There are different opinions on what breeds have been used as 'ingredients' in this american breed, but boxer, english bulldog and staffordshire bull terrier, or perhaps american pit bull terrier have been mentioned. The breed has also been called 'old bulldog' and does resemble the bulldogs as depicted in paintings during the 1800s, which were leggier and lighter, with longer muzzles, than today's english bulldog.
The most well-known american bulldog is probably the dog that played 'Chase' in the movie Homeward Bound.
Today, the breed is divided into two main strains, Classic (Johnson, Bully) and Standard (Scott, Performance).

Both types of american bulldog should be athletic, strong, agile and with great endurance. Ears and tail may be cropped/docked, but natural is preferred. The coat can be a variety of colours, but solid black, blue or one of these with tan markings, is not allowed. The standard points out, however, that a dog may appear to be black when it is really, for instance, brindle or fawn with a lot of white and just a bit of what appears to be solid black showing.