I give my girls these, their teeth are much cleaner and their breath smells way better now! They have sensitive tummies, too, but these don't seem to bother them at all. A little expensive, but worth it, as I know that they're safe for them and well tolerated
Zuke's Z-Ridge Original Fresh Breath Dental Bone Mini 15pk
They also come in other flavors, carrot and cranberry. My girls seem to like the mint ones the best
This place is the cheapest I found too.