Aug 26, 2026 | Dog Health

The Microbiome You Share With Your Dog: Why Living Together Changes Both of You

6 min read • 4 Citations

Key Insights: Dogs and their humans share more than a home. Studies show cohabiting families exchange elements of their microbiomes with each other and with their dogs in ways that measurably shape immunity, allergy risk, and long-term inflammatory load.

We grew up learning to think of bacteria as germs, the thing soap kills, the reason we sanitize counters. That framing isn't wrong, it's just incomplete.

 

A small subset of bacteria cause disease. The vast majority make up a living ecosystem that keeps our bodies (and our dogs' bodies) running. And when we share a home with a dog, our two ecosystems start to overlap in ways that show up in blood tests, immune function, and how our bodies age.

What The Microbiome Actually Is

Every animal, dogs and humans alike, hosts a resident population of microorganisms on the skin, in the mouth, and along the gut.

 

This community is the microbiome: producing vitamins the body cannot make on its own, crowding out disease-causing bacteria, and training the immune system.

 

The specific composition of a microbiome is shaped by genetics, age, diet, environment, and the other bodies that live in close proximity.

How A Dog Changes Your Microbiome

A 2013 study followed 60 households and compared the microbiomes of every person and every dog living in them (Song et al., 2013).

 

Parents shared skin microbiota with their children, spouses shared with each other, and adults in dog-owning households shared measurable microbial overlap with their dogs too.

 

Cohabiting humans and dogs share only a small percentage of microbial species outright. But that exchange nudges the diversity of the human microbiome upward, which turns out to be the more important variable.

 

Diversity matters because human microbiomes have been getting sparser. Cleaner homes, more processed diets, less outdoor contact. A microbiome with fewer species is less resilient and less capable of regulating immune activity. 

How You Change Your Dog's Microbiome

The exchange runs both ways. A 2021 study of wolves, dogs, and their humans found that skin microbiota shift measurably across all three when they share space (Wetzels et al., 2021). Dogs living with humans looked more like their humans, in terms of their microbiome, than like wild wolves.

 

For dogs, this cuts two ways. Diversity is good; it helps them tolerate a wider range of environments and organisms. But it also means the dog's microbiome is not just a product of their biology. It is a product of the diet you choose, the surfaces they lie on, the cleaning products in the home, and the outdoor time they get.

Why This Matters For Canine Longevity

The connection to aging is the least intuitive part of this story, and the most useful one.

 

Low microbial diversity in dogs correlates with markers of low-grade chronic inflammation. Chronic inflammation, in turn, is one of the main drivers of aging biology, a pattern known as inflammaging. A less diverse microbiome tends to allow more of the pro-inflammatory bacterial byproducts into circulation and produces fewer of the anti-inflammatory ones.

 

The practical version: a dog with a well-fed, well-diversified microbiome runs less inflammatory load through their body every day. Compound that across a decade of adult life and the difference in healthspan is meaningful.

What You Can Do Today

Practical moves that support a healthy shared microbiome, for both of you:

  • Vary the environment. Walks in different terrains (grass, dirt, forest, beach) expose your dog and, by extension, you to more microbial variety than repeat walks on the same concrete route.
  • Don't over-sanitize. Reasonable cleanliness is fine. Sterile is not the goal. Broad-spectrum antibacterial sprays used constantly on floors and surfaces suppress the exact diversity that keeps both microbiomes robust.
  • Feed for the gut. A varied, minimally-processed diet with adequate fiber supports microbial diversity in dogs. Kibble alone tends to reduce it. Adding fresh whole foods (steamed vegetables, some cooked meat, sardines a few times a week) helps.

Living with a dog reshapes your microbiome, and yours reshapes theirs. Most of that exchange is quietly good for both of you.

View Citations

Citations

1. Song, S.J., Lauber, C., Costello, E.K., et al. (2013). Cohabiting family members share microbiota with one another and with their dogs. eLife, 2, e00458. https://doi.org/10.7554/eLife.00458

 

2. Wetzels, S.U., Strachan, C.R., Conrady, B., et al. (2021). Wolves, dogs and humans in regular contact can mutually impact each other's skin microbiota. Scientific Reports, 11, 17106. https://doi.org/10.1038/s41598-021-96160-7

 

3. Misic, A.M., Davis, M.F., Tyldsley, A.S., et al. (2015). The shared microbiota of humans and companion animals as evaluated from Staphylococcus carriage sites. Microbiome, 3, 2. https://doi.org/10.1186/s40168-014-0052-7

 

4. Gao, X., Yin, M., Yang, P., et al. (2020). Effect of Exposure to Cats and Dogs on the Risk of Asthma and Allergic Rhinitis: A Systematic Review and Meta-analysis. American Journal of Rhinology & Allergy, 34(5), 703-714. https://doi.org/10.1177/1945892420932487