My Scooter Bug throws up his food from time to time. He's done it his whole life and he's going to be 13 in September.

If he is on one food for too long, he starts throwing it up until I change it. Sometimes I get 3 months out of a food, sometimes a year. But as soon as he starts up-chucking it, I know to find a new kind.

Yep, as a result my kitties eat a lot of grocery store variety - I feed what he will tolerate, not what is the priciest.