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?
I do that too with the Forza renal dry kibble, use it as treats. He also has a pill I have to give him every night so I do it right before his dinner so the paté is like a reward.