The formidable Tosa Inu is a dog that was bred by the Japanese to feed their desire for a very large and courageous silent fighting dog for the ring sport of pit fighting. The Japanese do not like to lose and when they opened their borders in 1854 and foreign European dogs began to enter the ring and the Japanese were being consistently beaten, they put their breeding expertise to work to produce the Tosa Inu. This breed was perfected from a combination of the Mastiff, the Bulldog, the Bullterrier, The German Pointer, the Great Dane and the indigenous fighting dogs already present in Japan, such as the Akita. The Tosa when trained properly is no different in temperament than any of the breeds which were used in its development....all of them are solidly gentle and affable towards people. The Tosa because of its thick skin and naturally heavy coat has a high tolerance for pain as do most of the dogs bred to be used in the sport of dog fighting. And the Tosa because of the breeds used in its development will not stand down when confronted although usually will not be overly aggressive unless confronted.

The rules of the pit ring in Japan require that the dog be a silent and steadfast fighter and the Tosa Inu lives up to that admirably, never giving in and continuing to fight to the death if necessary without uttering a sound or a bark of any kind. However fighting to the death is not part of the Japanese ritual of dog fighting and seldom occurs for the dogs are pitted together and judged on various standards which are nearly as stringent as the standards required of the Samurai swordsmen....the fight is discontinued after a period of time and points are awarded to the winning dogs with much pageantry and acclaim. The sport of dog fighting in Japan has precise rules and it is stylized nearly as much as the Sumo wrestling events. The Tosa Inu is considered to be the "Sumo" fighting dog of Japan, being large and powerful and persistent. Tradition requires that the Tosa Inu be led into the ring between two human handlers rather than just one as are most of the other breeds and it is possible that both people are actually needed for the Tosa Inu is a very strong and powerful breed. In weight pulls a single dog has been known to pull as much as 3,800 pounds.

The Tosa Inu is not a breed for everyone. It goes without saying that any dog that is that large and that formidable as an adult needs proper bringing up as a puppy. They are naturally a dog aggressive breed but should never be aggressive without provocation. They are affectionate and gentle with their human families and are loyal yet quite tolerant of strangers if brought up correctly. Unfortunately there have been instances where Tosas have been bred irresponsibly and sold to owners who desire to use them as guard dogs or attack dogs and who do not posses knowledge and skill in training such dogs. This has led to some serious problems and ownership of Tosas is outlawed in some parts of the world because of these incidents.