Smudge is a longhair, and upchucks the occasional hairball, but since the vet suggested adding a bit of fiber to his canned "treat food" he has them less often, and they're smaller. I think some of the ingested hair is being passed through. He's certainly a lot more comfortable in the litterbox, anyway (he used to be constipated all the time). I think the only kind of drugstore fiber supplement that's been proven safe in cats is psyllium (which is the usual generic fiber stuff) but some cats enjoy a bit of canned pumpkin mixed into their food. A few like it just plain!