A New Scientific Method for Early Screening for Canine Hip Dysplasia
Canine Hip Dysplasia (CHD) is the most common, heritable orthopedic problem seen in dogs. It affects virtually all breeds of dogs but is especially problematic in large and giant breeds. Clinically, the disease manifests itself in one of two ways: I ) a severe form that typically afflicts the younger animal and is usually characterized by marked pain and lameness, or 2) a more chronic form with more gradual onset of clinical signs such as mild, intermittent pain, stiffness and restricted range of motion in the hips as the dog ages. In many cases, the chronic form may be clinically silent.
Breeders and veterinarians have long sought a reliable method to accurately appraise the likelihood of a dog developing CHD and passing that genetic trait to any offspring. It was generally recognized that the current diagnostic methods of hip evaluation were associated with disappointing progress in reducing the frequency of CHD. In 1983, Dr. Gail Smith from the University of Pennsylvania School of Veterinary Medicine began to actively research and develop a new scientific method for the early diagnosis of Canine Hip Dysplasia. Research in his laboratory resulted in a diagnostic method capable of estimating the susceptibility for CHD in dogs as young as 16 weeks. The method has shown distinct advantages over the standard CHD diagnostic method that evaluates dogs at 2 years or older. The University of Pennsylvania Hip Improvement Program (PennHIP) was founded as an extension of Dr. Smith's laboratory research. Below are answers to some commonly asked questions about the PennHIP method.
What Exactly Is PennHIP?
PennHIP is a scientific method to evaluate a dog for Hip Dysplasia. The radiographic procedure involves a special positioning of the dog so that the dog'spassive hip laxity can be accurately measured. In simple terms, passive hip laxity refers to the degree of "looseness" of the hip ball in the hip socket when the dog's muscles are completely relaxed. Research has shown that the degree of passive hip laxity is an important factor in determining susceptibility to develop Degenerative Joint Disease (DJD) later in life. Hip DJD, also known as osteoarthritis, is the universally accepted confirmation of CHD.
How Was PennHIP Developed?
The development of PennHIP has involved multiple disciplines including biomechanics, clinical medicine, radiology, population genetics and associated statistical analysis. The first phase of development involved sophisticated testing to determine the optimal patient position for measuring hip laxity. Subsequent research confirmed that hip laxity was the primary component in the development of hip dysplasia and that by appropriately measuring passive hip laxity was then possible to identify dogs at risk to develop CHD. In addition, the procedure was shown to be accurate on puppies as young as 16 weeks of age. None of the other methods used to evaluate for CHD has undergone similar rigorous testing through controlled scientific studies to determine their accuracy.
How Does PennHIP Differ from the OFA?
PennHIP differs in some very fundamental and important ways. First, PennHIP was developed and tested following strict scientific protocol. It was mandatory that there be scientific confirmation that the technology would provide earlier and more accurate disease diagnosis. More than a decade of research and analysis have confirmed PennHIP's effectiveness. As with all diagnostic tests, PennHIP's accuracy is not 100%, but it is far superior to any other available diagnostic methods. Second, passive hip laxity is objectively measured and the resulting Hip Evaluation Report is not issued in a pass/fail framework. PennHIP is specifically measuring passive joint laxity and includes the quantitative measurement in its report. Based on the degree of laxity, the individual dog is then ranked relative to other members of the same breed. This allows breeders to easily identify those animals with tighter hips. These dogs are less likely to develop CHD and pass that genetic tendency on to future generations. Third, because PennHIP is measuring passive hip laxity, the position of the patient is very different from the hip extended position used by OFA. The hip extended position is a useful radiographic view to screen the dog for existing hip disease, but its predictive value for CHD has never been proven. Ironically, the biomechanics of the hip extended position are such that the radiograph may actually give a false impression of joint tightness. Fourth. the PennHIP method is based on strict quality control. To take PennHIP radiographs. veterinarians must undergo training and a certification process to demonstrate competency. The data generated from PennHIP undergoes continual review and statistical analysis so that useful information, by breed, is available to judge progress toward reducing CHD. For optimal validity, it is mandatory that all radiographs by PennHIP veterinarians be submitted for analysis and inclusion in the PennHIP database. This policy eliminates the practice of "prescreening" radiographs and sending only the "best" for evaluation, resulting in biased hip data for any given breed.
What Happens to My Dog During a PennHIP Evaluation?
To obtain diagnostic radiographs, it is important that the patient and the surrounding hip musculature be completely relaxed. For the comfort and safety of the animal, this requires sedation, however some veterinarians prefer general anesthesia. Typically three separate radiographs are made during an evaluation. The first is a compression view where the hips are pushed into the socket. This helps show the true depth of the hip socket and gives an indication of the "fit" of the ball in the socket. A distraction view is then taken utilizing a special positioning device. This position is the most accurate one for showing the degree of passive laxity. Passive laxity has been shown to correlate with the susceptibility to develop DJD. A hip extended view is also included for the sole purpose of examining for any existing joint disease such as arthritis. The PennHIP procedure has been safely performed on thousands of patients.
What Is the Cost of Having My Dog Evaluated?
The total fee for a PennHIP evaluation is determined by the veterinarian providing the service. It is important to remember that the total service typically includes sedation/anesthesia, 3 radiographs, office consultation and all charges associated with mailing and film evaluation. You will not find it necessary to write a separate check for evaluation fees or mail your dog's films. The film evaluation charge will be included in the total cost of a PennHIP evaluation.
Is PennHIP Going To Replace OFA?
As technology advances, the veterinary professional community will offer and utilize improved methods of disease diagnosis. The dog breeding community will also endorse those methods that help them achieve their goals of reducing the frequency of hip dysplasia in dogs while maintaining other desirable traits and features. The PennHIP technology and research have been and will continue to be fully presented to the veterinary medical community for its review. PennHIP has been received enthusiastically as a major step toward reducing the frequency of CHD. We encourage and welcome continued scientific examination and comparison of PennHIP to any available methods of canine hip evaluation.
Will AKC and Other Breed Registration Organizations "Recognize" PennHIP?
ICG will be working with many organizations to present the PennHIP technology and the positive impact it holds for reducing Canine Hip Dysplasia. It is conceivable that at some point a PennHIP reference might be included as part of the dog's registry information. However, all hip evaluation reports are considered confidential medical information and are released only to the PennHIP veterinarian and the owner of the dog (unless the owner requests otherwise).
How Does This Benefit Me as an Owner or Breeder of Dogs?
Scientific data confirms that the PennHIP method surpasses other diagnostic methods in the ability to accurately predict susceptibility to developing CHD. The method can be performed on dogs as young as sixteen weeks of age compared with two years using the standard technique. The ability to receive an early estimate of a dog's hip integrity is important whether the dog is intended for breeding, working or a family pet. The data generated by PennHIP will allow breeders to confidently identify the members of their breeding stock with the tightest hips. The PennHIP interpretation will also permit breeders to assess the progress they are making with their breeding program as they strive to reduce the amount of hip laxity in their dogs.
How Can I Get the Name of a PennHIP Veterinarian?
To obtain the name of a veterinarian near you who is trained and certified to perform the PennHIP procedure, call ICG at 1-800-248-8099. If there is not a veterinarian near you presently, additional veterinarians are being trained throughout the country. If your veterinarian would like to learn more about PennHIP, please have him/her contact ICG directly.