In a new study in the Proceedings of the National Academy of Sciences, mice exposed to dust from homes with dogs were protected against allergens known to trigger asthma. This dog-associated dust enriches the variety of gut bacteria in the mice with Lactobacillus johnsonii, a type of bacteria that protects the airway against allergens and infection by beefing up mucous membrane immunity. Not to worry, cat lovers. Although this study focused on dogs, having cats around early in life could help you stand up to allergies and asthma, too.  “In our previous research, we demonstrated that homes with indoor/outdoor cats also exhibited a more diverse house dust microbiome,” says study author Susan Lynch, PhD, associate professor of medicine at the University of California in San Francisco. If you want to get the immunity benefits without a furry friend, you’ll have to wait. The protective microbes needed to ward off allergies are only available via pet exposure at the moment, Dr. Lynch says. “Our aim moving forward is to build upon these studies and develop probiotic therapies for allergic asthma.”  More from Prevention: 7 Reasons You Need A Dog