In Japan, Tosas are the canine equivalent of Sumo wrestlers and are treated with great honor and ceremony. In the United States, the Tosa serves as a companion dog and guardian of the home.

The Tosa, also known as Tosa-Inu, Tosa-Ken, Tosa-Token, Japanese Fighting Dog, and Japanese Mastiff, is a large, powerfully athletic dog with a robust, agile body. The body is slightly longer than tall. The head is large with a broad skull, fairly abrupt stop, a moderately long squared-off muzzle, pendulous flews, and clearly observable dewlap. There is wrinkling on the head, particularly when the dog is alert. Ears are of medium size, pendant, and set high falling along the checks. The eyes are small, dark and almond-shaped, with a dignified expression. The tail is uncut, very thick at the base, and tapering to the tip to reach the hocks. The overall appearance should be that of a massive but dynamic and flexible athlete, a true canine samurai.

The Tosa is normally a tranquil, quiet, and obedient dog with a calm but vigilant demeanor. The Tosa is quietly affectionate with its own family but may be somewhat aloof with strangers. Very attuned to his master's wishes and greatly sensitive to the tone of ones voice. Protective and loyal. Tosas show remarkable acceptance of children. However, due to the Tosa's size, he should not be left with children unsupervised. The owner must learn to control the Tosa, as the breed is too large and strong to be unmannerly. The Tosa tends to be dog/animal aggressive. Keep the Tosa away from other dogs that may want to fight. They are not recommended in a home with other dogs of the same sex, size and temperament. They have a very high pain tolerance due to their fighting origins. This breed requires a strong and experienced owner capable of dealing with a large, powerful animal. They are highly intelligent and do not need repetitious training, but do require an equable, consistent, friendly approach. With proper training and control, the Tosa can be a good family companion. Self aware, a very good guard and watchdog. This breed is also by nature watchful of other dogs and may react aggressively to dogs it considers intruders. Overtly aggressive behavior toward humans is uncharacteristic of the breed and highly undesirable. The Tosa responds best to positive-enforced training methods because of an inherent desire to please its owner. This breed matures slowly and individual dogs may not reach their prime until as late as four years of age. Protection training and Schutzhund are not recommended. This is NOT a breed for beginners.

• Is massive and powerful
• Has a short easy-care coat
• Makes an imposing watchdog
• Is serious and self-assured with strangers, yet generally mild-mannered unless aroused
• Compared to other mastiffs, is more athletic, more agile, and more responsive to training.

A Tosa may be right for you

• A huge dog who takes up a lot of space in your house and car
• A heavy dog who wants to sit on your feet, lie on your lap, and lean his weight against your leg
• Rowdiness and exuberant jumping when young
• Destructiveness when bored or left alone too much
• Aggression or suspiciousness toward strangers when not socialized properly
• Aggression toward other animals
• Strong-willed mind of his own, requiring a confident owner who can take charge
• Shedding and slobbering
• Snorting, loud snoring and gassiness (flatulence)
• Serious health problems and extremely high maintenance costs
• Legal liabilities (public perception, future breed bans, insurance problems, increased chance of lawsuits)

A Tosa may NOT be right for you

If you're considering an adult Tosa... There are plenty of adult Tosas who have already proven themselves NOT to have negative characteristics. If you find such an adult, don't let "typical breed negatives" worry you. When you acquire an adult, you're acquiring what he already IS.