Are the tags the type attached to the dog's ear? I can see this is a good idea (maybe I am being optomistic, but hopefully it will prevent bar owners getting a cute new puppy, only to turf it out when it's not so cute anymore) but here is an idea, to combat the problem of owners not being able to get to the sanctuary, would it not be possible for the sanctuary to visit a certain area each day to complete the process? Obviously this would cost money, but I am sure most responsible dog owners would be happy to pay a certain amount for this to happen. As long as the visits were publicised well, most owners would make a real effort to attend.