Tosa originated in the second half of the nineteenth century. The breed started from the native Shikoku-Inu, an indigenous dog weighing about 25 kilograms (45 pounds) and standing about 55 centimetres high, which closely resembles the European Spitz. These dogs were crossed with European dog breeds, such as the Bulldog in 1872, Mastiff in 1874, St. Bernard, German Pointer in 1876, Great Dane in 1924, and the Bull Terrier.
The Tosa has unmatched loyalty to its master and is very good with children and people it knows. They are an intelligent breed that know when there is a threat; are known to attack if there is a threat, and is very protective of other family pets. Generally cannot live with another dog unless they have grown up together or related. The breed favors its "den" (i.e. house, car, and property in a home situation) and "pack" (i.e. human family in a home situation) and is very affectionate to its family. It is poised, but when the occasion demands, eager and alert; both fit and willing to serve in its capacity as a companion, watchdog, guide dog for people who are blind, herding dog, fighter, or guardian, whichever the circumstances may demand.
Proper socialization as a puppy is one of the two key factors which determines what a dog's temperament will be as an adult. Genetics is the other. They go hand-in-hand; there is no guarantee that a dog with poor genetics can be trained to be stable and friendly, and by the same token the best genetics are meaningless if the dog is not well-socialized as a puppy. Ideally, a Tosa should be alert and fearless in defense of its den and pack, but loving and non-aggressive within the home environment and to strangers that its master is at ease with. The Tosa is unmatched in strength and pain tolerance but is as clever as it is strong.
Both parents should have the following certificates: CERF (eyes) and OFA (hips and elbows). Also prone to bloat. Ask about bloat in the lines. Bloat can be a major problem in these large dogs.
