Previous research has indicated that children who live in houses with dogs since birth are less vulnerable to allergies and asthma, but a new study has shed more light on why that is.

The study, published in the Proceedings of the National Academy of Sciences and even receiving coverage in the Wall Street Journal, used mice to test the hypothesis that dust from households with dogs somehow helps to protect children against allergies and asthma. 

During the study, researchers exposed some mice to dust from households where dogs lived, others to dust from homes with no dogs, and still others to no dust at all. They found that the mice that were exposed to dog dust were more resistant to airway inflammation caused by allergens and viral respiratory infection.

According to researchers, the dog dust helped to "reshape the community of microbes that live in the mouse gut - collectively known as the gastrointestinal microbiome - and also diminish immune system reactivity to common allergens."

Mice received the biggest health benefits from being exposed to dust from dogs that are allowed to live both inside and outside, researchers reported. As dogs roam around in both environments, they pick up a diverse range of microbes that ultimately have a more profound impact on the gastrointestinal microbiome.

Researchers also identified at least one bacterial species - Lactobacillus johnsonii - that prevented the airways of mice from becoming inflamed due to allergens or respiratory syncytial virus (RSV). Although Lactobacillus johnsonii produced preventive effects on its own, it still wasn't as potent as when mice were exposed to the full spectrum of microbes contained in dog dust, the study reported.

Opening the door for future therapies

Susan Lynch, Ph.D., one of the lead researchers and an associate professor with the Division of Gastroenterology at UC San Francisco, and her fellow researchers intend to follow up this study by looking more closely at specific bacterial species such as Lactobacillus johnsonii that could one day be used for therapeutic purposes.

"Gut microbiome manipulation represents a promising new therapeutic strategy to protect individuals against both pulmonary infection and allergic airway disease," Lynch said.