Quoting kitermom:" unfortunately a chip alone does little to no good for a stolen dog. Dogs can easily be taken into a vet ... [snip!] ... question the information being changed. Though I would like to look more into the gps thing someone mentioned previously. "
Quoting Squid Kid:" You can always get their ear tattooed. Or if you have the microchip serial number it doesn't matter if they change the info, you're tracking the dog by the identifier, not by the info on it."