The Greyhound can reach a full speed of 70 kilometres per hour (43 mph) within 30 metres (98 ft), or six strides from the boxes, traveling at almost 20 metres per second (66 ft/s) for the first 250 metres (820 ft) of a race. Greyhounds are typically a healthy and long-lived breed, and hereditary illness is rare. The Greyhound can reach a full speed of 70 kilometres per hour (43 mph) within 30 metres (98 ft), or six strides from the boxes, traveling at almost 20 metres per second (66 ft/s) for the first 250 metres (820 ft) of a race. Greyhounds are typically a healthy and long-lived breed, and hereditary illness is rare. Some Greyhounds have been known to develop esophageal achalasia, gastric dilatation volvulus (also known as bloat), and osteosarcoma. 'Double suspension rotary gallop' describes the fastest running gait of the Greyhound in which all four feet are free from the ground in two phases, contracted and extended, during each full stride.