Our vet once said that for some strange reason, kidney cats seem to LOVE Mac Donald's french fries!! I brought some home once and WOW!!! did they go!!
Maybe it's all the salt? Have you ever seen the staff use the salt shaker on that thing? WOW! But that might make the cats drink more water, to flush it out of the system.

Bless little Mishi and all heart cats...I have one, and know there will be a day...

{{{{hugs}}}}