I have a friend who has a cat who had severe bladder stones. He is now rid of the stones and doing well. My question is, since I really don't have any experience with this (you'd think I would with 54 cats!), does she have to keep him on Science Diet CD or can she let him have the other premium foods that are designed for urinary tract health? Please don't tell me to ask my vet or her vet. All they say, is they don't know so feed the S.D. I thought maybe one of you have experienced this condition and would have more experience with the food issue. Thanks so much for your help.