Greyhounds are an ancient sighthound type, refined in England to chase game by sight. A deep chest, long legs and a flexible back carry them past 40 miles per hour. Most pet Greyhounds in the US are retired racers, usually two to five years old, so many know kennel life well but are new to stairs, glass doors and couches.
At home they're typically gentle and quiet, sprinting briefly and sleeping much of the day, though dogs vary. A short coat, thin skin and little body fat mean they chill easily and need soft bedding. A strong chase instinct means many need careful introductions to cats and small dogs. In San Diego, where parks and trails require a leash outside posted off-leash areas, that instinct is a good reason to keep a Greyhound on a lead everywhere except fenced spaces.