The bull mastiff is a large, muscular dog, and typically has a short coat that is red, fawn or brindle in color. Though some may have a small patches of white, in general white coloring is not an acceptable shade within breed standards, according to the American Kennel Club. Originally developed in England, the bull mastiff was a cross between a mastiff and a bulldog.
An adult bull mastiff weights 110 to 130 pounds and measures as tall as 27 inches at the highest point of the shoulders. A bull mastiff's nose is black, and a dark muzzle is preferred. The ears are medium-sized, and the eyes are dark. The bull mastiff's coat is short and dense. Its body is large and muscular, yet proportionate.