The Rottweiler (/ˈrɒtwaɪlər/, UK also /-vaɪlər/) is a breed of domestic dog, regarded as medium-to-large or large. The dogs were known in German as Rottweiler Metzgerhund, meaning Rottweil butchers' dogs, because their main use was to herd livestock and pull carts laden with butchered meat to market. This continued until the mid-19th century when railways replaced droving. The muzzle should appear neither elongated nor shortened in relation to the cranial region. The ratio between the length of the muzzle and the length of the skull is about 1 to 1.5. Rottweilers are a relatively healthy, disease-free breed. As with most large breeds, hip dysplasia can be a problem. For this reason the various Rottweiler breed clubs have had x-ray testing regimens in place for many years. Osteochondritis dissecans, a condition affecting the shoulder joints, can also be a problem due to the breed's rapid growth rate.