Bullmastiff dogs are loyal, trusting, and gentle giants that offer not only great companionship, but also intense protection. If you’re fond of big, smart dogs with sweet dispositions, learn more about the lovable bullmastiff.
By Tracey L. Kelley
Breed Group
Dog Size
Other Traits


  • 24-27 inches
  • 100-120 Pounds
life span
  • 7 to 9 years
breed size
  • extra large (101 lbs. or more)
good with
  • children
  • seniors
  • families
  • gentle
  • friendly
  • outgoing
  • playful
  • aggressive
  • high
shedding amount
  • seasonal
exercise needs
  • medium
energy level
  • calm
barking level
  • infrequent
drool amount
  • high
breed group
  • working
coat length/texture
  • short
  • red
  • fawn
  • brindle
other traits
  • easy to train
  • easy to groom
  • prone to health issues
  • highly territorial
  • high prey drive
  • high potential for weight gain
  • apartment-friendly
  • strong loyalty tendencies
  • good hiking companion

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 and 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 typical characteristic of a bullmastiff is he’ll 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 the leader of the family isn’t him.   

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.” Her recommendation is that 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 less likely to bite, 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 alert, highly territorial, and protective of his human family. His imposing presence is usually enough to keep intruders away, but he’ll do whatever it takes to make sure that happens. 

Living Needs

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

Unfortunately, many bullmastiffs can’t mix and mingle at dog parks. There’s too much territorial tension with other dogs, especially those of the same sex. Even even if they’re raised with canine pals from a young age, one bad experience is all it takes for a bullmastiff to hold a stubborn grudge against other dogs. Plus they don’t want to compete for your affection. Bullmastiffs also have high-prey drives, and this doesn’t really change even if they’re puppies when introduced to cats or small dogs. In the yard, they’ll zip after wildlife, too. 

So whether you choose a bullmastiff puppy or rescue an adult, you’ll probably have a one-pet household. 

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 steady walks.


A bullmastiff won’t need a lot of grooming, but he isn’t always the best roommate for two reasons: slobber and flatulence. As a Brachycephalic, or flat-faced dog, 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, methods for mopping up dribbles, and dietary recommendations for—well, the other stuff. 

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. 

“We encourage folks considering a bullmastiff to visit the American Bullmastiff Association (ABA) web page,” Smith says. “Click on the ‘Health’ tab, which provides information on common conditions and diseases, along with additional information on bloat, cancer, kidney disease, hypothyroidism, panosteitis, and sub-aortic stenosis.”

The ABA clarifies that panosteitis is a “growing pains” illness that causes sudden lameness when dogs are approximately 5 to 18 months old, but eventually goes away as the dog ages. 

Sub-aortic stenosis is a congenital cardiac condition, which frequently results in a heart murmur. According to the ABA, bullmastiffs live with mild and moderate cases just fine, but more severe cases prompt sudden death. 

Deep-chested big dogs like bullmastiffs develop bloat quickly, and it’s a life-threatening condition that requires emergency surgery so a veterinarian can untwist the stomach, among other things. The ABA states that to help lessen the chances of bloat in bullmastiffs, pet parents should serve small but frequent meals, reduce the pace of eating so not so much air is swallowed, and control drinking habits so too much water isn’t consumed at once.

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. Since the act was a criminal offense, most landowners want to capture poachers, not mangle them, so the goal was to create a dog that was quick and assertive, but also even-tempered. 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 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.