Most renal dogs don't care for the prescription foods, or not for long anyway. If I could make a suggestion, look up and join the kidney diet group on yahoo. The moderators there are awesome and they can help you design a fresh food diet for your dog that is tasty, renal friendly, and meets nutritional requirements.
A rice and chicken mixture (cooked) is almost always okay to feed a dog, and is the least likely to upset his tummy. - Blu PS: you really do get what you pay for when it comes to pet food. I find it odd that your vet would recommend Purina, as normally you can only get the good, specialty foods at veterinarian's offices or high quality pet stores. Some good brands would be Science Diet, Iams, and Blue. I'm sure there are others out there, too. - Blu