Here's my experience with a bald docked tail. I got Chipper when he was 4 mo. old. Went to have his check-up according to the agreement I signed. Asked the docs why the tail was bald. No idea. They said that's the way it would be. I'm kind of shocked so I go back to the breeder. Duh, Chipper's tail had been shaved before the docking.
Now it has thick, thick hair on it. Needless to say I did not go back to that vet. Joanne