Researchers both in North America and in Europe have long ago noted that allergies are much more likely to occur in children that live in households without pets (especially dogs).

Our western standards of hygiene have greatly decreased the quantity of germs and dust our immune system comes into contact with every day. As a result our immune system has lost the ability to distinguish normal things from dangerous things and starts mounting an allergic response to ordinary things like peanuts.

A new article published in Proceedings from the National Academy of Science has given some data to show why this is happening.   Dust was collected by the researcher from a house with a dog and a house without a dog and feed to young mice. These mice were then presented a common allergen. It turned out that the mice fed the dust coming from houses with dogs would not develop signs of allergy. Further study showed why- these mice had large quantities of a specific bacteria in the gut called Lactobacillus johnsonii and it protected the mice from developing allergies. It is too early to equate say that an identical mechanism happens in children, but it is likely.

The conclusion however is straightforward, pets especially dogs help prevent allergies in children and we are just now beginning to discover why this occurs.