Dogs aren't just man's best friend. Previous studies have shown that kids with dogs are less likely to develop asthma. Now a new study may show how—if results from mice apply to us. The work was presented at a meeting of the American Society for Microbiology. [Kei Fujimura et al., "Microbes in house dust from dog-owning homes protect against a common viral infection associated with increased risk of asthma development"]

The study tests what’s called the hygiene hypothesis. The idea is that extreme cleanliness may actually promote disease later on.

Researchers collected dust from homes that had a dog. They fed that house dust to mice. They then infected the mice with a common childhood infection called respiratory syncytial virus—or RSV. Mice who ate the dog dust were protected against RSV infection symptoms, like inflamed, mucus-coated airways, suggesting exposure helped them stave off the virus.

Those mice also had more diverse communities of gut bacteria than control mice did. The researchers say our pet's microbes may colonize our gut too, and help the immune system learn to respond to infections.

That's important because when kids develop severe RSV their risk of asthma goes up. So next time Buster sheds all over the couch, think of it as a bonus dose of probiotics.

—Christopher Intagliata

[The above text is a transcript of this podcast.]