By Dr. Becker
It seems all the lovely closeness we share with our canine companions – all the hugs, paw shakes, sloppy kisses, naps on the couch – populate our skin with microbes we wouldn’t be exposed to were it not for our furry friends.
A recent study conducted at the University of Colorado-Boulder1 shows that dog owners have “a more diverse and different set of skin bacteria” than non-dog owners, according to a Human Food Project article. The microbes in question are a blend of harmless bacteria from doggy tongues (Betaproteobacteria) and paws (actinobacteria).
If you find the prospect of these “diverse and different” bugs alarming, fear not. As it turns out, exposure to a variety of microbes has the potential to make you healthier by tuning up your immune system.
Do Family Members Share Microbes?
Identical twins are no more likely to have similar gut bacteria than fraternal twins, which has led scientists to conclude that genetics aren’t the only factor involved in determining what microbes we carry around on and in our bodies.
So the researchers at the University of Colorado-Boulder set out to discover how environment in the form of exposure to related and unrelated people and other species (dogs) affects the microbiota (microbe colonies) of humans.
Study participants included 159 people and 36 dogs, separated into four groups:
- Families with children aged 6 to 18
- Families with no children but one or more dogs
- Families with both children and dogs
- Families with no kids and no dogs
The researchers collected samples of skin (from the forehead, palms or paws, and tongues) and stool samples from all the participants (two- and four-legged) to determine what bacteria were present in each location.
Adult Dog Owners Share More Microbes with Their Dogs Than with Their Children
Analysis of the samples showed that human family members share similar microbes in the stool, on the skin, and in the mouth, with skin microbiota being the most similar. The researchers also found that parents share similar mouth and gut microbial communities with children aged 3 to 18, but less so with children under 3.
Other interesting findings:
- On average, 11 percent of bacteria on the hands is actually from oral sources, with less than 2 percent from fecal sources (thank goodness!).
- Couples with dogs share more palm and forehead microbes than non-dog owning couples, and dog owners also have “novel and rare” microbes on their skin.
- Adult dog owners share more microbes with their dogs than with their children.
- Adult females have a greater diversity of hand bacteria than adult males.
- Pet cats had no effect on the diversity of adult skin bacteria.
Interestingly, dog ownership seems to have no effect on oral or gut microbiota in humans.
Harmless Skin Bacteria Helps Train Your Immune System
The Colorado researchers noted that much of the common bacteria shared between humans and their dogs happens through licking. Another method of transmission occurs when dogs track bacteria in from outdoors and humans in the household pick it up. The paws and foreheads of dogs are a rich source of a great number of diverse microbes.
This study demonstrates that while the exposure of humans to the larger microbial world has shrunk in modern times, and not always to our benefit, dog owners may have an advantage thanks to the diverse microbial community they are exposed to through contact with fuzzy family members. Innocuous bacteria on your skin helps your immune system learn to distinguish between good and bad germs.