The American Mastiff was constructed through selective breeding beginning in the 1980s at Flying W Farms in Piketon, Ohio by esteemed English Mastiff breeder Fredericka Wagner. After years of working with English Mastiffs and observing several of the breed's health problems and unpleasant traits, such as hip dysplasia, weak knees, a short life-span, and excessive drooling, Wagner desired to develop a breed that looked similar to the English Mastiff but had minimal health and drooling issues. Crossing the English Mastiff with the Anatolian Mastiff, an old breed that tends to live long, Wagner created the American Mastiff, which generally drool less, have fewer health problems, and longer life-spans than other Mastiffs. If there was a breed that proved the saying, "You can't judge a book by its cover" true, it's the American Mastiff, whose gentle demeanor is hidden under a large and gigantic appearance. http://www.goenglish.com/YouCantJudgeABookByItsCover.asp In fact, these accepting and non-aggressive pets make wonderful additions in homes with children.

American Mastiffs are known to be happy and healthy dogs, with few health issues compared to other large breeds. However, Mastiffs in general have a tendency to suffer from excessive gas, so it is highly recommended to try dog foods that help to minimize this reaction. In addition to this, Mastiffs often snore when sleeping, which may be a problem to light sleepers in the home, since American Mastiffs like sleeping in the room with family members. http://www.americanmastifffamily.net/faq.htm

Calm and quiet animals, American Mastiffs are not particularly active pets, preferring to be indoors more than outdoors. However, it is essential for their health to get regular exercise, usually by walking them on a leash, as they can be too lazy to run on their own in a fenced yard, especially when they get older. Training American Mastiffs is normally not a difficult task compared to other large breeds. They are sensitive and highly intelligent dogs that respond well enough to their master's steady and consistent tone, so there is often no need to raise your voice or hand to them. Nevertheless, they are pets that need to grow up with rules and respect in the home. Otherwise, they can become unruly and troublesome. Though laid-back and easy-going, Mastiffs were bred as guard dogs, which contributes to the American Mastiff's protective instincts. Oftentimes, they will only attack if their owners are in danger, but it is still wise to train them on how to react to strangers that are friendly or those who pose a threat.http://www.dogbreedinfo.com/americanmastiff.htm