The American Bulldog is a breed of working dog. The names associated with the Bully and Standard types are those of the breeders who were influential in developing them, John D. Johnson (Bully) and Alan Scott (Standard).

The American bulldog is a stocky, well built, strong-looking dog, with a large head and a muscular build. Its coat is short and generally smooth. The breed is a light to moderate shedder; however, they should be brushed on regular basis. Colors, while historically predominantly white with patches of red, black, or brindle, have grown in recent years to include many color patterns including black, red, brown, fawn, and all shades of brindle. The color conformation is quite varied, but solid black or any degree of merle is considered a cosmetic fault, and a blue color is a disqualification by the NKC Breed Standard. Black pigmentation on the nose and eye rims is preferred, with only some pink allowed. Eye color is usually brown, but heterochromia also occurs, although considered a cosmetic fault. American Bulldogs can be droolers; this varies and is more prevalent in the Bully type, which is generally a larger, heavier dog with a shorter muzzle. Standard or Performance types are generally more athletic with longer muzzles and a more square head. It is important to note that many modern American Bulldogs are a combination of the two types usually termed "hybrid." In general, American Bulldogs weigh between 27 to 54 kg (60 to 120 lb) and are 52 to 70 cm (20 to 28 in) at thewithers, but have been known to greatly exceed these dimensions, especially in the "out of standard," nonworking stock.

The original bulldog was preserved by working class immigrants who brought their working dogs with them to the American South. Small farmers and ranchers used this all-around working dog for many tasks including farm guardians, stock dogs and catch dog. These dogs were not an actual breed as considered by today's standards but were a generic bulldog type. There were no recorded pedigrees or records and breeding decisions were dependent on the best working farm dogs despite breed or background. Several separate strains of the "bulldog" type dogs were kept by ranchers as utilitarian working dogs.

Perhaps the most important role of the bulldog and the reason for its survival, and in fact why it thrived throughout the South, was because of the presence of feral pigs, introduced to the New World and without predators. The bulldogs were the settlers' only means of sufficiently dealing with the vermin. By World War II, the breed was near extinction until John D. Johnson and his father scoured the back roads of the South looking for the best specimens to revive the breed.

      During this time a young Alan Scott grew an interest in Johnson's dogs and began to work with him on the revitalization process. At some point, Alan Scott began infusing non-Johnson catch bulldogs from working Southern farms with John D. Johnson's line, creating the now Standard American Bulldog. At another point, Johnson began crossing his line with an atavistic English bulldog from the North that had maintained its genetic athletic vigor. American bulldogs are now safe from extinction and are enjoying a healthy increase in popularity, either as a working/protector dog or as a family pet. All over the world, they are used variously as "hog dogs" (catching escaped pigs or hunting razorbacks), as cattle drovers and as working or sport K-9s. American Bulldogs also successfully compete in several dog sports such as dog obedience, Schutzhund, French Ring, Mondio Ring, Iron Dog competition and weight pulling. They are also exhibited in conformation shows in the UKC, NKC, ABA, ABRA and the SACBR (South Africa).