B
Species Profile

Bullmastiff

Canis lupus familiaris

Silent strength, steadfast guardian.
iStock.com/Wavetop

Bullmastiff Distribution

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Origin Location

This map shows the native origin of the Bullmastiff. As a domesticated species, they are now found worldwide.

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Size Comparison

Human 5'8"
Bullmastiff 2 ft 1 in

Bullmastiff stands at 37% of average human height.

Mastiff, English Culture, Bull Mastiff, British Culture, Animal

At a Glance

Domesticated
Also Known As Bull Mastiff, Gamekeeper's Night Dog, Gamekeeper's Dog, Bullie
Diet Omnivore
Activity Diurnal+
Lifespan 8 years
Weight 59 lbs
Status Not Evaluated
Did You Know?

The Bullmastiff was developed in late-1800s England as the "Gamekeeper's Night Dog" to help deter and catch poachers on large estates.

Scientific Classification

The Bullmastiff is a large, short-coated domestic dog breed developed as a guardian/estate dog, historically associated with mastiff-type dogs. It is a robust, powerfully built canid used primarily as a companion and watchdog/guardian breed.

Kingdom
Animalia
Phylum
Chordata
Class
Mammalia
Order
Carnivora
Family
Canidae
Genus
Canis
Species
Canis lupus familiaris

Distinguishing Features

  • Large, muscular, mastiff-type build with broad head and short muzzle
  • Short, dense coat (commonly fawn, red, or brindle) often with a dark facial mask
  • Drop ears and a relatively short, strong neck and back
  • Typically calm, confident demeanor; historically selected for guarding

Physical Measurements

Males and females differ in size

Height
♂ 2 ft 2 in (2 ft 1 in – 2 ft 3 in)
♀ 2 ft 1 in (2 ft – 2 ft 2 in)
Length
♂ 4 ft (3 ft 7 in – 4 ft 5 in)
Weight
♂ 120 lbs (110 lbs – 130 lbs)
♀ 100 lbs (90 lbs – 110 lbs)
Tail Length
♂ 1 ft 2 in (12 in – 1 ft 4 in)
♀ 12 in (10 in – 1 ft 2 in)
Top Speed
25 mph
Slower, short bursts only

Appearance

Primary Colors
Secondary Colors
Skin Type Skin fairly thick with some looseness around the neck/throat, forming a protective ruff. Short, dense double coat. Facial wrinkles are common and can get mild skin-fold irritation if not kept clean and dry.
Distinctive Features
  • Domestic dog breed (Canis lupus familiaris) selectively developed for estate guarding; differs from the base domestic dog population by its consistently mastiff-type morphology: heavy bone, compact power, broad skull, and short coat.
  • Large, robust, powerfully built guardian with substantial chest and neck; historically bred to deter and hold intruders rather than to herd or hunt at distance.
  • Head: very broad with a short, square muzzle (brachycephalic tendency but not as extreme as some toy brachy breeds); pronounced stop; strong jaw; black mask is breed-typical.
  • Body: muscular, deep-chested, and comparatively compact for its mass (less towering and generally lighter than the English Mastiff; more square/athletic outline than many giant mastiffs).
  • Coat: short, weather-resistant, and close to the body; sheds seasonally and benefits from weekly brushing to reduce loose hair.
  • Temperament-linked appearance/carry: alert, steady, confident stance; tends to be reserved with strangers-an expression shaped by its guard-dog selection.
  • Common health concerns tied to build: hip and elbow dysplasia; cranial cruciate ligament injury risk; osteoarthritis as they age.
  • Brachycephalic-related risks (variable by individual): heat intolerance, snoring, and reduced exercise tolerance in hot/humid weather; avoid strenuous activity during heat and provide shade/water.
  • Gastric dilatation-volvulus (bloat) risk typical of large, deep-chested breeds: feed measured meals, avoid heavy exercise right before/after eating, consider slow-feeding strategies if gulping.
  • Cardiac concerns seen in some lines (e.g., subaortic stenosis/cardiomyopathy screening in breeding programs).
  • Cancer predisposition reported in large mastiff-type breeds (e.g., mast cell tumors/osteosarcoma risk); emphasize routine veterinary checks and prompt evaluation of lumps/lameness.
  • Skin/ear care: facial wrinkles and droopy lip areas can trap moisture; clean/dry folds as needed; check ears regularly for irritation/infection.
  • Growth and weight management: slow, controlled growth and lean body condition are important to reduce orthopedic stress; use large-breed puppy diets and avoid excessive jumping on hard surfaces during growth.
  • Exercise needs: moderate, steady conditioning (leash walks, low-impact play) rather than repetitive high-impact activity; mental enrichment supports a guardian breed's calm, stable behavior.
  • Training/handling: early socialization and consistent, reward-based training are essential due to size and protective instincts; secure fencing recommended for a watchful guardian breed.
  • Drooling is common (mastiff-type flews), especially after drinking/eating-normal husbandry includes wiping the mouth and monitoring for skin irritation at lip folds.

Sexual Dimorphism

Males are typically larger and heavier-boned with a broader head and more pronounced neck/forequarter musculature; females are generally slightly smaller with a somewhat more refined (but still powerful) outline. Both sexes share the same coat types and typical mask/brindle patterns.

♂
  • Greater overall mass and height; thicker neck and heavier forequarters.
  • Broader skull and more pronounced head width; often a more imposing 'guardian' silhouette.
  • May show more pronounced facial wrinkle/loose skin around the neck due to heavier build.
♀
  • Slightly smaller frame with a more streamlined, athletic look while retaining mastiff-type substance.
  • Head typically a bit narrower/less blocky than males but still broad relative to many other dog breeds.
  • Often matures a touch earlier in body fill compared to males, though both are slow-maturing large breeds.

Did You Know?

The Bullmastiff was developed in late-1800s England as the "Gamekeeper's Night Dog" to help deter and catch poachers on large estates.

It was created by crossing mastiff-type dogs with Bulldogs, aiming for a strong, agile, brave guardian that could work quietly at night.

Unlike many guard dogs bred to bark constantly, a well-bred Bullmastiff is often watchful and quiet-reacting when it truly matters.

Typical coat colors are fawn, red, or brindle, commonly with a dark "mask" on the face-useful for a serious, intimidating guardian look.

Many Bullmastiffs instinctively block, body-check, or pin a threat rather than repeatedly bite-matching the breed's original "hold and stop" job.

The breed's heavy build and short muzzle make it more heat-sensitive than many athletic working dogs; summer exercise usually needs extra caution.

A famous Bullmastiff named Butkus belonged to Sylvester Stallone and appeared in the film Rocky (1976).

Unique Adaptations

  • Mastiff-type morphology (broad head, powerful neck/forequarters) optimized for strength and close-quarters control rather than distance running-more "stopper" than "chaser" compared with many dogs derived from cursorial hunting lines.
  • Short, dense coat that's easy to maintain and suits an outdoor-to-indoor guardian lifestyle, though it offers less insulation than double-coated working breeds.
  • Guardian temperament selection: steadier nerves and lower reactivity are prized-designed to assess and respond, not to be constantly on edge.
  • High mass-to-height ratio: provides physical presence and pushing power, but also means joints and soft tissues can be stressed if overexercised in puppyhood.
  • Compared with the base species context (domestic dogs overall, and wolves as the ancestral lineage), Bullmastiffs trade endurance and long-distance efficiency for compact power, territorial guardianship, and strong human-focused bonding.

Interesting Behaviors

  • "Lean-and-block" guarding: using body weight to stand between family and a perceived threat, often without vocalizing.
  • Patrolling and checkpoint habits: choosing vantage points (doorways, hallways) to monitor movement and visitors.
  • Close-contact bonding: many prefer to stay near their people, following from room to room despite their large size.
  • Strong deterrent posture: stillness, direct stare, and squared stance can be more common than frantic barking.
  • Mouthing and roughhousing in youth: young Bullmastiffs can be boisterous and need early manners training because of their size.
  • Short-burst play style: quick sprints and wrestling, then a strong "off switch" and desire to rest.

Cultural Significance

Bullmastiffs (Canis lupus familiaris) are tied to British country estates and gamekeepers. They became used as property, industrial, and mining guard dogs. In culture they stand for steady protection and loyal company, big enough to deter trouble, calm as family dogs if trained.

Myths & Legends

The "Gamekeeper's Night Dog" tales: estate lore describes Bullmastiff-type dogs working in darkness, moving quietly beside keepers, then surging forward to stop poachers by bowling them over and holding them until help arrived.

Country-house stories say the Bullmastiff can oddly tell a welcome guest from a stranger. Dogs ignored familiar staff but quietly followed unknown footsteps along hedgerows and garden walls.

The black-mask mystique: in some traditional kennel talk, the dark facial mask was treated as part intimidation, part practical "night-face" that seemed to hide expression until the dog chose to reveal intent.

Early breed-creation stories circulated among keepers framed the Bullmastiff as a deliberate answer to a moral dilemma-"stop the man without mauling him"-fueling a legend of the dog as a controlled protector rather than a brawler.

Modern, widely repeated origin storytelling in breed circles casts the Bullmastiff as the estate's silent sentinel-an heir to mastiff guardianship adapted to a specific Victorian-era threat: organized, armed poaching at night.

Conservation Status

NE Not Evaluated

Has not yet been evaluated against the criteria.

Population Stable

Life Cycle

Birth 7 pups
Lifespan 8 years

Lifespan

In the Wild
7–9 years
In Captivity
6–12 years

Reproduction

Mating System Polygyny
Social Structure Managed Domestic
Breeding Pattern Transient
Fertilization Managed Selective
Birth Type Managed_selective

Bullmastiff (Canis lupus familiaris): In managed breeding, a few males mate with many females (polygyny). Humans pick mates, time breeding, and often help with pregnancy and whelping. Females have about 1–2 heats yearly; pregnancy lasts about 63 days. Other dogs usually do not help raise pups.

Behavior & Ecology

Social Pack Group: 3
Activity Diurnal, Crepuscular, Cathemeral
Diet Omnivore Meat-forward complete dog diet (kibble or fresh) with beef or chicken as the primary protein

Temperament

Calm, steady, and confident; generally lower 'busy' drive than many working breeds, but with strong situational readiness.
Protective/guardian-oriented and naturally territorial; tends to assess before acting (watchful, deliberate), distinguishing the breed from many more openly social domestic dogs.
Affectionate and gentle with familiar family members; can be reserved or suspicious with strangers-early, positive social exposure is a key care requirement to prevent over-guarding or fear-based reactivity.
Moderate trainability: responds best to consistent structure and positive reinforcement; harsh corrections can increase avoidance, shutdown, or defensive behavior. Clear boundaries and impulse-control work are important due to large size/strength.
Moderate dog sociability with common 'selective' tendencies; careful management around intact or same-sex dogs may be needed depending on individual temperament.
Exercise needs are moderate (daily walks, brief training/play). Overexertion in heat is a breed-specific risk; many Bullmastiffs are heat-intolerant and may snore due to a shorter muzzle/large body mass.
Health concerns: hip/elbow dysplasia and cruciate disease (may limit long exercise); gastric dilatation-volvulus (bloat) — feed carefully, avoid intense play after meals; mast cell tumors, osteosarcoma, heart disease, hypothyroidism, skin/ear problems. Regular vet checks, weight control.
Handling/care notes: prone to drooling and may use body-leaning as affiliative contact; needs early leash manners and controlled greetings to prevent accidental knocking-over due to size.

Communication

Deep, low-frequency bark used as an alert/territorial signal Often fewer barks than more vocal breeds, but more intimidating when used
Low growl/rumble or 'grumble' during warning, discomfort, or boundary-setting; context-dependent and should be paired with body-language interpretation.
Snorts, huffs, and heavy breathing; may increase with excitement/heat or exertion.
Whines/soft vocalizations for attention-seeking or mild distress, typically directed at familiar people.
Body blocking/standing between family and a stranger; a hallmark guardian communication that signals ownership of space and protective intent.
Leaning/pushing against people as affiliative contact and reassurance-seeking; common Bullmastiff trait.
Fixed stare, still posture, and controlled approach to evaluate a stimulus; often precedes barking if escalation occurs.
Facial expressions and ear/head carriage changes; jowls and heavy facial skin can make subtle expressions less obvious, so full-body cues (stiffness, weight shift) are important.
Scent marking and investigation (urine marking, ground sniffing) consistent with domestic dog species behavior; may increase around territory boundaries.
Pawing/nudging for attention; mouthy play is usually mild but requires training due to strength and size.

Habitat

Biomes:
Temperate Forest Temperate Grassland Mediterranean Desert Hot Desert Cold Boreal Forest (Taiga) Tundra Alpine Savanna Tropical Dry Forest Tropical Rainforest Wetland Freshwater Marine +8
Terrain:
Plains Hilly Mountainous Coastal Island
Elevation: Up to 9842 ft 6 in

Ecological Role

Domesticated companion/guardian canid; in human environments functions primarily as a deterrent/guardian rather than an active hunter, but can act as an opportunistic mesopredator/scavenger if free-ranging.

Human property and livestock protection through deterrence/guarding behavior Local pest control via opportunistic predation on small mammals Nutrient cycling through waste deposition in managed environments Companionship and social/working roles within human communities

Diet Details

Main Prey:
Small mammals Lagomorphs Ground birds and eggs Carrion
Other Foods:
Grasses Fallen fruit and berries Vegetable matter Starches and grains

Human Interaction

Domestication Status

Domesticated

Bullmastiff (Canis lupus familiaris): a fully domesticated dog breed made in 19th-century Britain by crossing Mastiff-type dogs with Bulldogs to create a gamekeeper's guardian that could stop trespassers with speed, power, and controlled aggression. Bullmastiffs are very large, heavy-boned, short-coated, protective, calmer with strong family bonds, often used as companion-guardians, watchdogs, and sometimes therapy or obedience dogs.

Danger Level

Moderate
  • Large body mass and strength can cause accidental injury (knockdowns, leash pulling) especially with adolescents/elderly.
  • Protective/territorial behavior may escalate to bites if under-socialized, poorly managed, or encouraged to guard inappropriately.
  • Dog aggression can occur; fights may injure bystanders attempting to separate dogs.
  • Higher bite severity potential than small breeds due to size and jaw strength.
  • Risk increases with inadequate training, poor confinement, pain/illness, or irresponsible breeding for unstable temperament.

As a Pet

Suitable as Pet

Legality: Bullmastiff (Canis lupus familiaris) is usually legal as a pet, but local laws, HOAs, or mastiff/dangerous-dog rules may need registration, extra insurance, fencing, leashes or muzzles, or bans. Check local rules.

Care Level: Moderate

Purchase Cost: $1,200 - $3,500
Lifetime Cost: $20,000 - $50,000

Economic Value

Uses:
Companion animal market Working/guardian dog services Breeding and showing Veterinary and preventative care sector Training and behavior services Pet food and supplies
Products:
  • puppy/adult dog sales from breeders and rescues
  • training (basic obedience, leash skills, guardian breed management)
  • veterinary care (routine + breed-associated orthopedic/cardiac screening)
  • pet insurance and liability insurance
  • equipment (strong leashes/harnesses, secure fencing/containment, crates)
  • boarding/daycare (often limited by size/temperament policies)

Relationships

Bullmastiffs were bred by mixing Bulldogs and Mastiffs in England. They were bred to patrol country estates and protect it against poachers. These large dogs with their short muzzles could run quickly enough to catch a poacher and pin him to the ground until a gamekeeper could intervene. They later became popular additions to English dog shows.

Bullmastiff isolated on a white background

Bullmastiffs were bred by mixing Bulldogs and Mastiffs.

History and Origins

The Bullmastiff, which was known as the “Gamekeeper’s Night Dog,” had a significant role in the English aristocracy during the mid-to-late 19th century. Poachers were drawn to the large country estates and game preserves, and many of them risked facing the death penalty if they were caught in the act. To protect against this, gamekeepers were given Bullmastiffs to help guard against poachers. If a poacher was confronted by a gamekeeper, they might opt to fight instead of risking execution.

In order to protect their grounds, gamekeepers began to breed dogs that were powerful, fast, and courageous enough to apprehend an intruder in the darkness. After perfecting the ideal mix of Mastiffs and Bulldogs (60% Mastiff, 40% Bulldog), they created a canine that was intelligent enough to obey orders, gentle enough to detain without hurting, and formidable enough to intimidate any trespassers.

As the popularity of dog shows in England grew, people who had a fondness for Bullmastiffs began to compete and show off the best specimens they had. This eventually led to the Bullmastiff being officially registered with the Kennel Club in 1924. In 1933, the American Kennel Club (AKC) accepted the breed and granted it full recognition.

Bullmastiff laying down with its tongue out

Bullmastiffs were originally bred to protect the animals in large game preserves from poachers.

Size and Weight

Bullmastiffs are a large breed of dog. Males weigh between 110 and 130 pounds and are between 25 and 27 inches tall. Females are slightly smaller, weighing between 100 and 120 pounds, and standing between 24 and 26 inches tall. When they are three months old, Bullmastiff puppies generally weigh between 34 and 43 pounds. A Bullmastiff will be fully grown by the time they are 19 months old.

Common Health Issues

Overall, this is a healthy breed of dog; however, it is prone to a few common health issues. All owners should be aware of these issues and contact their vet if they are concerned.

Since Bullmastiffs have short muzzles, they are more prone to suffering from heatstroke or heat exhaustion. It is important to keep this breed indoors during particularly hot days. During warmer months, try to exercise your Bullmastiff earlier in the morning or in the evening when it is cooler outside.

Hip dysplasia is another health concern that some Bullmastiffs may face, where the thighbone doesn’t fit correctly into the hip bone. The two bones will rub together, causing pain and possibly limping over time. The condition is passed down through the parents, so it is important to find out the history of a dog’s parents from a breeder.

Some Bullmastiffs may also develop hypothyroidism. This condition is caused when there is a deficiency in the dog’s thyroid hormone. It can lead to other problems, such as obesity, lethargy, and infertility. Dogs with hypothyroidism will need to be medicated for the rest of their life.

Temperament and Behavior

This breed has a calm temperament. So, they can be very gentle and loving when they are with their family members whom they know and trust. These traits make them a good pick for families with older children who are on the calmer side.

However, when a Bullmastiff encounters a stranger, their behavior can change to be more suspicious or aggressive. They are independent dogs who are not always easy to train. They do best with experienced owners who know how to be both loving and firm.

How to Take Care of a Bullmastiff

When planning to take care of a Bullmastiff, you should think about this breed’s temperament, nutritional needs, common health concerns, and other unique traits.

The Best Dog Food

Finding healthy and nutritious food that will meet your dog’s needs is important. Therefore, look for large-breed dog food options from reputable companies. Organic dog food is a popular option for owners of breeds like this that can have endocrine/hormonal disorders like hypothyroidism. If you are unsure if a certain food is right for your dog, your veterinarian is always a good resource.

As large-sized dogs, Bullmastiffs eat a lot of food. In fact, most will eat between 3 1/8 and 4 1/8 cups of food each day. However, the exact amount of food your dog will need will depend on his weight, activity level, health concerns, age, and other factors. Splitting the total amount of food that your dog needs into two portions is important in preventing bloat, which can be caused when dogs eat too much at one time. Additionally, you should avoid giving your Bullmastiff vigorous exercise right before or right after they eat because this can also be a cause of bloat.

Puppies should also eat large-breed puppy food because this will help them to grow at a steady rate. They should be fed multiple times throughout the day to accommodate their smaller stomachs. As the puppies get older, the number of times they eat each day can be reduced.

Maintenance and Grooming

During their shedding season, this breed will shed some. However, keeping your dog well-groomed and brushing them can keep the shedding at bay. Be sure to monitor your dog’s skin. If you notice that it is too dry to too oily, it could be an indication that their nutritional needs are not being met or that they have developed an allergy to something.

Training

Because this breed is stubborn, it can be a challenge to train. Many times, these dogs will do best when they are enrolled in an obedience class from a very early age. Making sure your dog is properly trained and socialized from an early age is very important for keeping this breed under control. Early training can also help a Bullmastiff develop a stronger bond with its owner.

Brown and black Bullmastiff

Bullmastiffs were bred to be persistent in tough situations. This can translate to stubbornness during training, so patience is required.

Exercise

Even though some dogs will seem content just lying around or hanging out in the house all day, it is important to make sure this breed gets exercise every day. Taking your dog for a walk and playing with them in a fenced-in backyard are great ways to get them the activity they need.

Puppies

First of all, if you are bringing home a Bullmastiff puppy, you will want to make sure your house is ready for the dog. Puppy-proof your home by removing anything potentially hazardous or that you wouldn’t want to get destroyed by a dog chewing on it.

It will be very important to begin training your dog as soon as you bring them home. Bullmastiffs will be much easier to manage when they are smaller, and the earlier they start the training process, the easier it will be. With this in mind, make sure to find opportunities to socialize your dog as well. This will help them learn how to act around other people and dogs.

Crate training your Bullmastiff can help with potty training. It can also help prevent the puppy from chewing up your things when you are away from the house.

Bullmastiff puppies will need some playtime and exercise. However, you will want to be careful not to overexercise a puppy since they go through a period of rapid growth. That’s because too much exercise can have a negative impact on the development of their bones and muscles.

Bullmastiff puppy in the grass

It is best to start the socialization of puppies early.

With Children

When raised alongside a child, a Bullmastiff can be a good family pet. They are very loyal to the members of their family and can be quite affectionate. It is important to note that Bullmastiffs are not trusting of other people, which could pose a problem when children bring friends home.

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Sources

  1. American Kennel Club / Accessed November 8, 2019
  2. Dog Time / Accessed November 8, 2019
  3. Wikipedia / Accessed November 8, 2019
  4. Hill's / Accessed November 8, 2019
  5. Pet Finder / Accessed November 8, 2019
  6. Adopt-a-Pet / Accessed November 8, 2019
  7. Dogell / Accessed November 8, 2019
  8. Dogell / Accessed November 8, 2019
  9. Dogell / Accessed November 8, 2019
Heather Hall

About the Author

Heather Hall

Heather Hall is a writer at A-Z Animals, where her primary focus is on plants and animals. Heather has been writing and editing since 2012 and holds a Bachelor of Science in Horticulture. As a resident of the Pacific Northwest, Heather enjoys hiking, gardening, and trail running through the mountains with her dogs.

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Bullmastiff FAQs (Frequently Asked Questions)

Purchasing a Bullmastiff from a breed will normally cost between $1,000 and $2,000. If you adopt a Bullmastiff from a shelter or rescue organization, the cost will likely be around $300 for adoption fees and vaccinations. Sadly, many Bullmastiffs get returned to rescue groups because the people who adopt them weren’t ready for the commitment of having this breed. Adopting through a rescue organization can help provide a home to a dog in need.

In addition to paying to adopt or purchase a Bullmastiff, you will need to purchase food and supplies, such as a crate, bed, leash, collar, and food bowls. You will also need money to cover veterinary expenses. The first year you own your dog, be prepared to spend at least $1,000. The following years, you should budget between $500 and $1,000 to cover everything your dog will need.