The team conducted experiments with mice and found that exposing them to dust from homes where dogs live triggered changes in the community of microbes that live in the infant's gut and reduced immune system response to common allergens.
The scientists also identified a specific species of gut bacteria that's crucial in protecting the airways against allergens and viruses that cause respiratory infections, according to the study published online in the Proceedings of the National Academy of Sciences.
While these findings were made in mice, they're also likely to explain why children who are exposed to dogs from the time they're born are less likely to have allergies and asthma, the University of California, San Francisco (UCSF) and University of Michigan researchers said.
These results also suggest that changes in the gut bacteria community (gut microbiome) can affect immune function elsewhere in the body, said study co-leader Susan Lynch, an associate professor in the gastroenterology division at UCSF.
"The results of our study indicate that this is likely to be one mechanism through which the environment influences immune responses in early life," said Lynch in a UCSF news release. "It is something we are currently examining using human samples in a large multi-institutional collaborative study."
She said that it might be possible to use species of beneficial gut bacteria to remodel people's gut microbiomes to prevent the development of allergies or asthma, and even treat existing cases.
"Gut microbiome manipulation represents a promising new therapeutic strategy to protect individuals against both pulmonary infection and allergic airway disease," Lynch said.
Previously, the same research team found that dust in homes with a dog that was allowed inside and outside had more diverse types of bacteria and more species of bacteria that are found in people's gastrointestinal tracts.
This isn't to say that new parents should rush out to buy a dog. While the study found an association between the dogs and respiratory health in mice, it didn't establish a cause-and-effect relationship. And results of animal studies aren't always replicated in humans.
The American Academy of Allergy Asthma and Immunology has more about preventing allergies and asthma in children.