Dog Owners' Home Bacterial Goldmines, Study Says

Does a dog live in your home? If so, chances are your house has more types of bacteria than homes without a dog, including some bacteria that are rarely found in households that do not have dogs, according to new research from North Carolina State University.

The study of bacteria in dog-owners' homes was part of a larger project to better understand the aspects of microbial life within a household.

"We wanted to know what variables influence the microbial ecosystems in our homes, and the biggest difference we've found so far is whether you own a dog," Rob Dunn, an associate professor of biology at NC State and co-author of a paper describing the work, said in a statement.

"We can tell whether you own a dog based on the bacteria we find on your television screen or pillow case. For example, there are bacteria normally found in soil that are 700 times more common in dog-owning households than in those without dogs."

Dunn, his colleagues and a group of "citizen scientists" used sterile swabs to collect biological samples from homes with and without dogs.

Nine prime pieces of bacterial real estate were tested: the TV screen, kitchen counter, refrigerator, toilet seat, cutting board, pillow case, exterior door handle, the trim around an interior door and the trim around an exterior door.

Each home was found to have its own unique community of bacteria, but of the 7,726 kinds of bacteria found throughout the homes, they could all be compartmentalized into three categories. The bacteria thrive on places we touch, places our food touches and places that collect dust. 

"We leave a microbial 'fingerprint' on everything we touch," Dunn said. "Sometimes those microbes come from our skin, sometimes they're oral bacteria and - as often as not - they're human fecal bacteria."

The wide range of microbes in the house is nothing be alarmed by, and it might even be helpful.

Women who have a dog in the home when pregnant, for instance, are less likely to have children with allergies, the researchers report. While it's merely a correlation - there is no causal link between the presence of a dog and the absence of allergies - it is believed that exposure to a wider variety of bacteria leads to greater resistance.

For comparison, the human body houses more than 10,000 species of bacteria and more than 100 trillion individual organisms, according to Discovery News.

While the data from the current study is from 40 homes, the researchers are in the midst of sampling a national survey of bacteria in 1,300 homes.

"The larger sample size will help us better understand the range of variables that influence these microbial ecosystems," Dunn says. "Does it matter if you have kids or live in an apartment? We expect the microbial populations of homes in deserts to be different from the populations of homes in Manhattan, but no one knows if that's true. We want to find out."

The research was published in the journal PLOS One.