I know a little about it, but the term "shutdown" that you are using is confusing. It would help to know what kind of kidney disease your kitty has and if it is chronic or acute. If by "shutdown" you mean approaching end stage kidney failure (which would be unlikely since he was on IV's), your cat is probably pretty nauseous, even if he has enough stamina to seem his old self in other ways. Also, you really need to keep him on the KD because it has the low protein that is essential for a kidney patient. Protein metabolism is very hard on the kidneys, and the KD will help his kidneys heal if his condition is acute, or prolong his life if it's chronic. If you can provide any more details maybe we can give you some of the information you need to help your little guy out.