I've only fed Finn one or two of them...I thought they were made of more natural ingredients than some of the other things you can give...hmph. I know they're a lot less nasty than rawhide, as far as what it does when it gets moist and what it does to carpets (seems like it'd do the same thing to the inside of a dog, too!). I guess I probably will do a lot more research on what the greenies are actually made of before I give Finn another one. I wouldn't buy them anyway, they're too pricey. The only time Finn's had any was when they were freebies.