The words Dog Breed Info with the letter D inside of a black paw print

American Mastiff

Information and Pictures

The left side of a tan American Mastiff that is standing on grass and a dirt driveway. There is a bed of flowers behind it.

Duke a good example of an 18-month-old male American Mastiff with a fawn coat.

Other Names

AM Mastiff

North American Mastiff


uh-MAIR-ih-kuhn MAS-tifspeaker


The American Mastiff has a much drier mouth than other Mastiffs. The drier mouth is due to outcrossing the English Mastiff with Anatolian Mastiff, which occurred early in the development of the breed. The American Mastiff is a large, massive and powerful dog. The head is wide, heavy and rectangular in shape. The eyes are amber in color, the darker the better. The ears are rounded and set high on the head. The muzzle is medium sized, and well-proportioned to the head, which has black mask. The nose is black. It has a scissor bite. The neck is powerful and slightly arched. The chest is deep, broad and well-rounded, descending to the level of elbows. The ribs are well-sprung and extend well back. The back is straight, muscular and powerful, with well-muscled and slightly arched loins. The forelegs are strong, straight and set well apart. The hind legs are wide and parallel. The feet are large, well-shaped and compact with arched toes .The tail is long, reaching the hocks. Puppies are usually born dark and lighten as they grow older, some becoming very light fawn by age one; some retain dark hairs. Colors are fawn, apricot and brindle. White markings acceptable on feet, chest and chin/nose. Temperament: Dignity rather than gaiety; quiet, calm, loving and loyal. Protective, but not aggressive.


The American Mastiff loves children and is totally devoted to its family. It is non-aggressive except in those instances when its family, especially the children, are threatened. In those instances it becomes a courageous defender. The American Mastiff is wise, kind and gentle, patient and understanding, very loving with its own people, neither shy nor vicious. It is loyal and devoted. Since these dogs are of the Mastiff type and grow to be very large, this breed should only be with an owner who knows how to display strong leadership.The objective in training this dog is to achieve pack leader status. It is a natural instinct for a dog to have an order in its pack. When we humans live with dogs we become their pack. The entire pack cooperates under a single leader; lines are clearly defined and rules are set. You and all other humans MUST be higher up in the order than the dog. That is the only way your relationship can be a success.

Height, Weight

Height: 28 - 36 inches (65 - 91 cm)

Weight: Males 160 to over 200 pounds (72 - 90 kg) Females 140 - 180 pounds (63 - 81 kg)

Health Problems

American Mastiffs tend to be healthy, happy dogs with fewer reported incidents of many of the health problems you see in other large breeds.

Living Conditions

American Mastiffs do just fine in an apartment with daily exercise; a walk will do, or a run in a fenced-in yard. As they grow older they tend to become a little lazy. They are relatively inactive indoors ("couch potatoes") and a small yard will do.


Mastiffs are inclined to be lazy but they will keep fitter and happier if given regular exercise. Like all dogs, the American Mastiff should be taken on daily regular walks to help release its mental and physical energy. It's in a dog’s nature to walk. They should always be leashed in public.

Life Expectancy

About 10-12 years

Litter Size

About 2 to 5 puppies


The smooth, shorthaired coat is easy to groom. Brush with a firm bristle brush and wipe over with a piece of toweling or chamois for a gleaming finish. Bathe or dry shampoo when necessary. This breed is an average shedder.


Developed by Fredericka Wagner of Piketon, OH, at Flying W Farms by crossing the English Mastiff with an Anatolian Mastiff. The resulting puppies had a firmer, tighter lower lip line and did not drool as much as the average Mastiff; selective breeding thereafter kept the drier mouth.



  • AMBC = American Mastiff Breeders Council
  • BBC = Backwoods Bulldog Club
  • CKC = Continental Kennel Club
  • DRA = Dog Registry of America, Inc.
A large breed, tan with black, extra skinned, soft, thick skinned puppy sleeping inside of a dog crate

"Bean is our American Mastiff. He is 14 weeks old and is very smart. He was extremely easy to potty train. It only took him one week to figure it out."

Front side view of a large breed black and tan puppy with a little bit of his pink tongue sticking out

"Bean is playful when he wants to be but loves sleeping more than anything, well he may like eating a little more. His exercise consists of running up and down the stairs after our other 2 dogs. "

A large breed tan dog with a big head, black face and long soft ears that hang to the sides laying down sleeping on a black leather couch

"Bean refuses to go outside on walks while there is snow on the ground. He learned "sit" and "shake" very quickly, though he will learn anything for a good treat. He is very loving and affectionate. He has to be laying on your lap or beside you while he is doing anything from playing with the other dogs or sleeping. He used to be 7 lbs but what seemed to be no less than a week he was 15 lbs. We can't wait for him to become full grown, but love his puppy days."

A small large breed puppy with a tan body and black face laying down on a tan carpet inside of a house

Bean as a young puppy

See more examples of the American Mastiff