I thought I was doing my dogs a favor by paying more for Iams brand. My poor sheltie kept chewing at her paws and they were swollen and sore. Several trips to the vet, cortisone shots and meds didn't help. Finally, I switched to Hills Science Diet and her problem cleared up immediately! I now make sure that she gets food that doesn't list corn as the first ingredient. I still feed the Iams to my other dog with no problem, but the sheltie will be eating Hills from now on.