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Dog Breeds

Bullmastiff dogs are loyal, trusting, and gentle giants that offer only great companionship. If you’re fond of big, smart dogs with sweet dispositions, learn more about the lovable bullmastiff.

Bullmastiff Overview

COMMON NAME Bullmastiff
PET HEIGHT 24 to 27 inches
PET WEIGHT 100 to 120 pounds
LIFESPAN 7 to 9 years
GOOD WITH children, families, seniors
TEMPERAMENT friendly, gentle, outgoing, playful
VOCAL LEVEL infrequent
BREED SIZE extra large (101 lbs. or more)
COLORS fawn, red
PATTERNS brindle
OTHER TRAITS apartment-friendly, easy to groom, easy to train, good hiking companion, highly territorial, high potential for weight gain, high prey drive, prone to health issues, strong loyalty tendencies

What's a bullmastiff? Not quite a bulldog or a mastiff, it's the best of both breeds in one. If you want a well-trained, formidable guardian who also adores you and your children—and welcomes all belly rubs, ear skritches, and full-body hugs, this is the dog for you. Bullmastiffs couldn't hide their devotion even if they wanted to, as 130 pounds of love heading your way is hard to miss!

Breeders Steve Krulish and Jackie Smith own Stonebull Bullmastiffs in Swanzey, N.H. Smith says bullmastiffs "are intensely loyal with long memories. They don't seem to feel the need to have other doggie friends, but rather crave human companionship." So to make sure this dashing pooch has a wonderful life with you, train him well and shower him with affection.


Stately and strapping, with his large head held high and a focused gaze, a bullmastiff is an attractive dog. His sturdy, wide legs support a deep chest, broad shoulders, and sloping hindquarters. He has a square, muscled body inherited from his mastiff ancestor that wiggles slightly when his tapered tail whips at full speed.

His bulldog lineage appears in the wrinkles on his forehead and the folds across his shortened black cube of a muzzle. He's really not as sad as he appears—quite the opposite. But in true bully fashion, his jowls hang with a slight frown, and his rounded deep-set brown eyes appear a little wistful.

A bullmastiff's sleek, dense, and short coat is usually fawn or red, with accents of black encircling his eyes and inking his V-shaped ears as they point down the side of his cap.

Males weigh between 110–130 pounds, and females range from 100–120 pounds. A bullmastiff meets you at hip height or higher, slipping the crown of his head under your palm for easy pats. Standing 27 inches at the withers is pretty common for this large working dog breed.


Under the mammoth physique of a bullmastiff dog is a peaceful cuddle bug who craves your company. While each pup's personality is unique, a bullmastiff will typically want to be in the same room with you, and perhaps even by your feet, next to you, or actually on you as much as he can.

But this behavior doesn't happen automatically. Like many working dogs—and dogs in general—a bullmastiff becomes his best self with proper no-fear and positive reinforcement training, starting when he's about 10 weeks old and after his vaccinations are complete. "It's been our experience that it takes a certain kind of human temperament for a bullmastiff to thrive in a family environment," Smith says. "Folks who are comfortable setting realistic expectations for training and behaviors, and have consistent follow-through, would be best."

As docile and sweet as a bullmastiff's temperament might be, he's still more than 100 pounds of canine energy—and that requires loving but firm guidance to control. Training should include setting boundaries early on with a bullmastiff, and don't stop with puppy kindergarten and socialization training. Continue his training with regular refresher courses so he always understands he isn't the leader of the family.

Krista Sirois, DVM at Florida Veterinary Behavior Service, emphasizes the importance of socializing your bullmastiff so he has rose-colored glasses: He should see new people, animals, and situations as good things.

"Socialization is so important in all breeds, but when you have a dog that's going to be 120 pounds, there's just an added layer," Sirois says. "You want to make sure you know that your dog has good manners and that they're not afraid of things."

Smith adds that bullmastiffs "have a hard time with 'no' sometimes meaning 'maybe.' They tend to be quite literal in that regard. Being inconsistent sets them and the family up for unfair expectations." She says they're not the best breed choice for first-time dog owners.

Bullmastiffs fall under a different classification of working dogs in that they don't need daily intense exercise to be healthy and on their best behavior. Regular walks throughout the day and praise reinforcement of good habits should help keep your bullmastiff content. However, it's essential to tap into his intelligence and natural abilities with agility sports and tracking games, or to train him as a therapy dog.

Bullmastiffs are relatively quiet hounds who don't bark much and are known to be gentle giants, but there's no need to doubt a bullmastiff's watchdog abilities. He has a history of roaming large country estates with gamemasters in search of poachers, so he's dedicated to his family and will alert you if anything seems amiss. As with any dog, make sure to socialize your bullmastiff so he learns to practice good manners around everyone—even visitors.

Living Needs

Bullmastiffs need a secured, fenced area in which to exercise, and shouldn't be taken off-leash except in his home environment. Because he doesn't have to always be on the go like other working breeds, he might do well as an apartment dweller if he is taken outside to stroll and sniff a few times a day.

But be aware of how much exercise they're getting—as with all giant dog breeds, it's possible for them to work out too much, especially when they're young and still growing. "You're not looking for them to be a marathon partner," Sirois says. "It's not good for them to have repetitive, stressful strain on the joints." So if you're looking for a jogging buddy, this big guy might not be for you. But nice, long walks will suit him just fine.

Bullmastiffs aren't fond of hot and humid conditions, so make sure to have a cool place for him to rest. They shouldn't overexert themselves during exercise, especially when the summer heat is at its peak, so choose cool mornings or evenings for your steady walks.

Because they are so big, some owners might be hesitant to let their bullmastiff mix and mingle at dog parks, especially with the littlest guys (we're talking Yorkies or Chihuahuas). While bullmastiffs do have high prey drives, Sirois says bullmastiffs weren't bred to be aggressive toward other dogs, and with proper supervision and socialization from an early age they should do well around canine friends.

"I see dogs [who can be uncomfortable around other dogs] every single day," Sirois says. "Sometimes there's a genetic component, but often it's just poor socialization."


A bullmastiff won't need a lot of grooming, but he isn't always the best roommate for two reasons: slobber and flatulence. He's a brachycephalic, or flat-faced dog, and he drools a lot; and the way he eats challenges his digestive system, which causes noxious fumes. A veterinarian can advise on how best to keep his mask folds clean and give you methods for mopping up dribbles, and dietary recommendations for—well, the other stuff.

Your bullmastiff puppy will grow (and grow fast!) until he's about 2 years old. Sirois recommends feeding him large breed puppy food instead of regular puppy food to help protect his joints.

He'll shed a little bit, especially during the spring and fall, but a quick brushing through the week will keep him neat and tidy. If he smells less-than-fresh, give him a bath. A frequent routine of dental care, nail trimming, and ear checks keeps a bullmastiff looking spiffy.


A bullmastiff is a lot to love, but like many large dogs, only for a short time. His average lifespan is 7–9 years. And similar to dogs his size, there are few medical concerns to understand.

One of the biggest issues to be aware of is bloat. Sirois says this is a condition all large, deep-chested dogs are susceptible to—and it can be deadly. Bloat requires emergency surgery so a veterinarian can untwist the stomach, among other things.

"Unfortunately, they've done so many different studies looking at what predisposes to bloat, like should they eat and then exercise, should they not, should you raise their bowl, and there's nothing that has come out as a clear 'yes, this is likely to cause bloat,'" Sirois says. "So there's not a lot of good guidelines other than know that it's a possibility … know what the signs are, and [know] how to jump on it immediately."

Sirois says it's a good idea for owners of these large breeds to tack their dogs' stomachs as a preventative measure against bloat. For other potential health issues, she recommends getting your bullmastiff screened for any heart conditions, hypothyroidism and progressive retinal atrophy.

Large dogs like bullmastiffs are also prone to elbow and hip dysplasia, a painful and degenerative joint condition that's usually hereditary. Medication may help for a while, but surgery is often necessary in later stages. Consult with a veterinarian about genetic factors, progressive age-related testing, and exercise recommendations.


Sometimes referred to as the "Gamekeeper's Night Dog," bullmastiffs originated in England in the mid-1880s when gamekeepers on expansive country estates struggled to keep poachers from stealing. Because the act was a criminal offense, most landowners wanted to capture poachers, not mangle them. The goal was to create a dog that was quick and assertive, but also even-tempered. According to the ABA, breeding mastiffs and bulldogs together developed an imposing animal that could track with stealth, run fast, and then pin down a trespasser until the gamekeeper arrived to haul him away. This new dog's cunning abilities protected the lives of gamekeepers and poachers alike.

These impressive canines soon hit the British competition circuit, as gamekeepers vied for bragging rights over their bullmastiffs' prowess and formidable presence. As dog shows became more popular in the early 1900s, bullmastiff breed fanciers pushed for recognition with England's Kennel Club, which was granted in 1924.

Bullmastiff dogs were imported to the U.S. in the 1920s by oil magnate John D. Rockefeller. He wanted them to roam the grounds of Kykuit, his country estate in the Hudson River Valley of New York. The East Coast elite couldn't help but notice the majestic presence of this new dog, and the American Kennel Club recognized purebred bullmastiffs in 1933.

If you're wondering about the difference between bullmastiffs and English mastiffs, the first variant is size. English mastiffs are about 100 pounds heavier than bullmastiffs. English mastiffs also aren't as "square" in their bodies as bullmastiffs. Other than that, they're both descendants of the giant ancient molosser, they have similar temperaments, and they make good family dogs.

Fun Facts

Many bullmastiffs share celebrity status with such diverse talented owners as folk legend Bob Dylan, movie star Marlon Brando, pop superstar Christina Aguilera, and rocker and philanthropist Jon Bon Jovi.
Sylvester Stallone's own beloved pet Butkus the bullmastiff appeared in the original 1976 Rocky and again in Rocky II.
NFL team the Cleveland Browns have a bullmastiff mascot, SJ. He took over from his father, Swagger, in 2019 when the elder retired after five years of leading football players out of the tunnel each game day.