American Bulldog

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.
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White and brindle American bulldog.
Photo: Pet Profiles - Isabelle Francais

Height: 21-27 inches
Weight: 60-120 lbs.
Life Span: 11-12 yrs.
Breed Group: Guardian Dogs 
Overview
The self-assured American bulldog is alert, outgoing, and friendly with family members and others accepted by the family, but is wary of strangers and may be aggressive toward other dogs.
It gets along with children and other animals, including cats, if socialized with them at an early age. Obedience training should also begin early, as American bulldogs can be very stubborn.
Appearance
The coat is short and stiff to the touch. Coat color is white, white with brindle or red, or brindle or red with white.
Grooming & Exercise Needs
The American bulldog requires only a quick brushing weekly. If not used as a working dog, it needs brisk daily walks.
Origins
Derived from English bulldog stock, the American bulldog originated in the United States in the 18th century. Traditionally, this breed has been used for working cattle and hogs and as a watchdog.
Special Alerts
The American bulldog is not a good choice for inexperienced dog owners and is unsuited to city or apartment life unless well trained and sufficiently exercised. Breed-related health concerns: hip dysplasia, Demodex mange, atopy.