Thanks, all. You've helped me feel less worried, though I'm still concerned. I hope he's able to pass it, and that it doesn't hurt too much on the way out! The plastic was thin but had a lot of corners--eek.

He's been particularly bad about eating off the ground the past two days--I think it's because I've been feeding him super bland food because of his gastroenteritis (which was caused, most likely, by something he ate off of the ground). It's basically rice held together with a little turkey. I don't think it's very filling.