Aussie and MAS Tail Lengths
( just something simple )
NATURAL length tails in the Aussie and the Mini can be ANY length at all .... a nub, a half tail or a completely FULL tail. These breeds can even be born with an "absent" tail (no nub at all).
Most people can immediately recognize the tail-less silhouette of an Aussie, and once it starts swinging it's rump from side to side in a hula dancing fashion, there is no mistaking the breed. However, the "full tailed" Aussie and especially the MAS are both becoming increasingly popular.
A puppy born to parents who were both FULL-tailed at birth will also be FULL-tailed, so it is not hard to breed for FULL tails.
If one of the parent dogs has a "natural bob tail" ( NBT ) the puppy COULD also have a NBT ( in any length ) or be FULL tailed. Most NBT puppies have tails that are short enough to meet the breed standard and do not require docking. Other NBT puppies have 1/2 or 3/4 tails and look better docked shorter, which some breeders can't or won't do, so they shy away from the NBT dogs altogether.
Natural Bob Tails are identified at birth and should be noted. Some breeders have overlooked an ALMOST completely long tail as being a FULL tail or have failed to make note of the NBT and the dog (male or female) is later bred. Two NBT Aussies or MAS should not be bred to each other, so it is important to look closely at the tail and make note of the NBT puppy before the tail is docked (if it is docked).
The NBT gene mutation in the Aussie (and MAS) is a dominant gene and also, when doubled up on, is a "lethal" gene. A puppy that gets the NBT gene from both the mom and the dad ( two copies ) will die before being born ( resorption in utero ) . On rare instance it will survive with spinal cord defects. For these reasons only one parent should be a NBT when considering a mating.
Some people like tails and some people prefer the classic bob-tail look of the Aussie. The bob-tail can be achieved NATURALLY in the breed or can be docked to meet the conformation breed standard. Not all short tails have been docked. You may see propaganda that Aussie tails are either long (natural) or docked, but this is NOT true.
The correct terminology for a completely long-tailed Aussie / MAS is FULL TAILED ( or also "normal" tail because it didn't get the mutation that causes the bob-tail ).
Visit the internet for more in-depth articles on the Natural Bob Tail mutation.