The Australian Cattle Dog, or simply Cattle Dog, is a breed of herding dog developed in Australia for droving cattle over long distances across rough terrain. This breed is a medium-sized, short-coated dog that occurs in two main colour forms. It has either red or black hair distributed fairly evenly through a white coat, which gives the appearance of a "red" or "blue" dog. As with dogs from other working breeds, the Australian Cattle Dog is energetic and intelligent with an independent streak. It responds well to structured training, particularly if it is interesting and challenging. It was originally bred to herd by biting, and is known to nip running children. It forms a strong attachment to its owners, and can be protective of them and their possessions. It is easy to groom and maintain, requiring little more than brushing during the shedding period. The most common health problems are deafness and progressive blindness (both hereditary conditions) and accidental injury. Thomas Simpson Hall, pastoralist and son of pioneer Hawkesbury region colonist George Hall, developed an Australian working dog for cattle farming during the mid 1800s. Robert Kaleski, who wrote the first standard for the cattle dog (later, the Australian cattle dog), called Hall's dogs "Halls Heelers". Thomas Hall imported dogs from the United Kingdom, in particular blue-speckled Highland Collies, and crossed them with selected dingoes to create the breed. The Halls Heelers were later developed, in particular by Jack and Harry Bagust from Sydney in the 1880s, into the two modern breeds, the Australian Cattle Dog and the Australian Stumpy Tail Cattle Dog. The Bagust brothers "bred a lot and drowned a lot" to create the breed.Australian Cattle Dog has been nicknamed a "Red Heeler" or "Blue Heeler" on the basis of its colouring and practice of moving reluctant cattle by nipping at their heels. The nickname "Queensland Heeler" may have originated in a popular booklet, published in Victoria.