I had posted the following information regarding PennHIP on a different discussion forum. I am happy to share this information to help you decide if PennHIP is right for you and your dog. I apologize in advance for the length of this post.
I routinely have two hip evaluations performed on my dogs. One set of x-rays is submitted to Germany and the other to PennHIP. I am all for any procedure that takes the subjectivity out of evaluating x-rays (OFA) and replaces it with objective evaluations (PennHIP). I did some research before deciding on whether to use the PennHIP method my vet suggested and found the following.
The University of Pennsylvania Hip Improvement Program (PennHIP) was based on the work done by Drs. Gail K. Smith, Darryl Biery, and Thomas Gregor. Dr. Smith is a Veterinary Orthopedic Surgeon at the University of Pennsylvania, holds a PhD in Engineering, and was the lead in the development of this technique. I was not able to find much information regarding the background of the other two doctors.
The development of PennHIP involved several disciplines including biomechanics, clinical medicine, radiology, population genetics, and associated statistical analysis. The principle behind PennHIP, as a diagnostic tool, is that hip laxity is a measurable component that can be used to predict a dog's susceptibility to develop canine hip dysplasia (CHD) and degenerative joint disease (DJD) later in life. By applying the physical principles and biomechanical testing of the hip, PennHIP stress-radiographic methods can accurately measure hip joint laxity in dogs as young as 16 weeks. PennHIP requires that x-rays be submitted for evaluation regardless of whether the owner wants to or not. This differs from OFA in that the owner can decide whether to submit the x-rays for evaluation.
The primary difference in the PennHIP radiographic and diagnostic method and OFA is in the positioning of the dog during the x-ray procedure. Dr. Smith believes that a measurable amount of hip laxity is inherent in all dogs. The PennHIP method was developed to quantify the relative degree of femoral head displacement from the hip joint visible in a compression distraction view. This view requires the dog to be under deep sedation or general anesthesia and incorporates two views of the dog in the supine position and one view of the hips at a neutral position. Dr. Smith also believes the compression/distraction stress radiographic technique is 2.5 times more sensitive in quantifying hip joint laxity than the standard hip-extended method (OFA).
PennHIP's range of laxity is quantified on a Distraction Index (DI) scale from zero to 1. Hips approaching zero are extremely tight and hips approaching 1 are extremely lax and 100 percent out of the joint. The PennHIP method provides a "distraction index (DI)" score for each animal that is evaluated. Hips that show very low laxity (low DI score) are considered tight hips that are highly unlikely to have evidence of DJD.
As stated by PennHIP, their primary objective is to provide reliable, quantitative information to dog breeders that will allow them to make breeding decisions that can reduce the incidence of DJD and CHD in their lines. It is important to understand that PennHIP is not evaluating the animal in the familiar “pass/fail” manner. A given DI score does not exclude that animal from breeding consideration. What the DI offers the breeder is an understanding of where their individual animal ranks relative to other members of its breed (or the overall dog population if fewer than 20 bred members have been evaluated) with respect to hip joint laxity.
The guiding principle evolving from the PennHIP research suggests
“tighter hips are better hips and breeding tight hips to tight hips is the best approach rather than trying to breed looser hips to tight hips.” Is PennHIP 100% accurate, absolutely not. However, I personally believe it is the best method available today simply because none of the other evaluation methods has undergone testing through controlled scientific testing.
In my opinion there are a couple of reasons that prevent PennHIP from being utilized by breeders and owners more than it is right now. The first is the cost. The cost for PennHIP is significantly higher than OFA. The cost differential is because OFA requires a single x-ray of one position while PennHIP that requires three x-rays of the dog’s hips. I have found that the vet community has not established a standard fee when performing PennHIP x-rays.
I live in central Nebraska used to drive to Iowa State University to get my dogs PennHIP. Even though there are vets certified for PennHIP in both Lincoln and Omaha, I found it is cheaper to drive to Ames, IA than use the vets in Nebraska. There is now a vet in north-central Nebraska that is certified to perform PennHIP and the last time I was charged $200 for the exam, sedation, x-rays, and evaluation fee, this is extremely reasonable. The PennHIP web site can help you locate certified vets. The best thing to do is once you get some names is to contact them individually to see what they charge.
I also believe that people have more of a comfort level with OFA than PennHIP. Several years ago, I contacted both PennHip and OFA regarding the number of dogs in their databases. PennHIP responded and told me that as of September 2000 there were 29,479 dogs in their database. OFA sent me an E-mail stating there was 825,000 dogs their database. Please note that I did not inquiry as to the number of breed categories and/or the total number of dogs within any given breed category. I am sure this information is available and PennHIP would be more than willing to share this data if asked.
I think that PennHIP is still being viewed as the “new kid on the block” by some people. These same individuals want to look at more information to see if the PennHIP predictions regarding laxity and CHD are in true. There is a web site for PennHIP that has some very good information along with some frequently asked Q&A. The site address is: http://www.vet.upenn.edu/ResearchCenters/pennhip
I have a list of references regarding PennHIP if you are interested. It is too long to post here, but if you send me a PM, I will send you the list.
When I was doing research on PennHIP, I came across the following interview with Dr. Gail Smith, University of Pennsylvania. The interview occurred in June 1995. I am posting a few of the questions and Dr. Smith's responses. You can see the entire interview at http://bullmastiffinfo.tripod.com/pennhip1.html
I hope the following information helps answer some of your questions.
Question: Did that paper (referring to a 1989 research paper on examination of human infant hips where Dr. Corley with OFA raises the question that the examination procedure in the infant may actually cause a stable hip to become unstable) present any actual data documenting real harm done by the technique?
Dr. Smith: For the PennHIP procedure, the hips are placed in a neutral (stance-phase) position and a small harmless distractive force is applied to displace the femoral heads laterally from the acetabula. I am not aware of any such reports (studies that document harmful effects) and I am confident that if such documentation existed, it would have already been brought to the attention of the breeding public by the OFA. One should not lose sight of the fact that the OFA position is itself a stress-radiographic method that to my knowledge has not undergone safety testing. Also, it must be recognized that the PennHIP procedure specifies that an OFA radiograph be made for each compression and distraction view made (for a total of three views). After many studies and much close scrutiny of our data, we have no evidence to suggest that the procedure is any more harmful than the OFA stress-radiographic procedure.
Question: Do you think that the PennHIP procedure might cause an otherwise healthy adult dog, without CHD (canine hip dysplasia), to go on to develop joint disease? What about 4-6 month old puppies whose skeletal systems are not yet matured?
Dr. Smith: No. Not a single tight-hipped dog, irrespective of breed and age of first evaluation, has yet developed signs of DJD (degenerative joint disease) regardless of number of distraction procedures done throughout its lifetime. Longest follow-up is 9 years.
Question: What about a dog that has CHD, could it be worsened by the PennHIP exam?
Dr. Smith: Dogs with extant, clinically apparent disease can suffer transient discomfort stemming from any manipulation of the hip even routine orthopedic examinations.
Question: To the best of your knowledge, has anyone ever reported to you or to ICG (International Canine Genetics) that their dog developed hip problems as a result of the PennHIP procedure? If yes, how many such reports in how many years?
Dr. Smith: Of the more than 6,000 dogs evaluated thus far using the PennHIP procedure (3 radiographic views including the OFA view), fewer than 6 owners have reported that they thought the process may have cause temporary discomfort. No long-term complications have been reported. Could a dog that has no clinical symptoms of CHD, but has loose hips be at risk for harm from the exam? Dogs presenting without clinical signs are not made clinically painful in the short term by the evaluation procedure. In the long term, loose-hipped dogs having multiple PennHIP evaluations over their life appear to be no more at risk for developing osteoarthritis than those evaluated for the first time as an adult.
Question: In your opinion, is the PennHIP method any more or less risky to the dog than the positioning done for an OFA x-ray?
Dr. Smith: In my opinion, the distraction procedure is less painful than the OFA procedure. I feel neither procedure has measurable risk for ill effects to the dog.