conformation
Many Australian Cattle Dogs have a stripe of white hair in the center of the forehead, usually 1/2 inch to 1 inch by 2 inches to 3 inches (about 2 cm by 7 cm) called the Bentley Mark. This is similar in appearance to the blaze markings sometimes found on horses. According to legend, a popular dog owned by Tom Bentley passed on this distinctive mark to all Australian Cattle Dogs.
A female Australian Cattle Dog should measure about 17 to 19 inches (43 to 48 cm) at the withers. A male Australian Cattle Dog should measure about 18 to 20 inches (46 to 51 cm) at the withers. An ACD is a well-muscled, compact dog with a short, dense coat and a naturally long tail. An ACD in good condition should weigh roughly 40 to 50 pounds (18 to 23 kg).
Some breeders dock ACD’s tails. This is a controversial practice and, in some countries, is illegal or is prohibited for show dogs. Docking Australian Cattle Dogs’ tails is a practice peculiar to the United States - ACD tails are not docked in their country of origin, Australia. However, the ACD absolutely needs its attractive tail for balance and steering while working or in agility. It is widely believed the tails are docked because of the mistaken notion that the dog will get its tail caught in doors or mouths of irate livestock. This is not to be confused with the Stumpy-tailed Cattle Dog, which is born with a naturally docked, or ‘bobbed’ tail; this animal strongly resembles the ACD in colouring, but has a slightly taller, leaner conformation.
Source: Wikipedia under the terms of the GNU Free Documentation License