Its really hit or miss in alot of cases. We tried about 4 or 5 different types of food before we found one he wouldn't throw up, well in this case he only throws it up once in a blue moon. My father says the fella has hung in there out of pure meanness, which could very well be the case the cat is mean to almost everyone but me. He plays with me even though he's vicious, calls to me when I've been away for awhile and I come in, so we definitely have a special relationship goin on. He used to fetch when he was younger and my folks didn't have a dog, he would do backflips in the air catching these little rubber toys I threw for him. Then he'd hop back up on the footrest of the recliner and drop the toy ready to go again!