Having a dog as a pet might protect some babies from developing allergies and asthma later on. A study conducted with mice could explain why: Dust from homes with dogs includes a higher amount of beneficial bacteria. This helps establish a balanced immune system in a child that is less likely to attack harmless allergens.
“We wanted to see which organisms were protective,” said study co-author Susan Lynch, an associate professor of medicine at the University of California, San Francisco. She and her colleagues exposed young mice to both dust from a dog owner’s home as well as dust from a dog-free home. Then they exposed the mice to common allergens. The researchers found that mice exposed to dog dust were less likely to have allergic reactions and inflammation in their breathing passages (a sign of asthma) than those exposed to the regular dust. The results were published last week in the journal Proceedings of the National Academy of Sciences.
A particular bacteria in the dog dust — Lactobacillus johnsonii — was identified, and the researchers found that giving it to the mice protected them against respiratory virus infections, though not as well as the dog dust itself. Likely, other beneficial bacteria also exist in this dust, and Lynch said future studies will try to determine what those are.