Here is a case of an undocked Doberman, and the consequences. The dog is just over a year of age, and in the bottom photo, you can see the harness the owner has devised in an attempt to prevent injury due to tail wagging. She also shows the blood all over her house that she has to clean on a regular basis. It was interesting to hear that she received her tips from European members of Dobermantalk.com who are now experienced in tail injury care. You can see that in this Breed, as in most of the traditionally docked breeds, the tail is very long, whiplike, and unprotected by undercoat or fur.
Website depicting images described above http://s4.photobucket.com/albums/y150/hbwright/Jordan%20tail/