The RX foods are great if you have a pup in renal failure. I have found that pups tend to not like Hill's KD so much....I use Purina NF instead. I currently have two on it and they are doing very well.
Don't let the hoopla about ingredients prevent you from using these foods. The RX foods are excellent and can save lives....at least extend them. I have used them for years.
Of course, you can always do a consult with a veterinary nutritionist and home cook.
American College of Veterinary Nutrition | ACVN