
I would be careful of both a BARF diet and a prescription one as mostly the former contains too much bone (phosphorus) and the latter insufficient protein. I had a GSD with kidney failure and I fed a home cooked diet as the prescription diets far too low in protein - additionally she was allergic to rice which at the time most kibble contained... but if you can feed rice it's a good base, I fed some sweet potato (boiled and water thrown away)... feed good quality protein but the diet should be low in phosphorus... not protein.
Chicken (with skin) legs, but no bones and breast of lamb are good, cottage cheese... it's also good to feed pure calcium (ground egg shells or the digestive tablets - Tums) NOT tablets of calcium (which include vit D). Calcium stops minerals & vitamins being absorbed (vit d prevents this) so feed calcium with the main meal and with a smaller meal feed vit E, B and whole fish oil. Don't feed fish liver oil.
My dog lived considerably longer than she would have done on the prescription diets available at the time.