Wow!! What a thread. At the humane society where I work we tatto. This is done the same time the animal is under to be spayed or neutered. Therefore, it doesn't feel a thing. We are non-profit and this (for rght now) is the best way for us to identify the animals in case they get lost or whatever. From what I understand there is more than one type of chip so more than one type of scanner is needed. Not always practical. I have been able to return dogs to owners due to our tatto. I have had people call and say they have found a dog with our tattoo and no tags. We enter the tat# in the computer and there ya go the owner! I also believe in tags, because your neighbor down the street is going to look for tags(for sure), maybe a tattoo, but won't beable to scan for a chip.