In November 2008, the American Veterinary M Assoc (AVMA) executive board made a decision to strengthen their stance opposing the cropping of ears and docking of tails as well as other surgeries performed on pets for purely cosmetic reasons. This decision was made amid a great deal of controversy, with the Utah Veterinary Medical Association (UVMA) even submitting a resolution to the House of Delegates of the AVMA asking for a more tolerant stance toward these surgical procedures.
The resolution, also supported by the AKC, was eventually voted down by the House of Delegates and a new position statement opposing cosmetic surgeries such as ear cropping and tail docking was adopted by the AVMA.
Puppies can and do die as a result of docking and that is why breeders are unlikely to dock a runt or undersize/weight puppy.
Show dogs - if there is a judge who is sympathetic to tailed dogs (unlikely as they are usually breders themselves) then undocked dogs stand a chance in the ring. It is also difficult to find a puppy conforming to a breed standard when not bred by those who show. However it is just as important to find a breeder who does not in-breed and has the inherited genetic health of the breed as their prime concern when mating.
Buyers should be looking out for eye testing having been done on sire and dam and also other problems see this link
Anti-Docking Alliance Web Site Puppies Pastoral&Toy Group