I didn't know that either. I cruised over to The Cat Site and found some info. They also have maintenance diets which I believe that we tried with Syd.
Max did go back to eat twice now. He hasn't had a full meal but at least he is interested and eating willingly.
Max seems to be doing great. He did have some blood in his urine on Wednesday but he was still urinating...on the floor a few times but that's okay given the situation. He's eating and playing with Sydney again so I think that everything is working so far. Thanks for the well wishes.