I microchip all my animals, dogs cats, birds and horses ( big and small) I do it myself excepot the horses since the placement is DEEP and I'd rather blame my vet if something goes wrong!
As I understand it, a slaughter house cannot kill a horse with a microchip unless the animal arrives with a signed letter stating it is OK to do so..............I do not know if this is the law in every state but have heard it is in the Northeast ( Canada too).
I also have YELLOW signs posted in the barn that all the animals are done, and on all my show crates for the dogs.
I buy my own (at $18.00 each, used to be $12.00) by the case, and register them all with Home Again ( the AKC) who takes all animals.