Greyhound is considered the fastest dog breeds in running up to 800 meters (2,600 feet) and possibly longer distances. In 1996 the Guinness Book of World Records listed greyhound as the fastest dog, capable of reaching a speed of 68.8 km/h (42.8 mph).description:Greyhound is a visual dog - that is, based on the sense of sight in tracking and chasing prey instead of the sense of the sun - about 23-28 inches (58-71 cm) long from foot to stranger and weighing 35-65 pounds (16-29 kg). Female greyhound is smaller in size than male. His neck is long, skinny, he has big eyes, long ears, wide ears, long tail and curved.