The mastiff and the bullmastiff are two dog breeds that look similar in appearance. This is not surprising, as the two breeds are closely related and therefore share many common traits. They are still recognized as different breeds, however, and as such have a number of differences both physically and behaviorally.
The mastiff is by far the oldest of the two breeds, dating back to before 55 B.C. Julius Caesar himself, during the Roman invasions of Britain, made mention of the dog. The mastiff was noted as fighting alongside the British defenders and its power and courage stood out, impressing the emperor. The bullmastiff has only been around since about 1860 and is descended from the mastiff. Game keepers needed a dog that would ideally have size, power and could attack on demand to help them against poachers . The mastiff was crossed with the bulldog and the result was the bullmastiff.
The mastiff and bullmastiff are both large, heavily-muscled breeds with a similar physical appearance. The mastiff is larger, growing to 30 inches at the shoulder and up to 160 lbs. The bullmastiff grows to 27 inches at the shoulder and around 133 lbs. In general, the mastiff is broader than the bullmastiff, which has a more slender frame. Like its bulldog ancestors, the bullmastiff was designed for more speed and agility.
Coat and Color
Both breeds have short coats, but the mastiff's is slightly longer and more coarse in texture. The coats are dense to offer protection from cold. Mastiffs come in three main colors: apricot, fawn or brindle. Early in its development the bullmastiff was bred to be dark brindle so it was less visible at night. Today its main coat colors are red, fawn or brindle. For competition purposes both breeds are allowed to have a small chest patch of white.
The temperament of the mastiff is affected by its size. Being so large, it is confident and does not feel the need to show aggression. The breed is generally docile unless it needs to protect its family. It is a calm, dignified breed that is not overly playful, but is good with families due to a gentle nature. The bullmastiff is similar in temperament but is more active, requiring more exercise. Neither breed is generally aggressive, but the bullmastiff is more forceful in defense, knocking down intruders, while mastiffs will tend to corner them.