The Greyhound is a breed of dog, a sighthound which has been bred for coursing game and greyhound racing. Since the rise in large-scale adoption of retired racing Greyhounds, the breed has seen a resurgence in popularity as a family pet. It is also referred to as an English Greyhound. Due to the Greyhound's unique physiology and anatomy, a veterinarian who understands the issues relevant to the breed is generally needed when the dogs need treatment, particularly when anesthesia is required. Greyhounds cannot metabolize barbiturate-based anesthesia in the same way that other breeds can because their livers have lower amounts of oxidative enzymes.