Pit bull is an umbrella term for several types of dog believed to have descended from bull and terriers. In the United States, the term is usually considered to include the American Pit Bull Terrier, American Staffordshire Terrier, American Bully, Staffordshire Bull Terrier, and sometimes the American Bulldog, along with any crossbred dog that shares certain physical characteristics with these breeds. In other countries, including the United Kingdom, the term is used as an abbreviation of the American Pit Bull Terrier breed specifically, while the Staffordshire Bull Terrier is not considered a pit bull. Most pit bull-type dogs descend from the British bull and terrier, a 19th-century dog-fighting type developed from crosses between the Old English Bulldog and the Old English Terrier.

The German Shepherd, also known in Britain as an Alsatian, is a German breed of working dog of medium to large size. The breed was developed by Max von Stephanitz using various traditional German herding dogs from 1899.