HIP X-RAY ACCURACY

Utility & Reliability: PennHIP vs. SV and OFA Hip-Extended Views

Fred Lanting, November 2013

First, some facts:

• The “standard” view (positioning of dog for X-ray pictures of hips) is not the best… it is not the most accurate way to determine the real quality of hips. OFA, SV, and other registries have the dog stretched out on its back with legs straight out on the table, for the X-ray picture. While this is good for showing joint deterioration at the time, it is not accurate in showing true looseness, and it is not good for predicting what the hips will look like in a few years, when perhaps the dog has already produced puppies that inherit its hip quality.

• Accuracy in diagnosis and prediction, using that old ventro-dorsal position (lying flat on its back) increases with age of the dog being “X-rayed” (radiographed). At one year of age, which is when the SV starts “certifying” dogs, accuracy in predicting mature hip quality is rather poor—only the worst are identified when young, so progress in reducing incidence of dysplasia is still relatively poor.

• The SV has recently required a second hip radiograph after a dog has produced a certain number of litters, but popular dogs will still have put far too many dogs on the ground by then. That means many buyers will be stuck with pups that have less than ideal hips or chances of being valuable to the bred in that regard.

• The greater the number of truly “normal” ancestors in the near pedigree, the greater the odds that your dog will have good hips, meaning that it will have a better chance of avoiding both orthopedic problems itself, and of passing problems along to descendants.

• The only technique that gives an accurate, early, and relatively unchanging look at hip quality is the PennHIP technique and evaluation service. It is an abbreviation for “(U. of) Pennsylvania Hip Improvement Program” developed at that university, and is available in a great number of countries. The German hierarchy (at least in the GSD world ruled by the SV) has typically, stubbornly resisted the better science of PennHIP and has thus condemned its members and followers to a world of limited improvement.

I have written longer explanations of the dysplasia problems and these can be found on Internet sites, as well as a comprehensive look in my large book on canine orthopedic problems (you can do an Internet search for my name and address if you want to order one). The purpose of this current paper is to give a shorter introduction and to encourage you readers, buyers, and breeders to use the better tools available. This will give you much better chances of avoiding hip dysplasia in the pups you buy or sell.

The PennHIP method of determining present and future hip quality has many advantages: Repeatability is one, which means that the results when radiographed at any later age will be extremely close to those obtained at a young age such as 5 months, before much expense is put into a dog in advertising, selling, and training. It is heartbreaking to put so much time into training only to learn at a year or older that the dog is not of breeding quality in its hips. So economy is advantage number two. Perhaps the third advantage is the population-genetics one, meaning that by enough breeders using this technique, the average quality of all dogs will be improved.

The following drawing shows the positions of the dog and the patented PennHIP distraction tool. The only vets authorized to take these pictures and submit them to Penn for certification, evaluation, and entry into the data bank are those who have gone through the one-day training program and have successfully submitted enough approved radiographs from their own practice (so their technique can be evaluated before they are added to the list of recommended veterinarians).

The primary predictive indication of DJD (degenerative joint disease, which is another term for HD) and the main definition, at least in young dogs, is joint laxity. This is best revealed by the PennHIP method for two reasons: better accuracy, and detection at younger ages. While we cannot see genes, we can get a vastly better idea of their relative “quality” or power to produce certain hip qualities, by using the PennHIP method. Certified vets (those who’ve successfully gone through the seminar and testing procedure) can be found by visiting the PennHIP website and looking in your country, state, or zip code for those near you.

We cannot state too often that PH accuracy, efficacy, and dependability in early identification of the prime aspect of HD (joint laxity) is your best assurance. Even evaluated at 4 months of age, PH is more than 90% as accurate as the old-standard AVMA/OFA/SV diagnosis at 24 months, and those 5 or 6 months old have repeatability statistics approaching 100%. Indeed, one day the PennHIP method will be the “standard.”

The biggest problem with the old-fashioned ventro-dorsal position still used by SV, OFA, and others, is that at the ages most dogs are sold to new homes, about half of the hip radiograph evaluations will be erroneous… we call these “false negatives” and as such, they represent great economic risks to the buyer. The DI (distraction index) numbers reported by PennHIP evaluations help you avoid the loss of time and money in the purchase and upbringing of your pups, and any dissatisfaction by your customers. OFA’s published reliability figures have been erroneously high; the percentages of false negatives as well as false positives were not valid, and one can extrapolate those inaccurate results to apply to SV, FCI, and any other old-style v-d-position registries. Then, too, most of their radiographs of bad hips are never sent in, which avoidance technique is not allowed by PennHIP.

If breed clubs and registries would adopt the PH compression-distraction method as a far better revealer of probable hip genotype in the individual and its progeny, it will represent a quantum leap in genetic hip-disease control. The very best and fastest improvement would be had by using this stress radiography for early and accurate diagnosis, plus Zuchtwert or Breed Value assessment with its use of progeny information and an open database on relatives. Simply put, PennHIP and its DI rating represent a more rigorous, demanding, safety-satisfying look at laxity and risk. It allows a clearer picture of the genotype by offering, at younger ages, identification of the most likely carriers of bad or good genes, a more quantitative evaluation (numerical index), and faster progress in reducing the incidence of HD.

TheDogPlace.org EST 1998 ©  Feb 2013 164 https://www.thedogplace.org/Genetics/X-ray-Accuracy_Lanting-1312.asp

Fred Lanting is an all-breed judge with experience in over 30 countries. He is a well-known GSD authority, handled Akitas in the 1960s and `70s, and was named an official JKC judge, a rare honor. He has lectured around the world on breeding, judging, canine movement, and CHD (canine hip dysplasia).   Be sure to peruse these Dog Books by Fred Lanting

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