Dirty dogs fill your home with bacteria


2013-05-23 14:51

Your beloved dog may bring your home a lot of joy, but it also fills it with a lot of bacteria, according to new research from North Carolina State University.

The research, published Wednesday in the journal PLoS ONE, found that homes with dogs living in them have an increased number of bacteria, as well as more different types of bacteria than homes without dogs.

The results were part of a larger study, which analyzed various kinds of microbes inhabiting 40 homes in the Raleigh-Durham area of North Carolina.

Residents participating in the study took samples from nine areas of their homes, and also reported various factors that might contribute to the proliferation of bacteria in their households, such as how many people lived there and whether they had any dogs or cats.

“The project was a first step toward making an atlas of microbes found in the entire home and how they may affect our health and well-being” said study co-author, Holly Menninger, director of public science at North Carolina State’s Your Wild Life program.

The areas of the home where the most dog-related bacteria was found were on pillowcases and television screens.

“Some of the microbes we know come from dogs themselves,” said Menninger. “Some of these bacteria come from the outdoor environment, such as dogs bringing bacteria from the soil and into homes.”

And some of the bacteria these dogs bring into the home can cause disease in humans like gingivitis and pneumonia, according to researchers who were able to identify a few different classes of disease-causing bacteria that came from dirty paws.

However, not all those dirty dog germs are necessarily bad. Even though researchers did not identify specific species of bacteria found in each home, they did report that most of the germs found were not disease-causing and may, in fact, have some positive benefits.

“We co-exist with bacteria and healthy, small exposures to bacteria do not pose any risk and might, on the other hand, be beneficial, as long as we keep a good hygienic environment,” said director of medical education at Miami Children's Hospital, Dr. Rani Gereige, who was not involved in the research.

According to one recent study, children exposed to a pet during their first year of life may boost their immune system and also lower their risk of developing allergies later on.

“Research has actually shown that mothers who live with dogs while pregnant are less likely to have children with conditions like atopic dermatitis or to develop allergies,” said veterinarian, Dr. Andy Roark, of Greenville, South Carolina.

Still, it’s important to be cautious when it comes to certain bacteria from dogs like salmonella and listeria, said Dr. Roark, as such germs can cause infections in humans.

“It is always a good idea for both adults and children to wash hands after playing with pets, especially before eating,” said Roark.

The bacteria found throughout the 40 different homes in the study fell into three general groups: 1) bacteria from skin and on surfaces we touch like door knobs and toilet seats; 2) bacteria from food in kitchens; and 3) bacteria in places where dust gathers like television screens and moldings.

Meanwhile, the researchers in this study are in the process of analyzing samples and other data from a total of 1,300 homes across the United States.

“We know we have all these bacteria in our home,” said Menninger. “Let’s learn to live with them.”

SOURCE: Home Life: Factors Structuring the Bacterial Diversity Found within and between Homes. PLoS ONE 8(5): e64133. doi:10.1371/journal.pone.0064133 (published May 22, 2013)