The Rottweiler (/ˈrɒtwaɪlər/, UK also /-vaɪlər/) is a breed of domestic dog, regarded as medium-to-large or large. This continued until the mid-19th century when railways replaced droving. Although still used to herd stock in many parts of the world, Rottweilers are now also used as search and rescue dogs, as guard dogs, and as police dogs. The buildup to World War I saw a great demand for police dogs, which led to a revival of interest in the Rottweiler. During the First and Second World Wars, Rottweilers saw service in various roles, including as messenger, ambulance, draught, and guard dogs. The DRK counted around 500 Rottweilers, and the SDRK 3000 Rottweilers. The goals of the two clubs were different. The DRK aimed to produce working dogs and did not emphasise the morphology of the Rottweiler. The eyes should be of medium size, almond-shaped and dark brown in colour. The eyes should be of medium size, almond-shaped and dark brown in colour.