The Bullmastiff is formidable in size and personality. A cross between Mastiffs and Bulldogs, the breed was developed by English gamekeepers in the mid 1800s to keep dangerous poachers at bay. This ancestral mix gives the Bullmastiff her powerful build and slightly flattened muzzle. Despite her intimidating appearance, she is loving, gentle, and devoted to her family members. Bullmastiffs are also strong-willed and stubborn. This breed requires owners who aren't easily intimidated and have time for ongoing training.

Other Names

Bullmastiffs have also been called Bullies and the Gamekeeper's Night Dog.

Physical Description


Bullmastiffs have short, smooth coats that offer protection from inclement weather. The coat colors are red, fawn, or brindle.


Average Height: 24-27 inches


Male: 110-130 pounds

Female: 100-120 pounds

Breed Standard & History

The Bullmastiff is a powerfully built dog with an alert, intelligent expression. She has a square, solid frame and muscular, long legs in proportion to her body. Her gait is smooth and capable of great swiftness. A Bullmastiff has a slightly flattened face from the Bulldog side of her family tree. The skin of her face is wrinkled, and the fur on her muzzle and ears is usually darker than the fur on her body.

The job of gamekeepers in 19th century England was a dangerous one because poachers would become violent to escape capture. Bullmastiffs were developed with the bravery and tenacity of a bulldog and the power of a mastiff. Their job was to track poachers until they were close enough to sprint towards the intruders, knock them down, and hold them until the gamekeeper arrived, earning them the moniker, 'Gamekeeper's Night Dog.' The breed's keen eye and strength soon made them popular as watchdogs beyond large estates, and their sweet loyalty made them appealing as companion dogs.

AKC Breed Category

Working Group


General Temperament

Bullmastiffs are courageous protectors and gentle companions. They are cooperative and willing to please—to a point. Bullies have a stubborn side that should never be indulged or it will become tough to reverse. They are generally quiet and mild, but can be pushy and may become aggressive towards other dogs.

Family Life

Are Bullmastiffs Good with Kids? Bullmastiffs are protective, patient companions for children with whom they're raised, as long as they have been trained and socialized well from an early age.

(Note: Every dog has a unique personality and distinct life experiences that affect her disposition. As a rule, adults should always supervise playdates between kids and their four-legged friends.)

Are Bullmastiffs Good with Other Pets? Bullmastiffs don't make great housemates for other pets. Their prey drive is very high, which makes them dangerous for cats. They are also prone to aggression towards other dogs, especially males.


Bullmastiffs are highly protective of their turf, and especially of their families.

Are Bullmastiffs Good Guard Dogs? Originally bred to protect game from poachers in the English countryside, Bullmastiffs make excellent guard dogs. They are attentive to the perimeter of their property and will charge at anyone they feel poses a threat to their families. Their sheer size can intimidate intruders, and even some welcome visitors.

Energy Levels

These athletic animals do not have an excess of energy. They need daily exercise, but keeping them healthy does not require vigorous, lengthy activity.

Specific Concerns

  • The Bullmastiff may be aggressive with other animals, particularly if she is not socialized early.
  • She is prone to heat-related illnesses.
  • She is stubborn and independent.
  • She drools copiously, so furniture protectors will be key to a clean home.



Bullmastiffs are indoor dogs. They cannot stay outside for long periods of time, especially in the heat and humidity because they are prone to heat exhaustion. They are excessive droolers, so it's wise to have a slobber towel handy at all times. They also shed, but regular brushing will keep stray fur under control.


A securely enclosed outdoor area is important for Bullmastiffs because they are inclined to roam. They need ample opportunity for moderate exercise, but should not be outside when it is very hot because of the risk of heat-related illnesses.


Bullmastiffs need moderate amounts of exercise each day. A few mid-length walks and some low-key play sessions will keep her fit. Watch your Bullmastiff for signs of heat exhaustion during any exercise.


Bullmastiffs are sprinters and run out of steam quickly during vigorous play. They have the stamina for extended moderate activity, such as walking or easy-going play.

Activity distance rating


Adult Bullmastiffs require about three to four cups of quality dry dog food each day, split between two meals. The amount will vary depending upon the size, weight, activity level, and age of your dog. Talk with your veterinarian about an optimal diet plan.

Alone Time

Bullmastiffs can manage moderate periods of time alone gracefully. If you spend the entire day out of the house for work, however, your Bullie will need a walk and engagement to keep her from getting bored.

Health and Grooming

Life Expectancy

8-10 years


Bullmastiffs require minimal grooming. Brushing her a few times a week and bathing her once a month will keep your Bullie's coat healthy and clean. Clip her toenails at least once a month, and check and gently clean her ears with a mild cleanser once a week to prevent wax buildup, which can cause infections. Brush her teeth daily.

Common Health Issues

Bullmastiffs have a short life span and may present some breed-specific health concerns, including:

  • Canine cancers
  • Hip and elbow dysplasia
  • Brachycephalic
  • Gastric torsion
  • Cardiomyopathy
  • Hypothyroidism
  • Subaortic stenosis

You can minimize serious health concerns in a Bullmastiff by purchasing from a reputable breeder who engages in responsible breeding practices, and through screening for common diseases and conditions.



An intelligent breed, Bullmastiffs pick up on basic obedience training quickly. They have willful personalities, however, and require consistent training that is gentle yet firm.

Advanced Training

Bullmastiffs should be trained beyond the basics because of their size, stubbornness, and protectiveness. Owners should have unfailing control over this breed when interacting with strange people and dogs, or if they get loose. Agility training and dog sports are good for the slow-moving Bullmastiff, though she may not be keen to participate.

Sporting Dog Training

Bullmastiffs are not good candidates for sporting dog training.

Breed FAQ

Here are a few commonly asked questions about Bullmastiffs.

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No. Bullmastiffs shed and, as a result, leave pet dander in your home. Dander is the cause of most pet-related allergies.

As brachycephalic dogs, Bullmastiffs are not built for long swims because it is difficult for them to keep their snouts above water. To cool off, a Bullmastiff may enjoy splashing around in water sufficiently shallow that she can't immerse her head.