What Is a Bullmastiff?

Fearless yet gentle, this giant is an ideal guardian and companion.
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To an assailant or burglar, the bullmastiff is a tough, ferocious guard dog who will protect his family and defend his home. But to his human family members, he's a gentle giant who snorts and slobbers while lovingly leaning against his favorite person. While the English mastiff is one of the oldest dog breeds in his native country of Britain, it was not until the 1800s that the smaller bullmastiff was developed to create a formidable guard dog.

Two Breeds Come Together

During the 1800s, English gamekeepers faced dangerous challenges when poachers encroached on their preserves. To fend off the poachers, the gamekeepers needed a dog that was large, fast and agile enough to overtake the intruders. They also needed a dog that was aggressive enough to attack on command, pin down the poacher and hold him firmly in place without inflicting extreme bodily harm. The bulldog was too ferocious and too small, and the mastiff was too slow. In 1860, the gamekeeper's ideal guard dog was realized when the bullmastiff was created by crossing the two breeds, creating a dog for both protection and companionship. The American Kennel Club first recognized the bullmastiff as a member of the working group in 1934.

Size, Color and Other Physical Traits

The blueprint for the bullmastiff was to create a dog that would be 60 percent mastiff and 40 percent bulldog. The bullmastiff grows to a height of 24 to 27 inches at the shoulder. This heavyweight breed weighs in at 100 to 130 pounds. Bullmastiffs are clad in short, thick coats to protect against the elements. The coat may be red, fawn or brindle in color. Bullmastiffs have black masks, and their dark eyes convey an alert and keen expression. They have large, substantial, powerful bodies and wide, square heads. Their tails are long and tapered, and their ears appear as V-shaped flaps that hang downward to the cheekbones.

Temperament and Habits

The bullmastiff temperament is alert and courageous. He has no fear when faced with confrontation with an unwelcome intruder in his domain, making him an excellent candidate for a guard dog. Toward family members, he is docile and loving. Bullmastiffs are patient and tolerant, and do well with children. They must be socialized from the earliest age to get along with other household pets and to accept meeting new people. Bullmastiffs are intelligent and trainable, but they are strong-willed and independent -- not a breed for a first-time or uninvolved dog owner. Bullmastiffs enjoy being with their owners. They are quieter and have less energy than one would expect from a large breed, and adapt well to apartment living. Be prepared for a noisy and sloppy roommate. Bullmastiffs snort, snore and drool, and they can be messy eaters.

Health Concerns

Hip dysplasia, elbow dysplasia, hypothyroidism, cardiomyopathy, sub-aortic stenosis and heart murmurs are some of the health conditions to be aware of in the bullmastiff. Skin allergies and eye conditions, including entropion and progressive retinal atrophy, have also been noted. The more common cancers to occur in bullmastiffs include osteosarcoma, lymphoma, hemangiosarcoma and mast cell tumors. The breed is also prone to anterior cruciate ligament teats and gastric torsion, or bloat. Bullmastiffs have a low tolerance for extreme heat, so summer exercise should be limited in duration and restricted to the coolest hours of the day. The life expectancy for a bullmastiff is 8 to 10 years.