I had my dog chipped when she was spayed. Since she was under, the vet said he put it deep in the muscle. There is no way it can migrate out and no one would be able to find it without scanning. I've thought about chipping my horse - just haven't gotten around to talking with the vet about it. I think the chips are a great idea although I've teased that if the dog is bad, you can't "lose" it!!! Calm down! I'm just kidding ;-)