THE PENNHIP PROJECT
PennHIP Versus OFA
By Judy Huston
It is often difficult to know where to focus our energy to make the most improvement and do the most good for our breed. The White Shepherd is a herding and working breed and most people will agree that one of the major hereditary problems is Hip Dysplasia. Since we now have PennHIP which is an alternate method of assessing hips, this article is an attempt to clarify the differences and to suggest that PennHIP could help breeders produce dogs with tighter hips. I look at PennHIP as a possible tool breeders could utilize to reduce affected dogs and carriers of HD in our breed.
It seems, to paraphrase Fred Lanting who wrote Canine Hip Dysplasia and Other Orthopedic Disorders that using OFA and OVC instead of PennHIP is like using an axe to cut down a tree when you have a chain saw sitting on the trunk of your car. OFA and similar hip-extended methods use a grading system of Excellent, Good, or Fair, or a Pass/Fail. Some would argue that these methods have not reduced the incidence of Hip Dysplasia as much as expected. There are some breeders happy with their results, but there are many from our breed and others who have become disillusioned. We have heard our own breeders lament the fact that they bred two excellent dogs and still produced HD. It is interesting that in the ten necropsies we have on file as part of the White Shepherd Genetics Project research, two dogs with OFA clearances had HD. In another case in our Open Registry, a dog had an OFA score of Good at the age of two, but was diagnosed with mild hip dysplasia at the age of five. Their owners thought they were “clean” but they were not.
The Distraction Index (D.I.) as measured on one of the views taken by PennHIP is the predictor of a sign of risk for eventual HD/DJD (HD and DJD both signify Hip Dysplasia). A D.I. of 0.28 is the “magic threshold” for the GSD. This is the D.I. under which it is virtually certain there is no Hip Dysplasia/DJD. Over 0.70, there is a very high risk of HD/DJD. The higher the number the higher the risk. The lower the number the tighter the hips. The closer the numbers are to 0.70, the higher the risk of Hip Dysplasia.
We’ve been conditioned to believe when we have a dog that passes OFA or OVC that they are free of HD—or clean, but according to the PennHIP method of evaluating hips, this is not always the case. Some of the dogs that have passed with the hip-extended method really have a false negative. In other words, their hips look good with legs extended, but when the measurement is taken to see how tight the socket is in the hip (the Distraction Index), the dog may have a higher than average risk of developing Hip Dysplasia or may already have HD. It will be very interesting to note the variability in the Distraction Index in a group of dogs with a passing OFA of Fair, Good, or Excellent to the distraction index.
PennHIP states that the way to improve the hips in any breed is to only use dogs in the top 30%
(70th, 80th, or 90th percentile). Don’t let the D.I. index numbers or the percentiles confuse you. Just remember the lower the D.I. number, the lower the risk, and the higher the number the higher the risk. If a dog was evaluated as having HD/DJD on the PennHIP report, that information is given along with the D.I. otherwise the dogs are free of H.D. The percentiles indicate where a dog stands in relation to the rest of the breed. In the 90th percentile means these dogs have tighter hips than 90% of the breed.
When a report is received from PennHIP, it shows the number of dogs in the breed at the point in time the test was submitted. It shows the median number which for our breed is 0.40 (as many dogs under this number as above it), and it shows the percentile which can change over time.
PennHIP is an advanced tool and the conclusions listed in Lanting’s book state:
ü Tighter is better (agreed on by PennHIP, OFA, and other groups)
ü Position and technique can discover covert laxity (PennHIP) and it is the covert laxity that you can’t see on the OFA/OVC views
ü Creating open registries and using Breed Value Data will result in faster progress, and
ü PennHIP is the best diagnostic-predictive tool currently available.
At the PennHIP/OFA seminar at my home on August 29, eleven breeder/owners had the privilege of seeing a PowerPoint presentation by a PennHIP certified vet, Dr. William Schultz of Okemos, Michigan. He pointed out that with OFA, the hip-extended position is not a normal resting position and that extending the legs causes tightening of the joint capsule (which could make the joint look better than it really is) and there are repeatability concerns. While with PennHIP, the doctors are certified and continually evaluated. The dogs are under full anesthesia and there are three views required: the OFA view, the compressed view, and the distracted view—and all MUST be sent in, unlike with OFA--if the hips don’t look like they will pass, they often aren’t sent in. In Doctor Schultz’ view, PennHIP is the smart way to go to improve the hips of any breed.
A final quote from Lanting’s book (and which was also Dr. George Padgett’s philosophy) states that: “Hip quality, as important as it is, is not the whole dog. A stud with 0.35 may benefit the breed more than one with a 0.28 DI because of a combination of other phenotype features. Better breeders keep the whole dog in mind, while at the same time they know that the increasing DI means increasing risk of HD.”
As a result of the almost $20,000 received from the Cesar Milan seminar, the WSGP is in a position to do some research in the PennHIP area. As of today (February 26, 2007), I have 93 dogs listed on my PennHIP chart. We already had a family of dogs with PennHIP and we offered to pay $200 towards the procedure which can range from just under $200 to close to $600 depending on the part of the country you live in. Quite a few people elected to particpate, and soon, the results of more dogs in this family will be submitted and we’ll have our first look at what a White Shepherd PennHIP database would look like.
We may approach PennHIP to list this group of dogs as White Shepherds (with the owner’s consent of course) so that they will keep track of our ranges, but even if they don’t, as a result of this project we’ll have a healthy group of dogs to work with to determine for ourselves that PennHIP is the most powerful tool out there to improve the hips in our breed.
One way to start incorporating PennHIP into your breeding program is to add the price of the PennHIP into the sale price of the puppy. Make doing PennHIP at 4-6 months a requirement of your contract and tell your puppy buyer you will pay for it. Sell pups on a no breeding contract until you know their score. Over a relatively short time, we should be producing dogs with tighter hips and be confident that this is one disorder that we have under control. After all, our dogs are from the herding group and working is what they are bred to do. They need to be sound to do the jobs they were made for.
We also have one dog in the project that had the procedure as a young dog and will do it again as one example of repeatability. We have two other eight year old dogs that will have it done for the first time. The next step will be to encourage dual testing so that we have both PennHIP and OFA on as many dogs as possible.
If you have questions about this, please contact me by e-mail. hustonjudy@gmail.com. Clearly, not everyone is sold on PennHIP but, hopefully, this work will educate us all about his method.