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. After Hall's death in 1870, the dogs became available beyond the Hall family and their associates. They were subsequently developed into two modern breeds: the Australian Cattle Dog and the Australian Stumpy Tail Cattle Dog. Robert Kaleski, who wrote the first standard for the breed, was influential in its development. Among the most popular activities for an Australian Cattle Dog is dog agility.