
It all depends on whether the breeder has had them docked by a vet or not. I would say the majority of them are docked.
The KC breed standard states : Tail - Customarily docked. Docked: Set on high and carried erect. Undocked: Set on high of moderate length to give an overall balanced appearance. Thick at the base and evenly tapering to tip, straight as possible and carried jauntily. An excessively gay or curled tail undesirable.