A recent JAVMA article titled “Evaluation of the relationship between Orthopedic Foundation for Animals’ hip joint scores and PennHIP distraction index values in dogs” and a recent VRUS article titled “The Effect of a Technical Quality Assesment of Hip Extended Radiographs on Interobserver Agreement in the Diagnosis of Canine Hip Dysplasia” raise questions about the value of the legs extended “OFA projection” as a way to evaluate for the presence or absence of hip dysplasia in young patients. Is recommending OFA certification to our clients starting to border on the irresponsible?
In the JAVMA article, the authors concluded that young dogs with significant laxity were judged as OFA certified for breeding despite significant laxity and failed to identify osteoarthritis susceptibility in 80% of the dogs in the study that were judged phenotypically normal by OFA. Ouch!
In the VRUS article, a conclusion was made that interobserver agreement on dysplasia/nondisplasia and final scoring remains low even among experienced observers.
Although this post is not meant to summarize all of the research on the benefits of Penn Hip vs. OFA if you accept these research articles as valid, how can we conclude anything other than “this test does not do what it says it does and even if it did, we don’t even know how to interpret the darn thing?”
Is recommending OFA a responsible thing to do?
Considering these two studies, the question needs to be asked whether we, as veterinarians and radiologists, are being responsible when we offer our clients OFA radiographs or interpret these radiographs as an assessment of the presence or absence of hip dysplasia in young patients.
For the record, I consider myself a culprit in this debacle and I write this article as I debate whether or not I continue to interpret OFA projection radiographs in young patients and if I decide to do so, how I will word my radiology reports.
Routinely, I receive films from young patients as a hip screening for breeding purposes or in young military or police dogs where clients are attempting to decide if our local or federal government should make a decision to enter this dog into training. In these cases, I read the films as I feel that I am able to interpret them as well as the next guy. In my conclusions, I always mention PennHip as a more definitive alternative and I routinely contact the veterinarian to discuss the limitations of the study/interpretation.
Nonetheless, these cases always leave me feeling if my ethics have been compromised. Sitting in my dark room I ask myself:
- Is the job of the radiologist to maintain the standards of veterinary radiology at the expense of making a living? Should I reject these cases at the result of losing a client even though I can read the films as good as the next guy?
- What if this were my mothers dog and another radiologist issued this report – what would I say to my mom?
- Am I hiding being the fact that if I do not read these cases someone else will and because no veterinary authority has put the OFA projection to rest this is simply practicing according to the current standard of medicine.
- Why do veterinarians continue to recommend the OFA projection in young patients as an assessment of hip dysplasia? Is it because it is easy and lucrative and does not require a weekend certification course (as does PennHip). It is because we just do not know any better?
In a day and age when veterinarians are calling for evidence based medicine, perhaps we should start following the medicine we have evidence for and stop recommending OFA certification in young patients. Perhaps we should put the following disclaimer out to pet owners before we perform an OFA evaluation…
“Hey owner – I have this test we can do to look for hip dysplasia. It really only works well if your dog has severe disease. In most cases, where disease is so sever that this test will be meaningful, I can detect disease by simply feeling your dog's hips. In the vast majority of cases, however, the test does not really tell us much and we don’t even do a great job interpreting it anyway. I even have a radiologist that I can sent the test to who will tell us that unless things are really severe we don’t know much about whether or not your dog will develop hip dysplasia. If you are cool with that, I would be happy to take your money."
If your owner goes for the test after saying that….as PT Barnum once said1, “there is a sucker born every day.” Take their money and send me the films.
1. Actually it turns out he did not say this but did not deny saying it. It was actually his competitor but Barnum liked the free press: http://en.wikipedia.org/wiki/There%27s_a_sucker_born_every_minute