Tail docking isn't as simple as people say it is. It is an AMPUTATION. It is a slow and painful recovery for an animal. Just remember that. I am not against amputating a tail if its the only alternative but people often think tail amputation isn't a big deal. Anyways. I would just exercise her more to curb the high energy. My friend's lab was like this. Blood specks everywhere on the wall, knocking everything over that was at a human knee's height. It was terrible. They didn't amputate but they did exercise the dog a lot more and he wasn't wagging so intensely afterwards. Your dog probably needs at least 2 hours of structures exercise everyday to curb that energy.