The American Bullmastiff was a name assigned to a number of creations throughout the 20th century, from common working bulldog and mastiff crosses to various Bandogge types and also the American bloodlines of English Bullmastiffs. The most common recipe for creating the breed has traditionally been a mix of the American Bulldog and English Bullmastiff examples, but today's incarnation also employs the blood of English Mastiffs, Saint Bernards and Bandogges, creating a more massive and easy-going companion breed which possesses excellent guarding qualities. Two main types exist within the breed, these being the lighter and heavier varieties, as per their breeding. The lighter variant is seen as the ideal working dog, believed by its fanciers to be much closer to the original Gamekeeper's Nightdog than the modern Show representatives of the Bullmastiff breed, while the heavier type is primarily an urban pet, strongly influenced by the English Mastiff, which it resembles quite a bit. Still unknown and unrecognized, the American Bullmastiff is slowly gaining acceptance in America and is said to be healthier than its parent breeds.
Devoted to its owner and loving of children, this gentle giant is an excellent family pet, but can be overly protective at times. The American Bullmastiff generally responds well to obedience training, although some specimens are known to be quite stubborn and undemonstrative. The body is well-boned, muscular and wide-chested, with a powerful head and sturdy legs.
The tail and ears are left in their natural state. When solid, the short coat comes in fawn, brown, black and brindle colourings. Small white markings on the chest and paws are accepted, but not preferred. For white-based dogs, darker markings of various shades, preferably red or brown, on the head are valued, with uniform white dogs being undesirable. Average height is around 30 inches, although smaller examples exist.