Bullmastiff

Personality

Fearless at work and docile at home, the Bullmastiff is a gentle giant with a serious job description. The AKC calls the breed loyal, affectionate and brave, and says the confident, alert expression makes it a world-class protector. In practice, most Bullmastiffs are calm house dogs that keep an eye on things rather than make a fuss.

PetMD describes them as affectionate and docile with family, including children, and reserved with new people and animals unless they have been socialized. They are quiet dogs that bark mainly to alert you.

They can also be strong-willed. The AKC says the breed can be quite strong-willed and that owners need to establish rules and routines early. A 120-pound dog without manners is a serious problem, not a quirk.

Mostly, Bullmastiffs want to be near their people. The AKC says they are biddable and reliable, but as with any large guarding dog, early training and socialization are essential while the puppy is still small enough to control.

History

The Bullmastiff's nickname, "the Gamekeeper's Night Dog," sums up its past. In the mid- to late 1800s, English estates and game preserves were targets for poachers, and the penalties were harsh enough that some poachers would risk a fight with a gamekeeper rather than be caught. Gamekeepers responded by breeding dogs big, quick and brave enough to pursue and pin a man at night.

The AKC says breeders eventually settled on crossing Mastiffs with Bulldogs, in roughly 60 percent Mastiff to 40 percent Bulldog. The result was a dog smart enough to work on command, steady enough to hold an intruder without mauling him, and large enough to intimidate. It was an old-style Bulldog, not today's flat-faced companion, that was used in the cross.

Competition among gamekeepers led to exhibitions, and from there the Bullmastiff moved into the show ring. The English Kennel Club accepted the breed in 1924, and the AKC followed in the early 1930s. In 1928, the De Beers company imported Bullmastiffs to guard its diamond mines in South Africa. Today, the AKC says, the primary job of most Bullmastiffs is as a dependable family dog.

Appearance, coat & colors

The Bullmastiff is not quite as large as its cousin the Mastiff, but it is still a lot of dog. The AKC lists males at 25 to 27 in (64 to 69 cm) and 110 to 130 lb (50 to 59 kg), and females at 24 to 26 in (61 to 66 cm) and 100 to 120 lb (45 to 54 kg).

The large, broad head conveys the breed's essence. The AKC points to the dark eyes, high-set V-shaped ears and broad, deep muzzle as the features that signal intelligence, alertness and confidence. The body is powerful, with heavy bone, and the AKC says breeders aim to avoid "overdone" dogs that are too heavy to do the job of a working guardian.

The short, dense coat comes in fawn, red or brindle in various shades. The breed standard prefers a dark muzzle and allows only a very small white spot on the chest.

The overall impression is of strength with sound structure, not mere bulk. A good Bullmastiff should look balanced and athletic for its size, and ready to move.

Training

Early training is critical with a Bullmastiff. The AKC says the breed can be quite strong-willed and that dogs and owners benefit when rules and routines are set in puppyhood and kept up as the dog grows. PetMD calls the breed very intelligent and quick to learn, but says it can become strong-willed as it matures and suggests the breed suits experienced owners.

Enroll in a puppy class as soon as your vet allows. The AKC says classes expose puppies to other dogs and give owners access to help. Socialization should continue throughout the first years, with calm, positive exposure to people, places and other animals.

Use rewards and consistency. Short sessions, treats and praise work better than force with a dog that outweighs most adults. Teach basics early: sit, down, wait, leave it and loose-leash walking. A giant that pulls is hard to manage.

Bullmastiffs can excel at more than guarding. The AKC says they can do well in agility, obedience, rally, scent work and tracking, so training can be part of the lifelong bond with your dog.

Exercise

Bullmastiffs enjoy daily exercise, but they are not endurance athletes. The AKC says some are more sedentary and others very active, and that moderate exercise should be encouraged. Brisk walks and outdoor play are favorites. The AKC adds that the breed is not an ideal running partner but is a great walking companion, and PetMD notes that the breed lacks the stamina for long-distance running.

Puppies need extra care. The AKC says not to overexercise them during rapid growth. Ask your vet how much activity is right at each stage, and avoid long runs and repeated jumping while the joints are developing.

A secure fence is a must. The AKC says fencing is critical so the dog stays safely contained and so strangers and unfamiliar animals cannot intrude on its territory. Our guide to how much exercise a dog needs helps you match activity to your dog's age.

Exercise is discouraged right before and after meals because of the risk of bloat. Keep walks on the calm side in hot weather.

Grooming

Bullmastiffs are easy to groom. The AKC expects seasonal shedding, and says unusual hair loss should be noted as a possible problem. Frequent brushing keeps the shedding manageable, and the dog should be bathed as needed. PetMD suggests brushing about once a month, though more often during heavy shedding makes sense.

Watch the skin and coat. The AKC says to check that dryness or oiliness is not developing, because these can relate to diet and sometimes to allergies. A balanced diet and healthy environment matter most for coat health.

Drool is part of the package. PetMD says the jowls may need daily wiping, and the eyes and ears need regular attention. The ears, in particular, should be checked for debris or redness. Allergy-related ear infections and tear staining can occur.

Trim nails often, because large dogs with overgrown nails walk awkwardly. Brush teeth regularly. Professional grooming is generally not needed.

Feeding

Growth is the big feeding issue. The AKC says most breeders advise feeding either an adult dog food or a large-breed puppy food so that growth stays slow and steady. Several small meals work best for puppies, and two meals daily are a good routine for adults, so the dog does not have to digest too much at once. Keep Bullmastiffs lean, especially as puppies, because rapid growth can tax their systems.

Because of the risk of bloat, the AKC discourages exercise immediately before and after meals. VCA lists eating one large meal a day, eating quickly and exercising after a big meal among bloat risk factors. A slow-feeder bowl can help a dog that gulps.

Our dog food calculator can give an estimate for adults, but your vet should guide puppy feeding. Measure meals, count treats and avoid free-feeding. You should be able to feel the ribs under a thin layer of padding.

Keep fresh water available and ask your vet before using supplements.

Health

The AKC calls Bullmastiffs generally healthy, but they are a large breed with a short life: the AKC lists a life expectancy of 7 to 9 years. PetMD attributes that to the breed's size.

PetMD lists several conditions to watch: hip and elbow dysplasia, which are inherited joint problems; entropion, in which the eyelid rolls inward and irritates the eye; progressive retinal atrophy; dilated cardiomyopathy, a weakened heart muscle; subaortic stenosis, an inherited heart defect that appears in the first year of life; lymphoma, a cancer of the lymph nodes; and bloat. The AKC also mentions hypothyroidism and says Bullmastiffs, like many dogs, can develop cancer.

Bloat and gastric dilatation-volvulus (GDV) are emergencies. A swollen belly, unproductive retching, restlessness or collapse means you should call your vet or an emergency clinic right away. PetMD suggests asking your vet about a preventive gastropexy. Our page on bloat and GDV explains more.

Screening for breeders includes hip, elbow, cardiac, eye and thyroid exams.

Health conditions to know about

• Hip and elbow dysplasia — Inherited joint malformations common in large breeds; breeders should screen for them.
• Bloat (GDV) — Life-threatening stomach twisting in deep-chested dogs; needs emergency care.
• Heart disease — Includes dilated cardiomyopathy and inherited subaortic stenosis; breeders should do cardiac exams.
• Cancer — Lymphoma and other cancers occur in the breed; report new lumps or weight loss early.
• Entropion — An inward-rolling eyelid that irritates the eye and needs surgery.

Health tests to ask a breeder about

• Hip evaluation
• Elbow evaluation
• Cardiac exam
• Eye exam by a veterinary ophthalmologist
• Thyroid evaluation

Written from veterinary sources by the Pawsplained editorial team. Not yet reviewed by a veterinarian; this is general information, not a diagnosis or treatment plan. Updated Oct 30, 2026. Editorial policy

Living with a Bullmastiff

Bullmastiffs are big dogs with big space needs, but they are not hyperactive. They like to be near their families, and PetMD says they may not do well in apartments or small homes. A house with a securely fenced yard is ideal.

At home they are typically calm. PetMD describes them as quiet and mostly barking to alert. The AKC rates the breed at the top of its scale as a watchdog.

With children, Bullmastiffs are often gentle, but size is a hazard: a dog that can knock over a toddler just by leaning needs supervision. Visitors and children who are not family should be introduced calmly.

Expect some drool and a dog that sleeps in the way. In hot weather, give shade and water, and keep exercise light.

Puppies, breeders & rescue

A Bullmastiff puppy will grow into a 100-pound-plus dog, so choose carefully. Prices vary widely, and a high price is not a guarantee of health. Ask for proof of testing: the AKC lists hip, elbow, cardiac, eye and thyroid evaluations as recommended screening, and notes that responsible breeders support the American Bullmastiff Association's health and research committee.

Look for breeders who strive to match the breed standard and avoid overdone dogs, as the AKC puts it, with sound structure and temperaments you can see for yourself. Meet the mother, ask about heart and cancer history in the pedigree, and ask how long relatives lived. A good breeder raises puppies in the home, supplies a written contract and takes the dog back at any age.

Be wary of sellers who offer "rare" colors or always have puppies.

Adults from rescue can be a great choice for experienced owners. Ask about the dog's behavior with strangers and other dogs. Our breed selector can help you compare large breeds before you commit.