Hip Dysplasia

Over the last three years we have developed a conviction and taken a stand on the issue of x-raying the hips of American Bulldogs.  It has been an interesting journey with plenty of heartbreaks, some triumphs, and seemingly a new surprise around every corner.

The hip status of this breed has fortunately been in the forefront of late.  In the flurry of words surrounding this subject, not a few jabs have been made against breeders who have taken a stand on this issue, usually to the effect of  ``…  who breeds only for hips…".  Having rubbed shoulders with most of those against whom this charge has been leveled, I don't know of anyone who fits this description.  Rather those of us who have chosen to use hip evaluations as one of the criteria for our breeding stock use a number of other selection requirements, which vary from breeder to breeder.  The exceptionally tight-hipped dogs in such current demand as studs have many more outstanding attributes including bloodline, structure, and working aptitude as demonstrated through bitework, hog-catching, or flirtpole, and springpole play.  The hip status should be understood as just one of a number of essential components of a sound working animal.  With this in mind, we would like to candidly share the results of our own x-raying to date and explain some conclusions and …Okay.. opinions we are coming to.

The first Bulldog we x-rayed was our Hines-bred bitch, Molèque who we did an OFA evaluation on in September 1994.  The evaluation came back OFA excellent, a pleasing result by any standard. This initial positive experience became the encouragement in what we believe is a very elusive pursuit  the totally sound American Bulldog.  Hips, which we are addressing here are just one of the many components of the ideal bulldog.

METHODS

First I would like to explain the basis of our research.  The dogs that were selected for x-raying are first dogs that we have purchased or were considering purchasing for broodstock, and secondly dogs bred by us that we had retained as potential broodstock.  These dogs include almost all known bloodlines and a wide variety of sizes, with no size discrimination on our part.  None of those dogs were x-rayed specifically because we suspected hip dysplasia any more than any others, and for the purpose of our research, all dogs x-rayed were submitted either to the OFA or PennHip for formal evaluation.  An additional source of information is from the dogs we have sold and were x-rayed by the current owners who kindly (and sometimes for the purpose of a replacement) shared the results with us.  All dogs raised and x-rayed by us were fed only TechniCal dog food (Adult: 26% protein, 18%fat, Puppy:  28% protein, 18%fat), and were raised on a variety of surfaces including brick, concrete, grass, pea gravel, and dirt (younger puppies up to about 5 months normally on the harder surfaces, older puppies and adults on the natural surfaces).  In our early years, up until around 1995, our dogs and puppies were kept in a natural to a little over-weight condition.  The last several years we have tried to keep all our dogs, especially puppies, at a leaner weight to alleviate any possible effect on the hips from being overweight.  All dogs were raised with a moderate to (I'm ashamed to admit) low level of exercise.  Any dogs that were purchased as adults, or sold as younger puppies were of course raised in different conditions.

I have organized the information gathered from these dogs into two tables that I have labeled Figure1, which we will discuss in this article, and Figure 2 which I will publish and discuss at a later date.  Figure 1 is a list organized by date of x-ray of all dogs that we have been involved in (i.e. paid for) x-raying and/or submitting the x-rays to the OFA (18) or PennHip (38), a total of 42 dogs at this time.  Figure 2 is a complete (to our knowledge) list of x-rays of dogs we have bred, organized by litter.  For the purpose of space we have shortened the names where necessary and have only included what we consider to be the most pertinent information.  The OFA/preliminary column contains the OFA evaluations: the capitalized entries refer to an official OFA certification (done only on dogs over the age of two years old); those entered in small letters refer to OFA preliminary evaluations on younger dogs.

An additional topic I should address in this section is the use of the different hip evaluation methods.  The OFA has long been the established hip registry of choice, and was the way we initially evaluated our dogs.  The dog is normally (but not necessarily) sedated and placed on the x-ray table on his back.  One technician stands at the dog's head and holds the front legs and chest in position, while another pulls the hind legs down, parallel to each other and extending straight back in line with the dog's back.  The Orthopedic Foundation for Animals, then has three veterinary orthopedic specialists evaluate the hip joints in terms of placement of the femoral head within the socket, the overall conformation of the joint, and whether or not there are any signs of arthritis or other changes in the joint that are considered to be the definitive sign of hip dysplasia.  Radiographs done on dogs between the ages of 3 and 24 months are given a preliminary evaluation by only one specialist.

When our local veterinarian told us that he was being certified in the PennHip procedure, we decided to experimentally evaluate some of our dogs according to their standards.  The PennHip was developed on the thesis that it is not the conformation, or even the placement of the head of the femur within the socket that determines a dogs predisposition to developing dysplasia, but rather the animal of laxity within the joint as can be measured with the PennHip positions under sedation.  This determination of joint laxity is performed by comparing a compressed and a distracted view of the hip joint, measuring the distance the bone moves within the socket, and dividing this number by the diameter of the head of the femur to give a decimal ``Distraction Index", hereafter referred to as D.I. (Example: If a dog has a femur whose head measures 1 inch across, and that femur moves ½ inch in the socket, as measured by the PennHip x-ray methods, its D.I. would be 0.50.)  A third shot identical to the OFA shot is also taken in order to allow for a description of whether or not there are any arthritic or other changes within the joint. In summary, the OFA looks at the conformation, the placement, and for arthritic changes while the PennHip looks at the passive laxity, and also for the presence of any changes.

The appeal and argument for the PennHip is that the joint laxity is genetically determined and that it is remarkably constant throughout a dog's life, thus allowing the possibility of early diagnosis of hip problems before too much time and energy have been expended.  Of course while the PennHip organization touts this as fact, the OFA passes it off as questionable at best.  Because both organizations stand much to gain financially as well as ideologically, their arguments should be taken with a grain of salt.  The reality is to be determined by the layperson you and I.