I have a 1 year old Great Dane who has gone through this. I first started him on a grain-free lamb Taste of the Wild formula and the same thing happened to him. In between his toes was always red, he had rashes, scratch at his ears constantly, had little bumps underneath his chin etc. I also fed him the Royal Cannin food, and I kept him on this for about 2 months. His symptoms improved tremendously but I couldn’t afford to pay 60 dollars a bag with a dog who eats so much food! My vet suggested that I try a novel protein-limited ingredient diet. I wasn’t sure what this meant at first, but it basically means all proteins that your dog has not been exposed to. So, Kangaroo, Duck, Bison, venison with just one other ingredient like rice or potatoes. I put Sully on grain-free Kangaroo and Duck formula but he just got worse. Surprisingly, I tried the food that your dog is on now (except for large breeds) his symptoms were completely gone! He’s been doing so much better and I’m so thankful because he was so miserable. What I would suggest doing is staying on the hydrolyzed (royal cannin) for about 2 months just to see if his symptoms go away, and if they do, then try out the limited ingredient novel proteins. Chewy.com has some great ones, they ship really fast too!

In my case, I think that Sully was allergic to some of the ingredients in the grain-free foods I had been feeding him (thank you to the kind individual on this message board who pointed this out to me), not necessarily the type of protein. However, I’ve read that a lot of dogs are more allergic to the most common proteins like chicken or beef, so that could be what you’re experiencing. So definitely stay on the hydrolyzed and then try out limited ingredient novel protein diets.