Research has long shown that children who grow up with family pets have a lower incidence of pet allergies and asthma, but a new study is closer to identifying the reason why. Researchers at the University of California San Francisco discovered that homes with dogs have higher levels of certain beneficial bacteria that help kids' developing immune systems be in balance and less likely to "overreact" to pet dander and other airborne allergens. More from Boston.com:
Previous research suggests that the establishment of certain gut bacteria in the intestinal tracts of newborns could affect their development of asthma later in childhood. Certain harmful bacteria associated with the use of antibiotics, for example, were found by European researchers to increase a child's risk of asthma, while living with a dog or cat in the house was found in other studies to decrease the risk.
"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 some 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 those 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 this week in the journal Proceedings of the National Academy of Sciences.
Researchers identified a particular bacteria in the dog dust—Lactobacillus johnsonii—and 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. "Lactobacillus could play an important role in structuring a healthy bacteria biome in the gut early in life," Lynch said, "but we have no actual evidence of that yet."
Image: Child and dog, via Shutterstock