Our 20-year-old has CKD and we feed him a prescription food in the morning (Royal Canin Renal Support D) and a non-prescription food in the evening (Forza10 Renal Support paté).
Treats are limited to catnip, cat grass, and the very rare small piece of plain chicken.
What do you feed yours?
Royal Canin has some treats too. Our guy is diabetic and does the ultimino food and ultimino treats, I think there are renal support versions as well.