We have a foster with severe allergies, and we were told that the most common dog food allergies are chicken, beef, corn, wheat, etc. Our vet recommends Natural Balance Duck and Potato food. We had a no kill los angeles rescue last year allergic to tap water, and only could drink filtered (I still don't quite understand that one) and a dog last year that was allergic to grass, and we had to wash her feet every time we came in. Its a lot of trial and error. Its expensive, but you can always contact a dog dermatologist to do skin tests. I think for us, it was going to be about $500. Good luck!View Thread