I've had three cats in kidney failure and I hydrated all three cats. The vet taught me how to give the sub cutaneous fluids an all three cats did live longer than the vets expected. As for the food, I gave them whatever I could get them to eat; that was no easy chore. At times, when the cats refused to eat, I gave them wet food, either Hills A/D or Royal Caniin Recovery through a feeding syringe. After a couple of days of feeding this way, they would usually regain appetite and eat on their own,
Just this week I received an email from NewMax Health that was most interesting. Though this is for humans, I am going to ask my vet about this, for cats and dogs. Here is the link to this very cheap help for kidney failure:
Health, fitness and medical advice
Hope your kitty starts to eat and feels better.
Pam and Autry