Two snags re "chip" implants, one they can be read by someone with a small "reader" and
you would never know until your identity is used by someone else.
Two, dogs that have had implanted chips are much more prone to developing cancer, I read
this in an article written by some vet in the U.S. a few months ago.
http://www.rense.com/general78/cancer.htm
http://www.rense.com/general82/drr.htm