Homes with dogs have very different microscopic life forms than those without, new research finds.

The study, published in PLoS ONE, determined bacteria in homes with dogs is more prevalent, and includes types that are rarely found in residences without dogs.

“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,” co-author Rob Dunn, an associate professor of biology at North Carolina State, said in a press release.

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

For the study, Dunn and his colleagues used sterile swabs to collect organisms from homes with and without dogs. The researchers took the samples from nine surfaces: 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.

The scientists found 7,726 different types of bacteria. Most of these organisms were found in places we touch, where our food touches, and that collect dust.

“We leave a microbial ‘fingerprint’ on everything we touch,” Dunn explained. “Sometimes those microbes come from our skin, sometimes they’re oral bacteria and — as often as not — they’re human fecal bacteria.”

The human body houses over 10,000 species of bacteria and more than 100 trillion individual organisms.

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Bacteria would seem to be the last thing we’d need, but that’s not the case. This phenomenon, however gross sounding, seems to be healthy for most people.

Women who have a dog in the home when pregnant, for example, are less likely to have children with allergies. Researchers suspect the mom-to-be and her unborn child are exposed to a wider variety of microbes. They then become accustomed to them.

The researchers took samples from a national survey of 1,300 homes across the United States and are in the process of analyzing those.

“Does it matter if you have kids or live in an apartment?” Dunn said. “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.”

(Image: Serge Melki, Flickr)