THERE is a knock at the door. A uniformed official says he has come to take your dog. The dog has done nothing wrong, but his breed has been outlawed in the town where you live. You've had this dog since he was a puppy. He is obedience-trained, licensed and vaccinated. He never runs loose. He has never bitten anybody. And you love him. But it's bye-bye, Buffy, if he's the "wrong" breed. All over this country - and in Allegheny County - owners of pit bull terriers and rottweilers have been ordered to get rid of them or have...