There are several kidney diets out there. Hills make k/d. The regular k/d is YUCK, like a hockey puck, so it did not go over well at the house(I have 3 kidney cats). However, the k/d minced is what the crew is eating, I just mash it up with a fork and spoon before I let the cats eat it. I also use the Royal Cannin Renal 23 dry food. Eukanuka(sp)by Iams also has a kidney diet. All the ones mentioned are from the vet.
How old is Cosmo?? Will you also be giving sub q fluids? There are places that supply the fluids, IV lines, and needles at a far better price than from the vet. All you need is a 'script from the vet. I use a company here in NJ for over 4 years now, Brico. Here is a site that has TONS of info and I have found it the best one on the web!!! www.felinecrf.org It is run by an English woman that lost 2 cats to kidney disease. Good luck with Cosmo and please keep us posted!!!!