New research out of the University of California San Francisco is closing in on the reason living with dogs can prevent allergies.

Past studies have shown that living with dogs and cats early in life can save people from loads of allergy problems later, but scientists have never been sure why.

New research out of the University of California San Francisco is closing in on the possible reason for relief.

To date, the scientists have located a bacteria, called Lactobacillus johnsonii that seems to have a big impact on how test mice react to common allergens.

For the experiment, they separated mice into two groups.

Half of them got dust that had been gathered from a house where a dog lives and the others were showered with non-dog inhabitant particles.

All of the mice were then exposed to typical reaction-inducing substances including cockroach compounds and egg whites.

Lo and behold, the mice that were exposed to the dog-house dust were far less likely to experience inflammation and develop mucus.

Further examination revealed that the allergy-resistant mice had more of the L. johnsonii in their guts.

When the other mice were given doses of the bacteria, they, too, became better equipped to deal with allergens.

Making stronger direct links between the dogs and the bacteria is planned for the future.