
Raw is inappropriate for kidney problems as it contains a high precentage of phosphorus which is what you don't need for kidney issues. Look up the phosphorus content of dog foods and pick the lowest you can find, you do need a good quality food, so you may wish to consider adding things - breast of lamb or chicken legs (including the skin) - both cooked. They are fatty meats, with a low phosphorus content. Rice is also good and cottage cheese, boiled sweet potatoes (not baked). You can also add calcium - pure not in tablet form as that contains vit D which you need to avoid. Vit B, C and E are also useful as is whole fish oil. Avoid fish liver oil.
You should feed the calcium (yums indigestion tablets or well ground egg shells are useful) with one feed and the additional vitamins with the other. This is because calcium prevents the absorption of minerals and vitamins - you want it to soak up the phosphorus, but not to prevent the absorption of the vitamins you add. Vit D stops the calcium absorbing minerals & vitamins, which is why they add it to calcium tablets, but this will defeat the object for a kidney failure dog.
I had a GSD with kidney failure after an infection and one of the vets we saw was amazed that she was still living over a year later - said on the prescription diet I could have expected a couple of months. She was nearly 14 when I lost her. As she had a rice allergy it was more difficult for me - but eventually found a good food, if a puppy food, which was low in phosphorus, but can't remember what it was now. I added chicken or lamb or similar and she did very well on it.
Good luck with this.