Despite not being well-known, the Tosa is an old breed that dates back to the 1800s. Originally created to be a fighting dog, the Tosa is now revered in Japan as an ideal companion, an avid protector and family dog, and is treated with great respect. The American Kennel Club (AKC) labels the Tosa as the canine equivalent of a Sumo wrestler, so great is the honor and ceremony surrounding this breed today.
1. The Tosa was Created for Dogfighting
The Tosa as a breed originated in the Tosa province (now called Kochi Prefecture) on the Japanese island of Shikoku. The breed was developed in the late 1800s in response to the unfortunately-common sport of dogfighting. The Shikoku Inu was the ideal choice as a fighting dog until Westerners arrived in the 1850s, at which point Inu owners saw an opportunity to breed a bigger, more ferocious dog. In homage to this history, the Tosa is also known by the names ‘Japanese Fighting Dog’ and ‘Tosa Inu’ along with the more common ‘Japanese Mastiff.’
Note: Although dogfighting is still legal in Japan, it is outlawed in the U.S. and most other countries. If you suspect a dog is being abused or forced to fight, contact your local authorities.
2. The Tosa is a Designer Mutt
Interestingly, the Tosa was not originally created by exclusively mixing mastiff breeds. Instead, the Japanese Mastiff was created by deliberately and sequentially breeding the Shikoku Inu and resulting litters with other established breeds for specific characteristics (an early example of the designer breeds that are so popular now).
First, the Shikoku Inu was mixed with Bulldogs around 1872. Actual mastiffs were not introduced until 1874, which provided the Tosa’s characteristic bulk. German Pointers were used in 1876 and Great Danes in 1924 to add the height and length that makes up the Tosa breed as we know it today. Saint Bernards and Bull Terriers were also allegedly used for breeding, but there are no verified accounts with timelines to confirm when this might have happened.
3. The Tosa is the Largest (Non-Native) Japanese Dog Breed
The Tosa is the largest Japanese dog breed by a large (very large) margin. However, it is important to note that the Tosa is recognized as a Japanese dog breed, but not a native Japanese dog breed. There are only six recognized native Japanese dog breeds: the Akita, Shikoku, Kai Ken, Kishu Ken, Hokkaido, and Shiba Inu.
The distinction comes from the breeding lines: native breeds were derived exclusively from dogs originating in Japan. Non-native breeds were either created in Japan or are a designer mixture of Japanese and non-Japanese dog breeds. So the Tosa, much like the Japanese Terrier, is therefore classified as a Japanese non-native breed.
4. The Tosa is a Heavier But Shorter Mastiff Breed
Like most mastiff breeds, the Tosa can get quite large: between 100 and 200 pounds and up to 23.5 inches from its paws to withers (e.g., shoulders). What is interesting about their structure is that they are heavier than many other mastiff breeds, but also significantly shorter.
In terms of weight, only the English Mastiff and Spanish Mastiff reach 200 pounds or heavier on average. The English Mastiff can get up to a whopping 230 pounds (typically males) and the Spanish Mastiff tops out at 200 pounds, just like the Tosa. The Pyrenean Mastiff gets close, but at its heaviest averages out at 190 pounds. The Tibetan, French, and Neapolitan Mastiffs stay under 150 pounds.
But the Japanese Mastiff only gets up to 23.5 inches on average, making it the shortest mastiff breed. The French Mastiff is the next smallest: this breed averages between 23 and 26 inches. The Tibetan Mastiff gets ups to 26 inches, the English Mastiff averages up to 30 inches, and the Neapolitan and Pyrenean Mastiffs get up to 31 inches.
The Spanish Mastiff pulls ahead in this category: they can get up to an impressive 35 inches in height. This puts approx. 11 inches (close to a foot!) between the Tosa and the Spanish Mastiff, despite being close to the same weight on average.
5. The Tosa Has an Average Mastiff Lifespan
The Tosa has a lifespan of between 10 and 12 years. This is a long lifespan not only in comparison to other large breeds, is actually more common for mastiff breeds. The Tibetan Mastiff, Pyrenean Mastiff, and Spanish Mastiff also all have an average life expectancy of between 10 and 12 years.
Only the English, Neapolitan, and French Mastiffs have a shorter life expectancy. The English Mastiff lives between six and 10 years and the Neapolitan Mastiff has an average lifespan of seven and nine years. The French Mastiff (also known as the Dogue de Bordeaux) has the shortest potential lifespan: they may live just five years or up to eight.
6. The Tosa is Slow-Growing
Mastiffs may have longer lifespans, but this may be in part due to their slow growth rates. It can take the Japanese Mastiff up to four years to completely mature, much longer than your average dog. Most large dogs must be kept calmer as puppies to avoid damaging their growth plates as they mature, but this is less of a concern with the Tosa.
Additionally, the Tosa is a low-energy breed that needs less exercise than many other working breeds. Daily walks and playtime in the house or a yard should suffice for this dog. Once the Tosa is older, they also excel at longer, but steady-pace physical activities like hiking. For those interested in competition, the Tosa excels in the AKC’s Working Dog Sport performance event and obedience events.
