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How To Breed Tosa Inus

Written by Jay
BsC (Hons) Animal Behaviour & Welfare graduate with a passion for advocating for misunderstood animals.
Published on
Wednesday 7 July 2021
Last updated on
Tuesday 9 May 2023
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As a Tosa Inu enthusiast, you may have questions about how to breed Tosa Inus. Or, as a newer owner, you want to refresh your knowledge of this impressive breed. Hailing from Japan, the Tosa is unmistakable with its large size and immense power. As a fighting breed, the Tosa now faces restrictions across the world, and should only be kept by experienced dog owners.

Here, we discuss the Tosa’s background, appearance, and health problems. Full, expert knowledge of each section is essential for any responsible Tosa breeder. Ready to find out more about breeding Tosa Inus? Let’s get started.

Background of Tosa Inu

The Tosa Inu was bred specifically to be a fighting breed. However, over time, this breed has found a place in family homes, home guardianship, and even hog hunting. But how exactly did the Tosa come to exist? And what breeds makeup today’s Tosa? These are important questions to ask when breeding Tosa Inus.


The Tosa Inu, also known as the Tosa-Ken or Japanese Mastiff, is a rare dog breed originating from Japan. Its name hails from its birthplace, the Tosa Province of Shikoku. Today, the Tosa Province is known as the Kōchi Prefecture. Tosa Inus originate from the native Shikoku-Inu, one of six indigenous breeds that were granted “natural monument” status by the Japanese Crown. In 1854, the government repealed the National Isolation Policy, bringing in more foreign tourists. Increasingly, European dogs were pitted against Japanese dogs in fights, and the larger European dogs won. So, this breed was crossed with a variety of European breeds over the coming years. These include the Old English Bulldog, the English Mastiff, the Great Dane, the German Pointer, and the Bull Terrier. The result was a larger, more powerful dog that gave us today’s Tosa Inu.

Between 1924 and 1933, Tosa Inu breeding was most popular and over 5,000 breeders were registered in Japan. Unfortunately, World War II saw the Tosa’s decline towards extinction in Japan. Instead, the Tosa began to flourish more in Taiwan and Korea. Once World War II ended, the comeback of dogfighting caused Japan, Taiwan, and Korea to attempt to bring the Tosa Inu back. This brought out today’s Tosa Inu – a large, athletic dog who is also intelligent and fearless. It became so powerful that it required two handlers to escort it to the fight arena.

The Modern Tosa Inu

In Japan, it is still legal for Tosa Inus to fight in the ring. Modern Tosa fighting is similar to Sumo wrestling. Only male dogs may fight, while females are typically home guardians. The dogs are led to the arena by silk robes, wearing ceremonial robes costing upwards of $30,000. In other parts of the world, Tosa Inus are bred for guardianship and hog hunting.

Tosa Inus are banned or restricted in many countries. Denmark, Spain, France, Romania, Norway, Israel, Turkey, the Bermuda Islands, Portugal, Singapore, New Zealand, Australia, Ukraine, and Belarus either ban or heavily restrict the import and breeding of this breed. This is because of the breed’s reputation as a fighting dog and its dog-aggressive tendencies.

Many breeds make up today’s Tosa Inu. For example, the Old English Bulldog was brought in for its punitive bite and powerful forequarters in 1972. At some point, Bull Terriers were included to increase tenacity. German Pointers, while a seemingly unlikely breed to include in the Tosa Inu, was an important component added in 1876. Firstly, the German Pointer introduced a concordant temperament. Then, it brought its highly-developed sense of smell. This brilliant sense of smell aids breeds like the Tosa in predation. Perhaps one of the last breeds was the Great Dane, added in 1924. The Great Dane brought its massive size and dexterity.


The Tosa Inu is a large, sturdy dog with an athletic and majestic build. It has drooping ears, a short coat, a square muzzle, and a thick tail that gives it a distinct presence of power. Before breeding Tosa Inus, you must acquaint yourself with the ideal specimen of the breed.

Size and Weight

The Tosa Inu’s size and weight vary depending on sex. Firstly, male Tosa Inus stand between 60 and 65cm tall at the withers. In contrast, female Tosa Inus stand at 55 to 58cm at the withers. The FCI states a minimum height of 60cm for males and 55cm for females. Interestingly, there is no upper limit for this breed. Also, Japanese dogs tend to be lighter and shorter than those born in other countries. These dogs weigh between 80 and 135lbs, while the dogs outside of Japan may weigh 130 to 200lbs.


Tosa Inus have short, hard, and dense coats. The FCI breed standard describes the most common coat colors as red, apricot, brindle, fawn, and black. The breed may have small white patches on the chest and feet, too. Other coat colors suggest that the dog in question is not a purebred Tosa Inu.

Distinct Features

The Tosa Inu is a distinct breed. With its athletic build and characteristic square muzzle, the Tosa resembles a Mastiff but has much more agility. The Tosa’s low-hanging tail is also thick at the base. These features gave these dogs fighting prowess, but today’s Tosas use their athleticism to guard family homes or hunt instead. One of their most noticeable traits is their well-muscled body and broad chest, with a level topline and some loose skin. The Tosa also sports noticeable jowls. However, unlike other dogs with similar jowls, the Tosa tends to drool less.


Tosa Inus are quietly affectionate with their families. With intensive training and a greatly knowledgeable owner, these dogs can be loyal, laid-back, and sensitive and learn to pay close attention to commands. However, they are aloof with strangers. The breed is, by nature, watchful of other dogs and can become dog aggressive. In contrast, Tosa Inus are not overtly aggressive towards humans, as this is uncharacteristic of the breed. In fact, the German Pointer was included in the development of this breed largely for its temperament. German Pointers are well-known for being affectionate, cooperative, and highly trainable dogs. With this being said, however, Tosa Inus lack the pointing instinct of the German pointer, instead, finding great competency as guard dogs.

breeding tosa inus
Tosa Inus have an athletic built.

Common Health Issues for Tosa Inus

Despite being tough dogs, Tosa Inus still struggle with some specific health problems. The most common problems include skin allergies, hip dysplasia, hyperkalemia, and uveodermatologic syndrome.


Tosa Inus are prone to allergies. The symptoms of allergies in dogs include itchiness, hives, swelling of the face, ears, and lips, red skin, sneezing, ear infections, runny eyes, and constant licking. Frequent itching and licking lead to hair loss and inflamed skin. If your pup shows signs of an allergic reaction, be sure to speak to your vet about your options. Medication can help to manage the symptoms, and by working with your vet, you may be able to eliminate the allergen from your home.

Hip and Elbow Dysplasia

In short, hip dysplasia is the abnormal formation of the hip socket in dogs. In its most severe form, hip dysplasia eventually leads to lameness and arthritis of the hip. This polygenic disorder is common in larger breeds. As such, the Tosa Inu may be prone to hip and elbow dysplasia.


Hyperkalemia occurs when the potassium levels in the blood are higher than normal, typically as a result of renal disease. This is a concern as potassium is essential for nerve and muscle cell function. Interestingly, pseudohyperkalemia is more common in East Asian dog breeds. These include the Shar-Pei, Akita Inu, Shiba Inu, and the Jindo. Studies have found that these breeds are naturally inclined to have high-potassium red blood cells without any underlying renal disease. This means that these dogs often lack the typical symptoms of hyperkalemia. Instead, they may exhibit mild nonregenerative anemia, and increased red blood cell width.

Uveodermatologic Syndrome

Uveodermatologic syndrome is an autoimmune disease of Tosa Inus, Akita Inus, and Chow Chows. The dog’s immune system attacks pigment cells in the body and even the light-sensing cells in the eye. This causes eye inflammation, whitening of the hair, loss of pigment in the skin (vitiligo), and sometimes meningitis. In most cases, eye inflammation starts first. As a result of eye inflammation, affected dogs may develop extreme sensitivity to light and lose their pupillary reflexes. This can progress to retinal detachment and cataracts, and ultimately, total blindness. Dogs with this condition need immunosuppressive therapy as well as corticosteroids to treat eye problems.

Breeding Tosa Inus

Breeding Tosa Inus is not a task that should be taken lightly. In light of BSL and the breed’s dog-aggressive reputation, you must breed these powerful dogs with the best intentions. You must breed for excellent temperament and to improve the breed above all else. This means that you must not rush your breeding program, and it is worth waiting months or even years to find the best stud and dam that meets these requirements. You must also check your state’s laws surrounding this breed before buying, selling, or involving yourself in the breed circle. And, perhaps above all, never breed the Tosa Inu for the purpose of dogfighting.

Litter Size

The average litter size of the Tosa Inu is 6 to 12 puppies. However, litter sizes depend on the dam’s size, age, health status, and fertility. The stud’s sperm quality and physiological attributes also play a role in litter sizes. When asking how to breed Tosa Inus, it is important to breed not just for large litter sizes, but for sound temperament and conformation as well. You must look into your dogs’ health records and temperament above all else.

Tosa Inu Pregnancy

You can expect your Tosa Inu to be pregnant for 60 to 64 days. In addition, their heat periods have a six-month interval. Because of this, this breed typically only breeds once or twice a year. Plus, there are no official statistics to suggest how often Tosa Inus need C-sections. However, larger litter sizes may cause C-sections to be a necessity.

Some dogs experience dystocia when giving birth. In short, dystocia is a “difficult birth.” Warning signs that your bitch is struggling include weak straining for more than two hours without delivery, more than four hours passing between puppy deliveries, and strong contractions for more than 30 minutes with no delivery. Any green discharge, bloody discharge, or excessive clear discharge also indicate dystocia. You must seek the help of your vet if your bitch shows any of these worrying signs.


The cost of buying a Tosa Inu puppy ranges from $1,800 to $2,200 or more. This price depends on the bloodline of the puppy as well as the preference of the breeder themselves. You must note that this price does not include the cost of raising your puppy. Indeed, you will need to consider the cost of microchipping, vaccinations, neutering, training classes, equipment, and feeding your puppy. You will also need to consider erecting a sturdy, tall fence around your yard to keep this breed responsibly.

As well as this, you must consider the potential issues that come with owning this breed. Your insurer may refuse to sell you homeowners liability coverage, especially if your dog has shown signs of aggression in the past. Similarly, renters insurance may come with a higher premium or may not cover damages that your breed causes. These are risks that you must consider before buying this breed.

breeding a tosa inu
You should breed your Tosa Inu responsibly.

Tosa Inu Breed: FAQ

Have any more questions about breeding Tosa Inus? Feel free to refer to our Frequently Asked Questions section for more details. If in doubt about your pet’s health, always ask your vet for advice.

Are Tosa Inus dangerous as pets?

Tosa Inus are not necessarily dangerous as family pets, but there are several important things to consider. First and foremost, Tosas require experienced owners with physical and mental strength. Your Tosa’s strength far outweighs your own. In fact, Tosas are known to pull weights over 1585 kg. You must be able to control your dog in your home and in public. Next, you must consider any other pets in your home. A Tosa can easily overpower another dog and will defend itself without fear. As such, the Tosa does best when kept as the only dog in the household. Many breeders also specifically advise against keeping two Tosas of the same sex in the home.

But, with all of this in mind, the Tosa is also a mild-mannered and loving family pet. Their protective and obedient qualities make them excellent home guardians, too. However, these dogs are not a good choice for first-time owners who want a family pet.

What are the exercise requirements for Tosa Inus?

Your Tosa needs at least one hour of exercise per day. Without enough exercise, your Tosa may become difficult to control and more prone to destructive behaviors. To prevent this, provide long walks or jogs twice per day. You should also provide your Tosa with opportunities to exercise in a large yard. This yard must be well fenced in to prevent escape as well as other animals getting in.

When walking your Tosa, you must be mindful of other people and dogs. Your Tosa should stay on a leash at all times, not just for the safety of other dogs, but your own dog’s, too. If an off-leash dog runs towards your dog, you must be able to control your own dog well enough to retreat from the situation quickly and calmly.

Why are they banned in some countries?

Tosa Inus are closely associated with dogfighting. As such, many countries ban them to reduce the temptation of this highly unethical blood sport. Then, comes the issue of inter-dog aggression. While Tosas are laidback and affectionate companions, their instinct to defend is strong and they will not hesitate to protect themselves from another dog. This is especially true for dogs who are not well-socialized as puppies. Some dogs may misinterpret the body language and intentions of other dogs as threatening and will react accordingly. Lastly, Tosa Inus are incredibly powerful dogs and can be difficult to control. Inexperienced owners sometimes wrongfully assume that they can control these dogs, only to find themselves in situations where their dog has bitten another dog or person due to instinct.

How much grooming do they need?

Tosa Inus are light to medium shedders. Their short coats are easy to maintain and only need occasional brushing. However, more frequent brushing can be done to reduce shedding. As Tosas are prone to allergies, make sure to check for itchy, inflamed skin as you groom your pup!

Are Tosa Inus easy to train?

The Tosa Inu is a highly trainable breed. It responds best to positive reinforcement, and as always, punishment and physical coercion should never be used. You must have an expert understanding of dog training before buying a Tosa, as a high level of obedience is needed if you want to keep your dog responsibly.

The Tosa Inu has fantastic guardian abilities and is generally laidback in a family setting. Compared to Mastiffs, these dogs are more agile and trainable. Like any breed, a Tosa is capable of being a loyal family member when given the proper environment and attention it needs. However, these powerful dogs are not for beginners. You must thoroughly research this breed before adopting a Tosa, and adhere to any laws in your state regarding it too.

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