The American Bulldog is a breed of working dog developed for catching livestock and for protecting property. Though larger in size, they are the closest surviving relative of the Old English Bulldog because they were not altered to as great an extent while in Colonial America as their European cousins. There are generally considered to be two types of American Bulldog, the Johnson type and the Scott type, named after the breeders who were influential in developing them, John D. Johnson and Allen Scott. These are more commonly known as Classic or Bully type and Standard or Performance type.
Appearance
The American Bulldog is a stocky, strong-looking dog. Its coat is short and either white or white with patches. The Johnson type is a larger dog with a shorter muzzle than the Scott type. However, many modern American Bulldogs are a combination of the two types. In general, American Bulldogs weigh between 27 to 57 kg (60 to 125 lb) and are 52 to 70 cm (20 to 28 in) at the withers.
Temperament
An American Bulldog is typically a happy, friendly, and assertive dog that is at ease with its family and fine with strangers as they get to know the stranger in question. They are quite fond of children but sometimes do not know their own strength, thus, as with all dogs, they should be supervised with small children. They bond strongly with their master and family but, because of strong guarding instincts and a somewhat dominant attitude, they need a firm but fair hand; they should be socialized and obedience trained early to expose them to other dogs and people and to ensure that they can be controlled around company as they get older and larger.
Remember, they are working dogs with high energy drives. They need room to expend their energy, and so American Bulldogs do best in a home with a backyard and preferably a "job" to do. A tired well worked bulldog is a happy bulldog. They are not always well behaved towards cats and smaller pets, but correct socialization at an early age can greatly increase the chances of them accepting these animals. This behavior is a reflection of a breed trait called prey drive. High prey drive is a desirable trait in an American Bulldog. A well bred American Bulldog is a catch dog of large herbivores. They can be stubborn with training though once they are trained they tend to obey their masters faithfully. American bulldog puppies can be relatively difficult to housebreak, but it is important to be persistent.