One in five Australian Shepherds will have a naturally bobbed tail, this according to the Australian Shepherd Health &
Genetics Institute and based on registration statistics from the time the trait was still listed on registration certificates.  The gene known to cause bob-tails in the breed has been located and found to be an incomplete dominant. This means that puppies who inherit two copies of the gene died early in utero (also known as being “absorbed”) which results in smaller litters. Pups with one copy are NBT (naturally bob tailed), but having this gene doesn’t determine tail length, or whether the tail is kinked or straight. That said, breeding two Aussies with a naturally bobbed tail is risky. Doing so can produce puppies with spina bifida or lower spinal cord defects.

In the United States the AKC breed standard states, “The Tail is straight, not to exceed four (4) inches, natural bobtail or docked.” The good news is that the Veterinary Genetics Laboratory at UC-Davis now offers a test for detecting the Natural Bobtail gene which breeders can use to identify dogs carrying this trait. Aussies born with longer tails are often docked a few days after birth to adhere to the breed standard, but as several countries have banned docking procedures, breeders, clubs, and even judges in those countries have to ask themselves: “What tail is correct?” As far as we’ve been able to determine, language specifying a particular tail conformation hasn’t been written prior to the bans on docking, so the answer would have to be that no one really knows. As the ASHGI points out, there is concern that different countries might decide on a “correct” Aussie tail that may be different from another country’s determination, and it “risks fragmenting the breed gene pool if tail types are deemed “correct” or “faulty” depending on the country in which the dog resides.”

Aussie owners and breeders may want to visit the ASHGI site as it’s a wealth of information.

“Happy Aussie” by Kris Hackleman is available in print here.