The American Mastiff is a large and massive dog that resembles closely to with the English Mastiff in colour, appearance, size etc. The body has an impression of being slightly longer than taller. The head is moderately broad, heavy and rectangular in shape with dropped ears and kindly wide set eyes with brown colour. The muzzle is of moderate size with a black nose. The muzzle MUST be darker in colour with same colour around eye orbits and extending upward between them. This is called "The Black Mask" and all American Mastiffs must have this mark to meet the standards set for this breed. The neck is powerful with a deep chest and strong, straight back. The tail is wide at the roots, tapering to the end and hanging straight. The legs of American Mastiff are set wide apart and are heavy-boned and strong. The feet are large, round and compact. The dog is about 32 to 36 inches high when fully matured with a weight of 160 to over 200 pounds. Females are shorter and lighter. The dog can sport two types of coats, the very usual short coat and very rare long fluffy coat. The coat can come in different colours.
This breed is NOT recognized by AKC however CKC, DRA, BBC and AMBC do recognize this breed.