Not cheap, but worth it
Lucy has always been very fussy about food, and would only eat a specific dry food. Then she stopped eating at all, and was sick every time she ate anything. After many expensive investigations, the vet diagnosed poly-cystic kidneys, and prescribed a renal diet. As my daughter's cat was also on a renal diet, I tried several foods before deciding which to buy. This is very much her favourite, and she now eats (or rather licks the gravy off) 2 pouches a day, plus a small handful of dry food.