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© by Fred Lanting (mid-97), edited by Bobbie Impellizzeri 14 March 99 |
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In the release, the opening
statement that:
"Breeders working with
the OFA have reduced HD by 29% and increased the rate of 'excellent' by
56%" is certainly good news, but let's look at it more closely.
First, the OFA acknowledges that "breeders we work with are a subset of the general population" and states, "People who consistently use OFA's services have shown progress in the hip status of their dogs." Yes, that means that people who are buying puppies from those breeders have a much better *chance* of getting a normal dog. But remember, these are averages, and the buyer must still beware. Always try to get as much information on the hip and elbow status of parents, grandparents, and siblings, if any, before you buy.
Second, remember that figures reported are definitely skewed. As more vets get to see the good breeders' dogs, and as they X-ray more dogs, they get a little better at reading the films and giving you a more accurate diagnosis or prediction. Some years ago, OFA surveyed the readings of private practitioners and found that more than half read the radiographs WRONG... and in both "directions"; i.e., some read good hips as being bad, and some read dysplastic hips as being normal. Some dogs have even been put down as a result of erroneous readings. Don't let vets euthanize a dog unless YOU can easily see the dysplasia on the film and the dog is in obvious, continued or chronic intermittent pain.
The skewing of statistics results (in part) from more films NOT being sent to OFA because the vet has become more adept at spotting HD, thus saving you the OFA reading fee. Usually, the worst hips don't get reported to and recorded by OFA. Of the films that DO go in, these are the better hips and naturally the picture will look rosier than before.
The increase in percent of submitted hips graded "excellent" is indeed good news. OFA executive director Dr. Greg Keller acknowledges that, "the decreasing percentage of dysplastic hips can be due to prior screening" (the skew I mentioned), but he also maintains that the "percent excellent" is a good barometer of progress (WITHIN THAT COMMUNITY REGULARLY USING OFA, REMEMBER).
Say that your vet sends ONLY films of hips within a normal, non-dysplastic range, because people no longer feel like paying OFA for confirmation of obvious dysplasia. If that "normal range" has more films falling in the "excellent" category than used to be the case, that means that those breeders are conscientiously selecting for good joints, because the entire spectrum of hip quality has been shifted toward the normal end of the random range. Thus, more hips are going to fall into the far (best) end of the bell curve and fewer into the really bad end. It is known that breeding selection for normal hips results not only in fewer cases of HD, but also in lower average severity. And this is why we have cause to rejoice: the higher relative numbers for "excellents" is indeed a sign of progress.
Is the rate of progress satisfactory? For some, who use only the best OFA grades (Good and Excellent) - probably - but then they have always been the "A and B students" anyway. The average doesn't really apply to those folks any more than average intelligence has much meaning for Mensa members, or average body fat has for the marathon runner. Those leaders in their fields are unaffected by what the hoi polloi do.
For breed clubs and the sport in general, perhaps the rate of progress is much too slow. If you imagine all the multitudes of GSDs out there, including "junk-yard dogs" and those who would never enter your breeding scene, they would act as a severe brake on progress. Even if you deduct them from the equation, you still have to consider the so-called "responsible" breeders in the US, who go ahead and take your stud fee regardless of the bitch's or the stud dog's hips or producing record or relatives' hips.
There are numerous "big-name breeders" who have resisted implementing requirements that ROM and Selects (GSDCA) have OFA or equivalent clearance; they are too preoccupied with the almighty buck and in preserving their image as a top breeder (i.e., preserving their egos at the expense of the quality of the breed). Then there is the German, or import dog, with the "a" stamp given at an age when only perhaps 70-75% of dysplasia is detectable with the standard ventro-dorsal AVMA view. Compounding that problem is the fact that the "a" stamp (of approval) is awarded to these young dogs regardless of whether they have normal, near-normal, or "still permissible" hips. That latter category includes many mildly or moderately dysplastic dogs. Progress is necessarily slower when not limited to just the "excellent and good" or "a" normal categories. Even around half of the ‘near-normal' "a" stamp dogs will fail to pass OFA's standards for certification.
And then there's the matter of more demanding radiographic methods than the AVMA "standard" view used by OFA. PennHIP technique uses a more normal position of the dog and a comparison of films when hips are squeezed together versus the femoral heads levered outward from the socket, plus a numerical value of the difference similar to the BVA number-value approach. PennHIP claims this is a much more revealing method than OFA's, especially with younger dogs. Presumably, then, using more stringent methods would increase the rate of progress much faster than either the SV or the OFA have been able to do.
The OFA has branched out into such fields as von Willebrand's Disease, copper toxicosis, enzyme deficiency, patella disorders, CMO (a disorder affecting mostly the skull of a few breeds), thyroid problems, and congenital heart defects. One might well ask, if they are into these areas, why not also provide statistics and registry service for dogs examined under PennHIP protocols? After all, this IS "orthopedic" and fits the original mission of the OFA.
While the rate or incidence of 'excellent' hips has more than doubled in 19 breeds since 1980, the German Shepherd (and its breeders who participate in screening and submitting films) show a 32% increase in % 'excellent.' The list of breeds and improvement was limited to those with more than 400 dogs evaluated before and up to 1980, so they could be compared to those evaluated in 1993-94. With such figures in mind, If you liberally salt the news releases that OFA has given us most recently, you can extract and set aside that portion which does not adequately address either the skew or the method, and concentrate on the truly meaningful statistic of increased OFA 'excellent' ratios.
OFA also released figures on its elbow registry. As you know, there are at least three types of elbow "dysplasia", with one or two being very common to certain breeds. The GSD has its highest incidence in either FCP (Fragmented Coronoid Process), or the one that most people recognize more often and earlier, UAP (Ununited Anconeal Process). Six breeds have submitted at least 100 dogs' radiographs, and it appears that the GSD improved 15% from dogs born before 1990 to those born in 1993-94. The significance of the preliminary data might not be great, but as more time goes by, a clearer picture should emerge.
Meanwhile, you can choose
to completely ignore statistics, but if you ignore the risk and reality
of the problems, you and your dogs will suffer. Have your dog's hips
and elbows evaluated, publish the results, and breed only the best.