The Hip Dysplasia Prevention Conundrum: PennHIP vs. OFA Round Number?
For the past few years I've been worrying at the edges of this issue, wondering what, perhaps, might be done about the fact that hip dysplasia is a bad disease that doesn't seem to go away. Like tonguing a bad tooth into dubious submission, the subject's only festered all the while. This week, however, I decided to do something about it.
Hip dysplasia happens when the bones are badly designed during the pup's fetal development. They are poorly fit together at one or both of the hip joints, so that painful rubbing leads to the kind of crippling arthritis that is evident in rickety old dogs whose legs splay out painfully just before they're pronounced dead by a condition effectively known as, "She can't get up, doc."
Sure, we can "replace" hips with an elaborate set of implants, or employ earlier tactics of resecting bits of bone to reduce the painful rubbing, but these are all solutions that are undertaken in less than two percent of my hip dysplasia patients. The cost and stress of surgery doesn't appeal to most pet owners, it would seem. It becomes even less appealing when the truth is that there are no guarantees with any kind of orthopedic surgery, much less a hip procedure.
So what's a hip dysplasia sufferer's keeper to do?
Maybe not much, beyond surgery (which I do strongly recommend for specific candidates) and all the palliative approaches that really can make a huge difference (here's a post on this). That, again, is the sad reality of this disease.
Luckily, there is one way to deal with it: prevention.
What a concept! Since this is an inherited disease, it is an eminently preventable disease. All we have to do is identify the dogs with bad hips and cut them out of the genetic loop, as it were.
Easier said than done. Testing is required. And since it's no simple blood test — X-rays, sedation and the like are required — it can get pricey. Even pricier if you go for an elite service called PennHIP. Here's an excerpt from a past post on the subject:
For those of you whose breeds are predisposed to hip dysplasia, you might know that the OFA (Orthopedic Foundation for Animals) and PennHIP models represent rival technologies for assessing dog hips. You should also know that I consider the PennHIP model superior.
(To read the rest of the post, click here.)
In case you're wondering, I offer a wide variety of reasons why this should be, including a list of what I think are well-balanced pros and cons. And yet, OFA remains a far more popular method than PennHIP for assessing hip dysplasia. This, in spite of several scholarly papers pointing in PennHIP's direction.
Sure, they were mostly undertaken by PennHIP's people, a fact not lost on any skeptical reader (and most of us are). And yet, can you blame them for wanting to get the word out that they're trying to do science, getting better than decent results (repeatedly) and still feeling no joy from the wider crowd of practicing veterinarians?
The most recent publication in support of the PennHIP method was undertaken by the same team at the University of Pennsylvania that pioneered the method. It again shows that OFA is an inexact approach for identifying hip dysplasia; it misses this condition in a great many cases, thereby perpetuating the disease's high prevalence.
A couple of weeks ago I happened to receive personal confirmation of this tragic truth. A middle-aged Lab whose hips had been graded "very good" (one of the highest subjective grades applied by OFA) came up lame. X-rays confirmed it: arthritis symptoms and a poor hip fit typical of bilateral hip dysplasia. No doubt about it. The "very good" grade she received at two years of age was not predictive of her disease at age seven.
With four to six years left to live and two litters of pups pups behind her, where did that leave this dog and the yet-to-be-bred population of Labs out there?
This is exactly what this study in the most recent JAVMA (Journal of the American Veterinary Medical Association) addressed: If there's a better way to prevent this kind of tragedy by identifying the disease earlier and more precisely, why are we not doing it?
Dr. Patty Khuly
*Hip diagram courtesy of BASC