However, his fragile appearance is deceiving: At full gallop he is so incredibly fast (up to forty - five miles per hour) and has such strong chasing instincts that he must not be let off - leash except in a safe, enclosed area. (yourpurebredpuppy.com)
Greyhounds are known nippers and have a strong chase instinct, so they should be kept on leash and muzzle when out for a walk... or a run! (cuteness.com)
They can be aggressive towards other dogs and have strong chasing instincts, so if you happen to have a pet in your household, you should think twice prior to buying this breed. (puppiesdogs.org)