Let them eat dirt! And a few worm eggs, too!
I found this interesting article in the New York Times today Babies Know: A Little Dirt Is Good for You. While lately we have been hearing about how a little dirt and animal hair is actually good for us, this article goes one step further in explaining that intestine worms may also be good for our immune systems.
In fact they have found that some intestinal worms actually help people (should be the same for our animal friends) with autoimmune diseases such as asthma, allergies, or even some of the more severe ones like MS, diabetes, and inflammatory bowel disease. It makes me wonder if some of the rise in autoimmune illness in animals is linked to the routine deworming some of our animals receive. I hope they do more research on this subject!