Stuart Fitzgerald
Dr Stuart Fitzgerald (MVB MANZCVS, University College Dublin)
Photo of adult Bullmastiff

The Bullmastiff was developed relatively recently as a guard dog and deterrent for would-be thieves and poachers. Despite this history, a well-socialised and trained Bullmastiff is a truly pleasant companion, with an easy-going disposition. The breed does not require a huge amount of exercise, and being a utilitarian dog, they can do very well with apartment living, in spite of their considerable bulk.

Bullmastiffs are affectionate by nature with their families, and generally make very good pets for even young children. As with any large breed, it is important to lay the groundwork for good behaviour in puppyhood, and with kind and persistent training, most become very biddable adults. They possess a short hair coat which does not require a lot of work, although they do shed. Another factor to consider in caring for a Bullmastiff is the copious amounts of drool which they produce, and which can be an issue for some owners. Although they will happily spend time outdoors, close contact with the owners is very important, and most will only thrive emotionally when spending time indoors with the family.

They are natural guardians, and as well as providing an obvious visual deterrent, will stand and fight in order to protect their families when needed. However, in the absence of a clear threat, most are aloof rather than aggressive towards strangers. Being derived from other very large mastiffs, the breed does not have a very long life expectancy, averaging between 7 and 8 years.

About & History

The Bullmastiff’s colloquial name of the ‘Gamekeeper’s Night Dog’ gives a clue to its origin. From the mid-nineteenth century, demand from the landed gentry for a fearsome guard dog to protect their estates had grown. This led to the cross-breeding of Mastiffs (too placid for the role) and the now-extinct Old English Bulldog (which had many of the desired personality traits without the physical stature) to produce the Bullmastiff. Early studies of the breed in the twentieth century indicated that the breed at that point owed approximately 60% of its genetic make-up to the Mastiff, with the Bulldog contributing the remaining 40%.

The Bullmastiff became renowned for its power, speed, courage and ferocity in tackling poachers and intruders. Darker coat colours, particularly brindle, were encouraged to aid in camouflage, and for such a large dog, the breed is remarkably quiet and stealthy. Given its power, consideration and effort was also devoted to developing a dog with a loyal and obedient attitude towards its handler. The demand for the Bullmastiff in its original role demised over the passing of the following hundred years, but as it was much-admired, it found a new place as a companion and guard dog.

It was recognised by the UK Kennel Club in 1924, after the gene pool had stabilised, and cross-breeding was no longer contributing to the breed’s development, and was subsequently awarded entry to the American Kennel Club registry in 1933. The breed remains reasonably popular today, ranking in 48th position in the AKC pedigree chart.


Bullmastiff Large Photo

The Bullmastiff is a well-proportioned powerful dog, without exaggeration or physical impediment. It exudes power and strength, without being overburdened with excess body mass. The breed’s coat is short and reasonably dense, and can be one of a range of colour variations:

  • Brindle
  • Red
  • Fawn

White markings on the chest are common, and accepted by the Kennel Club breed standard, although it is preferred that these markings are not pronounced. The breed has a dark mask around the muzzle and eyes,

The skull is large, with slight wrinkling of the skin of the forehead noticeable when the dog is attentive. The eyes are in proportion to the head, dark and alert, and should convey intelligence and curiosity. The ears are triangular, folding over, medium in size, and set high on the side of the head. The muzzle is broad and should not be overly short, being at least one-third the length of the skull. It is very common for Bullmastiffs to have an undershot jaw, something which can be both comical and vaguely menacing, depending on one’s perspective!

The neck is slightly arched due to its pronounced muscle mass, and is impressively wide. The back is not overly long with no hint of a dip, and with plenty of muscle also. The loins are powerful and wide, and the tail is set high and tapers noticeably. The limbs are moderately well-developed, again in proportion to the frame, with an obvious angulation in the hindlimb, denoting an ability to spring. The Bullmastiff should have an easy, strong stride, without being encumbered by conformation or bulk.

Males of the breed stand 64–69 cm (25–27 in) tall at the withers, weighing 50–59 kg (110–130 lb), while females range in height and weight from 61–66 cm (24–26 in) and 41–50 kg (90–110 lb), respectively.

Character & Temperament

Bullmastiffs can be contradictory characters. Docile, warm and affectionate with those they know, willing to be poked, prodded and pulled by children, yet fearsome and intimidating towards strangers should the need arise. Most are quite placid dogs, and do not pose a threat to people, but it is important to ensure lots of positive socialisation experiences for puppies, as the breed can also be quite emotionally sensitive, and will remember negative experiences for life. They are very intelligent dogs, and can learn to live in a variety of surroundings, but do enjoy time spent cuddling with their humans when the opportunity arises.

As with many breeds, with intelligence comes the potential for mischief, and the Bullmastiff needs to be firmly and persistently educated as to his owner’s desires and what constitutes acceptable behaviour. The breed also has a natural want to please, and once the rules are clear, and a reasonable amount of time devoted to training, they make very biddable and empathetic pets who will equally get on well with other animals in the house.


Photo of Bullmastiff puppy

Bullmastiffs are moderately easy to train; not lacking the ability to learn, the challenge may be to keep them interested during training sessions. They learn best when training is not repetitive, but involves a mixture of techniques. Enrolment in a socialisation course is an excellent first step for a young Bullmastiff pup, as it will teach him to tolerate and respect other people and dogs, and also gives the owner a training foundation on which to build.

The breed enjoys being given a job to do, and despite their size, often make excellent agility dogs. Equally, cart-pulling satisfies an instinctive urge to work, as well as helping young dogs burn off excess energy which could otherwise be spent misbehaving. It is important not to be harsh with the dog during training, as cross words or physical rebuke will be taken to heart and keenly felt. If training is conducted in a calm and fun atmosphere, the Bullmastiff will excel.


The breed is prone to some notable health problems, some of which can manifest earlier than would be expected in other breeds.

Abnormal Dentition

Malocclusion (failure of teeth to articulate normally) and dental overcrowding are relatively common, partly because of the unusual jaw conformation. These problems may only become evident after 5–6 months of age, when the adult teeth have fully erupted. Some dogs may require dental extractions to correct overcrowding.

Cervical Vertebral Malformation

In some dogs, protrusion of intervertebral disc or bone into the spinal canal in the neck can cause signs of neurological dysfunction, such as an unsteady gait – the reason for this also being known as wobbler syndrome. Surgery may be indicated to stabilise the spine and relieve pressure.

Cleft Palate

A condition which may be seen in puppies due to a failure for the two sides of the upper jaw and soft tissues to fuse during foetal development. This can lead to a communication between the mouth and nasal cavity, causing difficulties in swallowing, and sometimes, breathing.

Cranial Cruciate Ligament Rupture

This is the most common cause of hindlimb lameness in the breed. The cranial cruciate ligament is responsible for maintaining stability in the knee joint, and is prone to weakening and tearing in large breed dogs. Surgical repair is necessary to prevent the early onset of osteoarthritis in affected joints.


Demodex mites, present in the skin of normal animals, require constant control by the immune system to prevent infestation. Some Bullmastiffs do not have adequate immune function in this regard, resulting in severe itch, hair loss, and secondary skin infection.


Inward or outward scrolling of the eyelids, respectively. Cause irritation and scarring of the surface of affected eyes. Corrective surgery is usually relatively straightforward.

Gastric Dilatation-Volvulus

GDV, or bloat, is the result of the animal’s stomach rotating around its axis, obstructing outflow of gastric contents and blood, and leading to severe shock, and often death without treatment. It is advisable to feed Bullmastiffs little and often, and to avoid exercise within the hour after feeding.

Hip Dysplasia

Malformation of one or both hip joints is a common finding in young dogs. Affected animals should not be used for breeding, as there is a strong genetic basis to the condition.


Thyroid underactivity due to immune-mediated destruction of thyroid tissue. Treatment with thyroid hormone is usually very effective in controlling the signs of alopecia, weight gain, lethargy, and infertility.


This is a common malignancy, which the Bullmastiff is particularly prone to developing. May be noticed by owners as multiple hard lumps under the skin, or may also simply cause initial signs of weight loss and lethargy.

Retinal Dysplasia

A failure in the development of the nerve cells of the retina (the structure at the back of the eye responsible for vision). May be difficult to detect in young pups, but signs of visual impairment are usually noticeable once puppies become mobile.

Progressive Retinal Atrophy

A major problem in many pedigree breeds, this condition results in blindness due to death of retinal cells. Can affect quite young dogs (from 4 years old).

Screw Tail

An excessively twisted tail can cause discomfort and fold dermatitis at the tail base. May require surgery to amputate the tail if severe.

Sub Aortic Stenosis

An abnormal stricture in the major blood vessel leaving the left side of the heart, which may be clinically silent, or can cause significant functional impairment. A ‘murmur’ will be audible on examination with a stethoscope.

Vaginal Hyperplasia

Common in Bullmastiff bitches during oestrus, when the effects of sex hormones cause swelling and protrusion of the vaginal lining. These signs regress over the following few weeks, but care may need to be taken to avoid the dog self-traumatising the vaginal tissue.

Exercise and Activity Levels

Bullmastiffs do not demand too much from their owners in terms of exercise. With between 30 and 60 minutes of lead-walking per day, most will be happy to spend the rest of their time relaxing. They do, of course, enjoy more vigorous exercise when possible, and this may be more important for those kept as indoor-only dogs in apartments. Some may suffer in the warmest of weather, and, during the summer months, it is advisable to keep exercise to early morning or late evening.


The Bullmastiff’s coat is short but quite dense, and sheds a moderate amount of hair, particularly if spending a lot of time indoors. Weekly brushing to lift and remove dead hairs is generally all that is required to keep the coat and skin in good condition. Bathing using an appropriate dog shampoo can be carried out when needed, but should rarely be necessary. Wiping occasionally with a damp cloth will help to remove most dusty and dry materials from the hair.

Unless doing a lot of walking on paved surfaces, the breed’s thick nails can grow quite long. If they can be heard to ‘click’ on indoor floors, then clipping is necessary. To do so requires a very good set of clippers and a calm approach. Bullmastiffs can become panicky about the nail-clipping process should they have a negative experience, and it may be worth asking a professional to carry put the task.

Because of the undershot jaw, some dogs will be prone to dental tartar build-up, and so teeth should be brushed, ideally on a daily basis.

Famous Bullmastiff

Some of the more public figures within the breed have been:

  • Brutus, owned by Bob Dylan
  • Butkus, the suitably manly companion of Sylvester Stallone
  • Swagger, the mascot of NFL team, the Cleveland Browns


Having originated in the relatively recent past as a crossbreed itself, the Bullmastiff has also been crossed with other pedigrees:

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