Pit bull is a word used to describe several breeds of dog . This includes the American Pit Bull Terrier , American Staffordshire Terrier , and Staffordshire Bull Terrier , and dogs with a mix of these breeds . Most jurisdictions that restrict pit bulls , including Ontario , Canada , , Miami , Florida and Denver , Colorado , apply the restriction to the modern American pit bull terrier , American Staffordshire terrier , Staffordshire bull terrier , or any other dog that has the substantial physical characteristics and appearance of those breeds .