This powerhouse of a dog weighs between 100 and 130 pounds and has a mind of his own, with the muscle to back his intentions. He’s devoted to his human family, particularly children, so a well-bred, well-socialized Bullmastiff is an excellent family dog. Just be sure to set boundaries with him from a young age; he needs lots of firm, consistent training and exposure to all kinds of people and situations to develop the common sense and instincts to temper his strength and encourage his kindness.

Traits, Personality and Behavior

Despite his size, the Bullmastiff can live in an apartment if you don't mind constantly bumping into or stepping over him. He doesn't need much exercise, nor is he much of a barker. His grooming needs are modest, too: Brush him a couple of times a week to keep shedding to a minimum, and make sure his ears are clean and his nails are trimmed.

What he does need is to be a part of the family. This is a dog who forms very deep bonds to the humans with whom he lives, and isolating him in the yard or the garage, or expecting him to spend most of his time alone, is guaranteed to make him a very unhappy dog -- and a very badly behaved, destructive and possibly dangerous one based on his size.

Make him a family member, and he'll be a strong, mostly silent guardian of your home and children, and an intensely loyal companion. His training and socialization needs to be taken seriously, starting when he is a puppy before bad habits have a chance to take hold. In particular, you need to teach your Bullmastiff not to pull on the leash or jump on people, or he'll be a hazard to anyone he's around when he's full-grown. This dog can knock an NFL linebacker off his feet.

Bullmastiffs usually love children, but the reality of a dog this big is that he can unwittingly hurt or scare a child. Be cautious and always supervise dogs and kids when they're together. If you have toddlers, consider waiting until they're older to bring a Bullmastiff into your family.

However, the Bullmastiff does not love other dogs, particularly if he's a male and the other dog is, too. It's extremely difficult to house a male Bullmastiff and another male dog of any breed together. Even dogs that live in peace for years can one day become implacable enemies. They also can have a high prey drive, and many Bullmastiffs cannot live with cats for that reason.

Health Issues Common to Bullmastiffs

As might be predicted, given their large size, Bullmastiffs suffer from a number of joint and structural problems. It's important that young, growing Bullmastiffs be kept lean and not allowed to exercise too strenuously or eat too much, as this will lead to injuries and problems that can be crippling down the road. In fact, all Bullmastiffs need to be kept lean, as obesity increases the chances they'll develop structural problems, and makes them more painful when they do occur.

One such structural problem is the genetic hip deformity known as hip dysplasia. The head of the thigh bone doesn't fit properly into the hip socket, and over time the bone begins to wear away. The constant inflammation leads to arthritis. It's treated with surgery, usually total hip replacement, at the cost of thousands of dollars per hip. Untreated, the dog will suffer pain and lameness. Elbow dysplasia is a similar condition affecting the elbow.

It's impossible to know if a dog has hip or elbow dysplasia simply from examining him or watching him move. Nor can hip and elbow dysplasia be ruled out entirely just because the parents were free of the condition, although it reduces the risk. And a puppy's hips and elbows can't be evaluated; only at the age of two you can know if a dog is or isn't affected.

This condition can only be diagnosed by X-rays that then need to be evaluated by an orthopedic specialist. Each Bullmastiff owner should have his dog's hips and elbows X-rayed at two years of age, regardless of whether or not he shows symptoms of lameness or stiffness.

The Bullmastiff is also at risk for a number of heart problems. These include cardiomyopathy, which causes an enlarged heart, and subaortic stenosis, a narrowing of the aortic valve caused by a fibrous ring of tissue.

An annual heart exam is critical in catching these conditions early. The sad reality, however, is that a dog who tests fine one day can develop heart disease the next, and the puppy of two parents without heart disease can still develop it.

Bullmastiffs are also more likely than many breeds to bloat, a condition in which the stomach twists on itself, cutting off blood flow. Bloat strikes very suddenly, and a dog who was fine one minute can be dead a few hours later. Watch for symptoms like restlessness and pacing, drooling, pale gums and lip licking, trying to throw up but without bringing anything up, and signs of pain. Bloat requires immediate veterinary surgery, and most dogs that have bloated once will bloat again. That means it's wise to opt for the procedure known as "stomach tacking," which will keep the stomach from twisting in the future. This procedure can also be done as a preventive measure.

Cystinuria is a genetic kidney defect that leads to the formation of bladder stones that are very difficult to manage with diet or medication and often require surgery both to remove the stones from the bladder and to repair urinary blockages. There may be no advance signs that the dog is forming cystine stones and many veterinarians are unfamiliar with cystinuria and may mistake them for more common stones such as struvites. Urinary blockage is a life-threatening veterinary emergency.

Unfortunately, the current screening test for cystinuria is of limited use, as it frequently gives a false negative. It does not give false positives unless the dog is on a particular type of antibiotic at the time the urine sample is taken, however, so a dog that tests positive does, in fact, have the condition, even if he tested negative in the past or tests negative in the future. There is no genetic screening test, so it's impossible to determine if a dog is a carrier or not.

Bullmastiffs are also at increased risk of a number of cancers, including some forms of lymphoma and hemangiosarcoma, as well as osteosarcoma (bone cancer).

To protect yourself from the expensive vet bills associated with these conditions, you'll want to purchase pet insurance for your Bullmastiff before they show symptoms or are diagnosed.

Condition Risk Profile Cost to Diagnose and Treat
Gastric Dilatation Volvulus (Bloat) High $1,500-$7,500
Cardiomyopathy Medium $500-$1,500
Hip Dysplasia High $1,500-$6,000
Elbow Dysplasia High $1,500-4,000
Aortic Stenosis Medium $500-$1,500

7 Tips to Bring Home a Healthy Bullmastiff Puppy

Don't ever, ever, ever buy a puppy from a pet store or Internet site that offers many breeds and popular mixes, or that ships with no questions asked. If you buy a puppy from these sources, you'll be more likely to get an unhealthy, unsocialized and difficult to house-train puppy and will be supporting the cruelty of high-volume puppy mills.

Start your search for a good breeder with the American Bullmastiff Association which maintains a list of registered breeders.

Ask your breeder to show written documentation from the Orthopedic Foundation for Animals (OFA) and the Canine Eye Registration Foundation (CERF) clearing your puppy's parents of hip and elbow dysplasia, heart and thyroid disease, and eye problems, including a DNA test that the parents are clear of progressive retinal atrophy, which can cause blindness. PennHIP certification of hips is also acceptable. Screening for several different kidney diseases that can affect the breed, including a rare condition known as cystinuria, is also recommended.

Consider your dog's temperament. While most Bullmastiffs do have sound temperaments, because of their size a breeder who has American Temperament Test Society (TT) certification on her dogs is to be preferred over one who does not. A good breeder will welcome you to meet her dogs as well.

Don't fall for the lies of unethical breeders. These sources will have a thousand excuses -- such as that they don't need to do those tests because they've never had problems in their lines, or because their dogs have been "vet checked" -- as to why they haven't done the health and temperament testing that good breeders do, but that's all they are: excuses. The minute you hear something like that, walk away.

Consider an adult dog from a shelter or a rescue group. Because many young Bullmastiffs are a handful, and many healthy defects hide until maturity, you can avoid both problems by adopting an adult Bullmastiff (or mix) from a rescue group or shelter.

Puppy or adult, take your Bullmastiff to your veterinarian soon after adoption. Your veterinarian will be able to spot visible problems, and will work with you to set up a preventive regimen that will help you avoid many health issues. Ask specifically about what to do it if you suspect your dog is bloating, and how best to monitor your dog for other potential health risks.

Make sure you have a good contract with the seller, shelter or rescue group that spells out responsibilities on both sides. In states with "puppy lemon laws," be sure you and the person you get the dog from both understand your rights and recourses.

Pet Insurance for Bullmastiffs

Pet insurance for Bullmastiffs costs more than for mixed breed dogs. This is because Bullmastiffs are much more likely than mixed breed dogs to make claims for hereditary conditions that are expensive to treat.

Embrace dog insurance plans offer full coverage for all breed-specific conditions (excluding those that are pre-existing) to which Bullmastiffs are susceptible. The best time to get pet insurance for your Bullmastiff is when he's a healthy puppy. You can't predict what will happen in the future, and pet insurance is the one thing you can't get when you need it the most.