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Boston Mastiff (Boston Terrier & Mastiff Mix): Pictures, Care Guide, Temperament, & Traits

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By Nicole Cosgrove

Parent Breeds of Boston Mastiff

The Boston Terrier grows to around 15 inches tall and weighs 25 pounds, whereas the English Mastiff, one of the largest breeds in the world, can grow to 32 inches and weigh more than 200 pounds. The two breeds couldn’t be more different in their general physical characteristics, which makes the Boston Mastiff, a hybrid breed that combines the two, an intriguing mix.

The size difference means that puppies do not occur through natural or accidental breeding, and they are very difficult to find.

Breed Overview

Height: 20–25 inches
Weight: 80–150 pounds
Lifespan: 8–12 years
Colors: Black, white, brown, tan, fawn, apricot
Suitable for: Experienced owners looking for a loving, energetic dog
Temperament: Loyal, loving, sociable, playful, intelligent

The Boston Mastiff is a very rare hybrid breed because the two parents will rarely, if ever, breed naturally. However, the resulting puppy tends to be sociable and fun, like the Boston Terrier, and tolerant and loving, like the English Mastiff. You can expect an intelligent breed, but you should also expect a big dog, although the size of the English Mastiff is somewhat tempered by that of the Boston Terrier. The Boston Mastiff requires a lot of physical exercise and plenty of mental stimulation.

Boston Mastiff Breed Characteristics


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Boston Mastiff Puppies

It is very rare to find Boston Mastiff puppies, due to the size difference of the parents and likely a lack of interest in the hybrid breed. Therefore, it is difficult to assess how much puppies will cost. Both parent breeds will usually cost around $1,000 to $1,500 as puppies, though, and you should expect to pay somewhere in the region of $800 to $1,000 for the Boston Mastiff.

You will specifically have to look for Boston Mastiff breeders because this pairing won’t usually happen by accident. While the resulting puppy will be smaller than an English Mastiff it will still have to be the Mastiff that is the mother.

If you do find a breeder, ensure you do your research on the breeder. Check out their premises, ask them any questions about the breed, and make sure you get a chance to meet the puppies and at least the mother.

It may be possible to find Boston Mastiff puppies in rescues, although their rarity means that this will be difficult, too. Get as much history about the dog as possible, including the reason why it was surrendered, but bear in mind that most rescues don’t have a full history of the dogs in their care. If you have other dogs already in your household, arrange to have them meet the Boston Mastiff before you bring it home.

The Boston Mastiff is a large breed, topping out at up to 120 pounds as a fully-grown adult, and you can expect your puppy to be large, too. For context, an adult male Golden Retriever weighs around 70 pounds, so a Boston Mastiff can weigh nearly twice as much when it reaches adulthood.

Although the Boston Mastiff is considered a sociable and friendly dog, you should still ensure that your new puppy gets plenty of socialization and training as early as possible. This will help ensure your dog grows up to be confident around strangers and in new surroundings.

Parent Breeds of the Boston Mastiff
Image Credit: (L) Eve Photography, Shutterstock | (R) Kachalkina Veronika, Shutterstock

Temperament & Intelligence of the Boston Mastiff

The Boston Mastiff is rare, and because there are such big differences between the two parent breeds, it can be difficult to predict exactly what you will get with a Boston Mastiff. However, the dog is generally considered a sociable, friendly, loyal, and loving pet that will fit in with most families.

Are These Dogs Good for Families? 👪

The Boston Terrier is considered one of the more accepting small breeds when it comes to living with children. They like to play, and they enjoy company, as well as fun, which means they will put up with the occasional grab and poke. The English Mastiff is also very good with children and is sometimes referred to as a “nanny breed” because it will take care of the children in its care.

The Boston Mastiff, therefore, combines two breeds that are good with children, which means that it, too, should be accepting and affectionate with kids. However, it is still a big breed and accidents can happen. A 100-pound dog can still hurt a very young child, even if by accident, so always ensure that you supervise time between the dog and very young kids.

Does This Breed Get Along with Other Pets?

The Boston Terrier is known for being a friendly breed that will not only get along with children and strangers but also with other dogs and even cats. It especially enjoys having another dog around if that dog is willing to play and run around.

The Mastiff can be more aloof with strange dogs, although it should get along with other dogs in the house if they are introduced from a young age and spend plenty of time together. It is generally recommended that you do not keep two Mastiffs of the same sex in the same house, however.

Whether your Boston Mastiff will get along with other dogs will depend on whether it is more like the hyper-friendly Boston Terrier or the more aloof Mastiff. It should be possible to integrate a Boston Mastiff with other dogs in the home, though, and the same is also true of cats. Dogs should never be left alone with smaller animals because the temptation to chase and hunt an animal like a rabbit may prove too strong even for the friendliest of breeds.

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Things to Know When Owning a Boston Mastiff:

The Boston Mastiff is a big dog, and it needs a lot of exercise to stay healthy and to keep its mind busy. As such, it might not be an ideal breed for apartment living. If you do keep one in an apartment, you will need to make sure you give regular walks. Similarly, the size and strength of the breed means it might not be suitable for seniors. However, its loyal and loving nature means that the Boston Mastiff can be a good choice for active families with plenty of time to dedicate to their dogs.

Food & Diet Requirements 🦴

The Boston Mastiff is a big dog and will have a big appetite. The Mastiff is especially prone to putting on excess weight, so you will need to measure and manage its diet carefully to avoid weight gain. Speak to your vet if you notice your dog has put on too much weight. They can devise a diet plan that will help shed the pounds.

A puppy’s diet needs to include more protein and will usually be high in calories because puppies burn a lot more energy than adults. Puppy foods are formulated to meet these requirements, and you can also get senior foods that meet the specific dietary requirements of older dogs.

Exercise 🐕

All dogs need regular exercise, according to their breed, age, and physical condition. The Boston Mastiff combines the highly energetic Boston Terrier with the Mastiff, which does need exercise but is generally happy with a moderate walk. You can usually expect the resulting hybrid to need a lot of daily exercise. Provide around one hour of walks per day and look for ways to introduce other forms of exercise.

Agility classes can be good because they stimulate the mind as well as exercise the body. Other canine sports classes, especially those requiring strength, will be good for this bulky breed.

Training 🎾

The Boston Mastiff is intelligent, and it can learn very quickly, but it can have a stubborn side so you will need to ensure that training is consistent. Because this is a large breed, you will need to train good manners. Having a 100-pound dog that jumps up to greet everybody it meets can pose problems for you and those around you. Enroll in puppy classes. Puppy classes teach you how to train your dog. They also teach some early, basic commands, and they also allow some safe socialization.

Use positive reinforcement training techniques. The Boston Mastiff can be highly food orientated, which means that treats will prove an invaluable training tool. Reward your dog with treats every time they successfully perform a new command and gradually reduce the frequency at which you give treats once they have learned the commands.

Socialization is an integral part of every young dog’s life. Expose your dog to different groups of people and different settings so that when they get older, they won’t be afraid or apprehensive about meeting new people. Socialization should continue throughout the dog’s life, but it is especially important when they are a puppy.

Grooming ✂️

Both parent breeds have short coats, and the Boston Mastiff will have a similarly short coat. Grooming should be easy. Brush three times a week and brush your dog’s teeth at least three times a week. Nails will need trimming, but how often depends on whether your dog gets regular exercise on concrete and other abrasive surfaces. This may need to be done once every 2 or 3 months. You shouldn’t shave a Boston Mastiff, but you can take them to a professional groomer every few months to ensure they are looking their best and they are well maintained.

Health and Conditions 🏥

The Boston Mastiff combines two very different breeds, and while it does benefit from hybrid vigor, which means that it isn’t as susceptible to some of the hereditary conditions of its parents, there are some conditions you should keep an eye out for. In particular, both parent breeds are brachycephalic, although the larger nose of the Mastiff means that it can go its whole life without suffering any ill effects. But you will need to keep an eye out for signs of brachycephalic syndrome, which can require surgery to correct it.

Minor Conditions
  • Cataracts
  • Cherry Eye
  • Luxating Patella
Serious Conditions
  • Heart Murmurs
  • Corneal Ulcers
  • Brachycephalic Syndrome

Male vs Female

Generally, male dogs will grow to be larger than females, both in height and weight, so you can expect a male Boston Mastiff to weigh over 100 pounds, and even as much as 120 pounds. Females can weigh up to 100 pounds. Females tend to be more aloof with strangers and more subdued than their male counterparts. Males are more likely to bark and be more intense dogs.


3 Little-Known Facts About the Boston Mastiff

1. Mastiffs Are Descended from Roman War Dogs

The giant English Mastiff is descended from Molosser dogs, which were used to hunt lions in the desert. Traders took the breed to the UK, where the Romans took them home to fight in arena battles and used them as war dogs. Although their size and power would certainly point to this kind of use, the breed is known for being loving and affectionate, making it difficult to picture them fighting wars.

2. Mastiffs and Boston Terriers Are Brachycephalic Breeds

Brachycephaly is a condition where the skull of the dog is shortened, and it leads to the short, squat face that is especially prevalent in the Boston Terrier parent breed. The larger nose snout of the Mastiff means that it isn’t as immediately evident in the Mastiff, but it is there. With both parent breeds being brachycephalic, the Boston Mastiff can suffer some of the problems associated with this condition.

3. The Boston Terrier Was Once the Most Popular Breed in the US

The Boston Terrier originates from Boston, and it was such a popular breed that at the turn of the 20th Century it was the most popular breed in the US. Although it has been usurped by breeds like the Golden Retriever and the German Shepherd, it does remain a popular dog in the US, and its popularity is increasing in countries around the world.

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Final Thoughts

The Boston Mastiff is a hybrid that combines the Mastiff and the Boston Terrier: two dogs that, on the surface at least, are very different. The Boston Terrier is a plucky, fun, and friendly small breed. The Mastiff is a giant breed that can be a little aloof around strangers but is loyal and loving with family.

When combined, the resulting mix tends to display the loving attributes of its parents, but it is a large breed and it does require exercise and mental stimulation. And, while intelligent, the Boston Mastiff can be quite independent, which makes training a little bit of a challenge. If you have the patience and the experience, that challenge can be very well rewarded, however.

Featured Image Credit: (L) BIGANDT.COM, Shutterstock | (R) Joseph Gruber, Shutterstock

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