Bulldog,  also known as the British Bulldog or English Bulldog, is a medium-sized dog breed. It is a muscular, hefty dog with a wrinkled face and a distinctive pushed-in nose. The Kennel Club (UK), the American Kennel Club (US), and the United Kennel Club (US) oversee breeding records. Bulldogs are popular pets; they were the fifth most popular purebreed in the US in 2017 according to the American Kennel Club. Bulldogs have characteristically wide heads and shoulders along with a pronounced mandibular prognathism. There are generally thick folds of skin on the brow; round, black, wide-set eyes; a short muzzle with characteristic folds called a rope or nose roll above the nose; hanging skin under the neck; drooping lips and pointed teeth, and an underbite with an upturned jaw. The coat is short, flat, and sleek with colours of red, fawn, white, brindle, and piebald.