative outcomes including preterm birth and neonatal infections as well as long-term outcomes including cancer, diabetes, depression, dementia, gastrointestinal disease, and cardiovascular disease.