Bull Mastweiler

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80-120 lbs

The Bull Mastweiler is a very large animal, although it stops just short of being a giant dog. They are a popular cross breed of two powerful and protective animals, the Bullmastiff and the Rottweiler. These dogs are family oriented and are naturally protective, but they are very powerful animals and interactions with smaller children and animals should be closely supervised to prevent injuries due to either abnormal aggression or, more likely, over-exuberant play behaviors. These dogs tend to be quite intelligent and tend to be easy to train, but they can occasionally lean toward the stubborn side, particularly if their training is begun late in their lives. This dog should not be confused with the Mastweiler, a cross between the Mastiff and the Rottweiler, which is typically a larger and more sedentary hybrid.

Companion, Guarding
Date of Origin
Bullmastiff, Rottweiler

Bull Mastweiler Health

Average Size
Height: 24-27 inches Weight: 90-130 lbs
Height: 23-25 inches Weight: 80-120 lbs
Major Concerns
  • Hip Dysplasia
  • Bloat
  • Osteochondritis Dissecans
Minor Concerns
  • Elbow
  • Hypothyroidism
  • Retinal Detachment
Occasional Tests
  • Hip
  • Elbow
  • Thyroid Tests
  • X-Rays
  • Physical Examination

Bull Mastweiler Breed History

The Bull Mastweiler is a popular hybrid, a cross between the Bullmastiff and a Rottweiler, both large and capable dogs that have traditionally been employed as guard dogs and family protection animals. The Bullmastiff is the only guarding breed dog that was developed in England, originally a crossbreed itself, a combination of the English Bulldog and the English Mastiff. They were developed to be guards of the grounds and game on large English estates protecting them from poachers and thieves; the Mastiff was too large and slow for the job, and the Bulldogs of the time didn’t have the restraint needed to prevent mauling of the poachers. The Bullmastiff is a smaller, more agile breed than the Mastiff and a larger and more controlled animal than the Bulldog of the time. The Rottweiler is a German dog, a breed old enough that their full origins are obscured by history, although it is believed by most that they were the descendants of large Roman dogs that drove cattle for the cattlemen and butchers, known as drover dogs, sometime prior to 700 A.D. They were named for the area that they were developed in, a site known as Rottweil for the abundance of red, Roman tiles that were unearthed there. Although their popularity declined during the industrial revolution in the 1800’s, it was rekindled in the 1900’s and they were often employed as police or military animals. The hybrid of the two is less aggressive and more intelligent than the Bullmastiff as well as calmer and less stubborn than the Rottweiler. 

Bull Mastweiler Breed Appearance

This crossbreed produces large to very large canines that are well-muscled with a nearly square appearance, although the dogs are usually slightly longer than they are tall. Their heads are broad and flat, with either round or almond shaped eyes in dark brown that should have an alert expression and their ears are V-shaped or triangular, sit high on the head, and fold down either to the front of the face or to the sides of the head.  They sport short, dense coats which may have a thick undercoat if they lean towards the Rottweiler genetics. The Bull Mastweiler may take its coloration from either side of the family and may come in the traditional Bullmastiff colors of red, fawn, or brindle, as well as mixes of these colors, or they may lean towards the Rottweiler side equation and have black & rust, black & mahogany, or black & tan coloration. Many have black, white, or brindle markings and dark masks are also common.

Bull Mastweiler Breed Maintenance

These dogs are somewhat simple to handle when it comes to grooming as this hybrid’s short coat is quite manageable. Although they require regular brushing with a curry comb or soft bristle brush to control the shedding and distribute their body oils, monthly baths are usually adequate for these dogs. If your dog has inherited the folds or wrinkles commonly seen on Bullmastiffs, care should be taken on a regular basis to ensure that the folds of skin have not trapped any moisture as it can cause skin irritation and a foul odor may develop. They shed moderately year round, although Bull Mastweilers with a double coat tend to shed more heavily than those with a single coat. 

Bull Mastweiler Temperament

The Bull Mastweiler has been developed from two consummate guard dogs, and as such makes a fantastic guard dog as well. Like both parent breeds these dogs are alert and protective animals that are very dedicated to their families. They are generally good with children, although interactions should be closely supervised due to their large size and power; these dogs are playful and may accidentally knock over smaller children, especially if either the child or the dog is young. In some cases, protective may become overprotective and although they are unlikely to intentionally hurt a child, they are more likely than other breeds to cause damage an adult that they consider a threat to a child in their family. In order to prevent aggressive behavior, early socialization and training is crucial. They are an intelligent dog that was bred to work closely with people and although they can show some stubbornness, they tend to pick up on training very quickly, particularly if it is started when they are young. 

Bull Mastweiler Activity Requirements

Although the Rottweiler is a very active breed the Bullmastiff typically requires less exercise than average for a dog of their size, so 60 to 90 minutes of vigorous activity a day is usually sufficient. Along with daily walks, these dogs are adept at drafting and carting activities, agility training, tracking, and obedience training. During your dog’s formative years it is important to keep exercise sessions somewhat shorter by breaking them up throughout the day and to ensure that your dog does not roughhouse or jump from a significant height as this can damage the still forming bones and joints. This crossbreed prefers the room that a house provides, but if given extra exercise 2 to 3 hours a day, they may be able to adapt to apartment life as they don’t tend to bark much. 

Bull Mastweiler Owner Experiences

Joe LaDouche
2 Years
4 People
House & Yard
Rescued from an abandoned farm at about 8weeks. Took two seconds to fall in love with him. Two days to house train him. Shows signs of separation anxiety so for the most part he goes everywhere with me. He's been my best friend since the day he came home
1 month ago
Book me a walkiee?