Soon after we got Taggert, he started doing that too. However when we changed his food, he stopped. He is on Sensible Choice, Lamb and Rice. But if you have tried changing foods, and things have not changed, I am not sure. Do your dogs chew a lot of rawhide? We have had problems with some rawhide but of course not to that extent. How about treats?

I think Amy's advice is about the best. Although you might check to see if the ingredients basically the same in all of them and then change one with a totally different base. (Now I am going to show my stupidity - I think there are some non-meat based ones out there).