Few dogs are built as purely for speed as the Greyhound. This ancient sighthound type was refined in England to chase game by sight, and its deep chest, long legs and flexible back let it top 40 miles per hour. In the United States, most pet Greyhounds are retired racers placed by adoption groups, usually between two and five years old.
Off the track, many Greyhounds are calm. They sprint hard for a few minutes, then nap for much of the day, which earns them a reputation as gentle, quiet companions. Thin skin, a short coat and a lean frame mean they feel cold quickly and need soft bedding, while a strong chase instinct means many need careful introductions to cats and small dogs and should never run loose in unfenced areas.