Move over man, dogs have a new best friend.

Or perhaps more accurately, dogs are even more of our friend now that we know the positive health effects that a pet dog can have on our microbiome!

Our gut microbiome can be affected by more than just what we eat. Our environment can and does alter our microbiome, even deep in our gut, and more obviously on our skin. The interactions between a dog (or cat!) that lives in our home and our microbiome have been repeatedly demonstrated to have positive effects as related to allergies, asthma, atopic disease, and metabolic disease. Wow! The benefit of these effects is more effective at a younger age, so theoretically, growing up with pets is better for you than owning pets only as an adult. However, both are great!

A study done with 746 infants showed that the presence of a dog or cat significantly increased the infant’s gut species richness in the phylum Firmicutes, composed of families like the Clostridiaceae, Lachnospiraceae and Ruminococcaceae. This is important because these correlate with a very healthy infant gut, and a shortage of these are connected with malnutrition. Other results showed that infants with pets had favorable Ruminococcus or Oscillospira populations, which are associated with leanness, reducing allergens, reducing the risk of pediatric inflammatory bowel disease, and preventing pathogens.

A more general theory that may explain the connection between pets and better health is the hygiene hypothesis.  Many advancements and revisions have been made since this theory was introduced in the 1990’s, but the basic premise is that when we are exposed to more microbes- bacteria, dander, etc- as an infant and child, our body is better trained on how to handle them as we age. Broadly speaking, a lack of exposure (training) can lead to overreactions by the immune system later in life. 

Quick note about other pets: Adults with rodents and reptiles as pets showed a higher level of akkermansia muciniphila present in their gut. This bacteria is considered a very beneficial bacteria, known to prevent pathogens, improve the condition of the gut lining, and a shortage of this is connected to obesity and irritable bowel syndrome. Score one for the pet-tank industry!

Does this mean we end up with bacteria from dogs? Ew!

Having an animal in the home means there is greater microbial diversity. Yes, some of their bacteria ends up in and on you. We don’t eat their poo- please!- but we do live in community with our pets and our tiny microbes have ways of transporting themselves to new hosts. The type of floor in your home, the size of your home, the number of people in your household, and more can affect the microbial transfers between beings. General cleanliness is always recommended, but the unavoidable transmission of microbes is natural and sometimes even beneficial! (*Googles local animal shelter adoption sites*)

TLDR: Growing up with a pet in your home has been connected to having a greater microbial diversity in your gut. This improved diversity can help prevent or lessen allergies, asthma, and other health concerns!

Sources and other helpful info:

Kates, A. E., Jarrett, O., Skarlupka, J. H., Sethi, A., Duster, M., Watson, L., Suen, G., Poulsen, K., & Safdar, N. (2020). Household Pet Ownership and the Microbial Diversity of the Human Gut Microbiota. Frontiers in cellular and infection microbiology, 10, 73.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7058978/pdf/fcimb-10-00073.pdf

Tun, H.M., Konya, T., Takaro, T.K. et al. (2017, April 6). Exposure to household furry pets influences the gut microbiota of infants at 3–4 months following various birth scenarios. Microbiome 5, 40.
https://microbiomejournal.biomedcentral.com/track/pdf/10.1186/s40168-017-0254-x.pdf