American Mastiff

An Extremely Gentle Giant of a Dog with a Very Sweet Disposition

The American Mastiff is a cross between the English Mastiff and the Anatolian Mastiff, developed with the goal of creating a dog with the disposition, temperament, and appearance of the typical Mastiff, but absent their health problems and excessive drooling traits. The result is a gentle, easy-going giant that loves children and is not aggressive unless its loved ones – especially children – are threatened. Patient, kind, relaxed and understanding, the American Mastiff is never vicious with those it knows or loves, as it is extremely devoted and loyal.


About 20 to 25 years ago, Fredericka Wagner of Ohio’s Flying W Farms, who had bred English Mastiffs for many years, sought to produce a similar breed but devoid of some of its health and drooling problems. She crossed an Anatolian Mastiff and an English Mastiff, ultimately creating the American Mastiff. As a result of a long process of careful breeding, this dog has fewer hip and knee problems, minimal drooling, and a longer lifespan. While not currently registered within the American Kennel Club (AKC), the American Mastiff is recognized by American Mastiff Breeders Council, the Continental Kennel Club, the Dog Registry of America, Inc. and the Backwoods Bulldog Club.


Almost identical to the English Mastiff, the American Mastiff is large and powerful, with a heavy, rectangular, wide head and massive, muscular, deep-chested body. Its coat is short and sleek, usually brown. The dog is characterized by a black face mask.

Most imposing is its size, although this dog does not in any way have a "massive" personality to match its physical bulk. In adulthood, the American Mastiff stands 28 to 36 inches at the shoulder and weighs between 140 to over 200 pounds in adulthood.


Completely devoted especially to children, the gentle American Mastiff will never show aggression unless it detects that you or your children may be in danger. In the face of a threat, your pet will become your children's fearless defender, but otherwise is a wise, patient and calm animal.

Despite its serene nature, you still will need to establish dominance over this dog simply because of its large size. Your gentle pet is so affable, though, that kind, gentle discipline and direction will be all that's necessary to keep your pet "in line." The American Mastiff can be prone to laziness, but regular exercise is important for good health and to keep your pet from getting too comfortable with its natural "couch potato" inclinations.

It's important not to leave the American Mastiff alone for long periods of time, since loneliness can have a deleterious effect on such a sensitive dog. The American Mastiff does not tend to be destructive, but you can simply break your pet's heart if you don't show the love and devotion your gentle pet gives in abundance – and most definitely needs in return. Interestingly, this large pet is able to tolerate the minimal space of an apartment because of its generally lazy nature, but it really is best to give the dog some room to move around in. Suburban life suits this dog well, as does country life.

This is one breed where having children is absolutely a plus. The American Mastiff seems to have a special affinity for children and is so gentle and exceedingly patient and kind with your little ones that you will simply have many special memories of your children and their "nanny dog." American Mastiffs seem to instinctively understand that children are small beings who need protection, and they will do so fearlessly and with their lives if necessary.

Proper Environment

The American Mastiff will not need a lot of exercise, but it does need some – and you may have to coax your pet to get it. The American Mastiff is by its very nature a "lazy" breed, and because it is also a large breed, puppies should not be exercised extremely energetically for the first two years of life. While most breeds finish growing by the end of the first year, the American Mastiff continues growing well into its adolescence, which generally coincides with its second birthday. During this physically formative period, its body can be vulnerable to damage from overexertion.

Taking your pet for daily walk at the very least will help ensure that its exercise needs are always met.


As a result of the successful breed development done by Flying W Farms' Fredricka Wagner, American Mastiffs are exceedingly healthy as compared with the typical Mastiff-type dog. She also eliminated the tendency for excessive drooling which is a relief to owners everywhere. As long as you maintain regular visits to the vet and provide a good quality diet, your pet should have a long healthy life.

However, as with most large breeds, perhaps the only real health problem to watch out for is a condition called bloat. Any deep-chested large dog is subject to bloat, where the stomach becomes hard and distended as a result of "twisting in" on itself. The only true and lasting correction for this is surgery, although in some cases it can be controlled with diet and by feeding your pet smaller meals several times a day instead of one or two large meals at once. Bloat can be fatal if not treated promptly, so if you find your pet is trying to vomit and can't, or acting uncomfortable and distressed in any way, consult a vet immediately.

The American Mastiff has an average life expectancy of 10 to 12 years, quite long for this type of breed.


The American Mastiff has a great personality, is exceedingly easy to take care of, and is very healthy – what more could you ask for? How about easy grooming? Smooth and shorthaired, the coat is very easy to groom and should just require brushing with a firm bristle brush and a wipe down with a piece of soft toweling to produce a gleaming, sleek finish. The American Mastiff sheds an average amount, and only needs to be bathed or dry shampooed if absolutely necessary.


American Mastiff.

Retrieved August 11, 2013.

American Mastiff Breeders Council: A HISTORY OF THE BREED.

Retrieved August 11, 2013.

American Mastiff Dog Breed.

Retrieved August11, 2013.

Flying W Farms: History & Information. THE AMERICAN MASTIFF HISTORY OF THE BREED.

Retrieved August 11, 2013.

Questions people often ask about the American Mastiff...

  • +Is the American Mastiff easy to train?

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