Although some Aussies are born with naturally bobbed or partially bobbed (stubby) tails, the majority are born with full, long tails. Breeders have historically docked the tails when the puppies are born. In the United States and Canada, the standard calls for a natural bob or docked tail not to exceed four inches as a defining characteristics. Any natural tail length is permitted when showing in Europe, where docking has been banned in most countries, including the United Kingdom. The term 'lethal white' originated from horses born with lethal white syndrome, and has since evolved to often describe dogs born with the double merle trait. This trait is found in many breeds, but most commonly found in Australian Shepherds. The name 'lethal white' is a misnomer, as this genetic condition is not lethal to the dogs; it is often the breeder who is lethal to the pups by culling them immediately after birth. Many consider the term 'lethal white' to be derogatory.