The Australian Cattle Dog (ACD), or simply Cattle Dog, is a breed of herding dog originally developed in Australia for droving cattle over long distances across rough terrain. The eyes are oval and dark, with an alert, keen expression. The neck and shoulders are strong and muscular; the forelegs are straight and parallel; and the feet round and arched, with small, sturdy toes and nails. Both red dogs and blue dogs are born white (except for any solid-coloured body or face markings) and the red or black hairs show from around 4-weeks of age as they grow and mature. Both red dogs and blue dogs are born white (except for any solid-coloured body or face markings) and the red or black hairs show from around 4-weeks of age as they grow and mature. The distinctive adult colouration is the result of black or red hairs closely interspersed through a predominantly white coat. Training, therefore, involves helping the dog adopt a lifestyle that is probably very different from that of its droving ancestors.