What to Know About Bullmastiffs

Medically Reviewed by Amy Flowers, DVM on May 01, 2022
6 min read

Bullmastiffs are domestic guard dogs from the 19th century. Gamekeepers used these dogs to protect estates. They are a mix of the English Mastiff and Old English Bulldog, later recognized as purebred dogs by the Kennel Club. They have similar characteristics to Molosser dogs.

Bullmastiffs have a solid build with a short muzzle. They are friendly and trustworthy dogs but require training from their owners to behave well in society. Bullmastiffs are known for their mild nature and rarely bark.

Bullmastiffs share the characteristics of a bulldog and a mastiff. So how big do bullmastiffs get? Males have a standing height of 25 to 27 inches at the shoulder, which is not even close to mastiff height. Female bullmastiffs are 24 to 26 inches tall. 

Male bullmastiffs weigh around 110 to 130 pounds, and females are 100 to 120 pounds — an excellent size for big, strong guard dogs. The average bullmastiff lifespan is 7 to 9 years.


Bullmastiffs have a large, broad head with dark eyes, deep muzzle, and high V-shaped ears. Their coats are red, fawn, or brindle. They are short and shed moderately, so you only have to groom them about once a month.


Bullmastiffs are affectionate with their owners and with young children. They are moderately playful and open to strangers, but their sharp sense of vigilance makes them great watchdogs.

Bullmastiffs can be long-term companions, but they need proper training and socialization practice when they are small. Nevertheless, they have an excellent trainability level and lots of energy. 

Owners should expect to be playing with their bullmastiff all day long. They have high mental stimulation needs and have to keep busy.

Bullmastiffs' coats are small, so they shed seasonally. Pet owners need to be careful about the diet of bullmastiffs to maintain their coat health. A bullmastiff's coat also requires proper bathing and frequent grooming to stay managed. 

Owners must also observe the oil and dryness levels of the dog's skin and coat. If there is an imbalance, it might indicate allergies or other health conditions.


Bullmastiffs are highly energetic and active dogs, so they enjoy daily exercise and activities like brisk walks and outdoor games. Some bullmastiffs can be more sedentary, but they still need exercise to stay healthy. 

Owners should provide secure fencing to keep bullmastiffs safe at home. Proper fencing keeps the dog away from strangers. 

Bullmastiffs need a lot of mental stimulation, but they shouldn't be overexercised. Someone looking for a fast-paced canine friend may not find a bullmastiff to be the best fit. A bullmastiff can be the perfect walking partner, though.


As for any watchdog, socialization and training are essential for bullmastiffs when they are small. This dog breed is strong-willed, determined, and intelligent, so they should do well with a training regimen that begins in puppyhood. 

Owners must set strict rules and schedules for the bullmastiff puppy and adhere to them as they grow older. Puppy training classes can also foster a bullmastiff's interaction and communication with other dogs. 

Bullmastiffs excel in obedience and agility, making them learn quite fast.


Many bullmastiff breeders feed adult dog food to puppies to make them grow slowly. Some also opt for large-breed puppy food for bullmastiffs. 

It's better to serve a bullmastiff small meals in their puppyhood. Then, owners can increase the meal portion and move to two feedings a day as the dog grows. This prevents the bullmastiff from struggling to digest too much food at once. 

Attention to the nutritional needs of bullmastiffs also prevents bloating caused by excessive eating. Bullmastiffs are lean, so their body weight and size must stay balanced to stay safe from several health issues.

Bullmastiffs need to be mentally and physically stable to be guard dogs. It's recommended to take them to a vet now and then for checkups and routine tests. 

Bullmastiffs are generally at a greater risk of cardiac, hip, elbow, and thyroid issues. They can also develop eye issues and cancer. Some dogs can also develop bloating conditions, such as  gastric dilatation and volvulus (GDV), in which the animal's stomach fills with air and twists. GDV restricts the stomach's blood from returning to the heart and other areas of the dog's body. It is a life-threatening condition. 

Dog owners must be well aware of the common bullmastiff health issues and their symptoms. Several hereditary and developed health problems may occur in this dog breed, including:

Hip dysplasia 

This is a common skeletal condition in large-breed dogs. It affects 24.5% of bullmastiffs worldwide. In this condition, the ball and the socket of the hip joint don't develop or fit properly with each other. This results in the bones rubbing and grinding instead of sliding smoothly. 

Hip dysplasia can deteriorate the dog's condition over time, resulting in the eventual loss of the joint. The common symptoms of hip dysplasia in bullmastiffs are:

  • Decreased activity
  • Difficulty jumping, running, or climbing stairs
  • Loss of thigh muscle mass
  • Enlargement of the shoulder muscles 
  • Pain 
  • Stiffness

Elbow dysplasia 

This is abnormal development of the elbow joint in young and large dogs. The bone and cartilage of the elbow grow unusually, resulting in joint stress. This condition affects 13.8% of bullmastiffs.

A dog's elbow joint has three bones: the ulna, radius, and humerus. Any failure in the position of any of these bones can result in irregular weight distribution on the joint. 

The common symptoms of this bullmastiff health issue are pain, lameness, and arthritis.


This is a condition when a dog's eyelid turns inward, resulting in rubbing between the eyelash and the cornea (the part that covers the iris). Entropion is a common eye issue in bullmastiffs that can be either developed or inherited. 

The symptoms of entropion in dogs are:

  • An inverted eyelid 
  • Excessive tear production 
  • Staining    
  • Eye discharge 
  • Redness in the eye
  • Squinting


This is a common endocrine disorder in dogs that results in an underactive thyroid function. Hypothyroidism slows down several critical bodily systems in dogs. The leading cause of this condition is low serum thyroid hormone concentrations. It needs to be managed daily with thyroid hormone replacement.

The common symptoms of hypothyroidism are:

  • Fatigue
  • Weight gain
  • Haircoat changes
  • Unusual skin


Lymphoma is a broad term that includes several cancers originating from the lymphocytes. Lymphocytes are white blood cells that strengthen the immune system to fight infection. These cells are present in any immune system organ, including the spleen, bone marrow, and lymph nodes.

Common symptoms of lymphoma in dogs are:

  • Swelling
  • Lethargy
  • Fever
  • Weakness 
  • Weight loss
  • Diarrhea
  • Increased urination
  • Anorexia 

Progressive retinal atrophy (PRA)

This is a group of degenerative diseases that affect the vision of dogs. They strike the photoreceptor cells and deteriorate them over time. The dog may become completely blind if they don't get proper treatment.

Common symptoms of this condition are:

  • Night blindness
  • Clumsiness
  • Dilated pupils


This is a common condition in older dogs, affecting the hips, legs, and back. Over time, the dog with arthritis struggles to walk, run, or climb properly and makes painful movements. The condition can be hereditary or developed later in the dog's life. 

With proper treatment and exercise, this condition can be treated. The common symptoms of arthritis in dogs are:

  • Difficulty in standing up from a lying position
  • Struggling in going upstairs 
  • Painful movement and jumping 
  • Taking narrow stances in the rear limbs
  • Shedding muscles in the rear limbs
  • Lethargy

Bullmastiffs are not as friendly as other dogs. In their puppyhood, they are reserved and may feel intimidated when a stranger touches or comes close to them. This is why owners need to start socialization and training exercises early.

Bullmastiffs are generally quiet dogs. They don't often bark, so their owners need to be alert for any changes in their behavior. If the dog is barking more than usual, the owner should consult a vet as soon as possible.

Bullmastiffs are highly adaptable and protective. They require minimal grooming, so it's easy to live with one.

English gamekeepers bred bullmastiffs in the 19th century to protect estates. They are also called "Gamekeeper's Night Dog." A bullmastiff is a cross between an Old English Bulldog and English Mastiff. This ensured that the resulting dog breed would be enormous, powerful, and loyal.

Bullmastiffs were recognized as a breed by the English Kennel Club in 1924. The American Kennel Club recognized the breed in 1933 and approved the first breed standard in 1935. 

Bullmastiffs used to pull things in their early days, but now they are solely domestic guard dogs.