After continually speaking to other large breed dog owners and veterinarians they all had different theories one in particular that most breeders and veterinarians agreed with was that HD is a combination of environment and hereditary factors. The dysplasia term means "improper growth ".

Why hip x-raying and scoring is still a valued technique to being able to determine if a dog has good or bad hips or even determine weather a dog has HD, we need to see the valued score as only being partial of the environment and hereditary factor considering that most breeding dogs are scored at the age of two years.

So which part and what percentage of the score is hereditary?   NO ONE can answer that question as HD still has so many other contributing factors that even today are still being explored and examined.

By applying the below methods with our Bullmastiffs we have raised over the past six years our hip score results have halved.

So what does the environmental contributing factor mean? Growth rate, diet and exercise. 

Exercise
This is generally a topic of discussion between many Bullmastiff puppy owners as to how many minutes or miles or kilometres, when the question that should really be asked is how strenuous should exercise be.  As a breeder I tell all of our puppy owners don't exercise instead allow the puppy to exercise themselves as they know when they have had enough. The addition of toys and bones will stimulate play , but if you have to walk your puppy A GENTLE STROLL on level ground of ten minutes a day is more than sufficient for a growing puppy (growing puppy includes those that are up to the age of twelve months despite their size) avoid hard surfaces and sand as a puppy needs to work harder on these surfaces.   Avoid puppies running up and down stairs and jumping up and standing on their hind legs. Overall allow puppy plenty of rest and never force them into strenuous activities. Swimming is also of great benefit as this is a low impact exercise.

Growth Rate and Diet
Overfeeding and over supplementation during the most active growth period has also been suggested as a significant cause of HD. It is because of the high calorie (protein) intake over this growth period that almost has a steroid effect on growing puppies thus causing a large breed puppy to grow to rapidly and causing bone and joint disorders.   It is preferred by most breeders, veterinarians and OURSELVES that an adult dog kibble be feed with a protein level no higher than 25% and no further supplementation of other vitamins and minerals.  A controlled diet is necessary to avoid your puppy Bullmastiff in becoming overweight.      How much to feed really isn't the concern but weather or not your Bullmastiff looks either to thin or obese. You should be able to feel the ribs without digging, a Bullmastiff should also have what is known as a tuck at the waistline. Obese Bullmastiffs also carry allot of other health concerns.

Hereditary
Also being a contributing factor we still as breeders need to hip x-ray and score our breeding dogs.  I would certainly NOT endorse breeding from a dog that has a high score as I have suggested above we still don't know what percentage is environmental or hereditary.    Bullmastiffs still inherit from their parents shape, strength and growth potential of the hip joint. Although these are inherit to some degree we do have to conclude that only breeding from low hip scored dogs will simply NOT eradicate this disease known as hip dysplasia but controlling the environment and hereditary factors we can certainly lower the severity and causes of Hip Dysplasia.