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: 1) a severe form that typically affects the younger animal and is usually characterized by marked pain or 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.
Dog owners and veterinarians have long sought a reliable method to accurately predict the likelihood of a dog developing CHD and passing that genetic trait to any offspring. It was generally recognized that traditional diagnostic methods of hip evaluation were associated with disappointing progress in reducing the frequency of CHD. The PennHIP method was developed to address this problem.
PennHIP is a scientific method to evaluate a dog for Hip Dysplasia. 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. This research resulted in a diagnostic method of estimating susceptibility in dogs as young as sixteen weeks. This method has shown distinct advantages over other diagnostic methods that recommend final evaluation be performed when the dog is over two years of age or older.
In the traditional, hip extended position [for X-Rays], joint laxity is not clearly evident. (This position may actually give a false impression of joint tightness,) While the view is accurate in detecting existing arthritic changes, there is no scientific data to show that the view can reliably distinguish between "normal" and disease susceptible dogs when arthritic changes are not present.
The "distraction" view of the same dog reveals a much greater amount of joint laxity. Controlled scientific studies have proven that dogs which carry a significant risk of developing joint disease can be diagnosed despite having been classified as "normal" by the traditional method.
The radiographic procedure involves a special positioning of the dog so the dog's passive 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 the susceptibility to developing Degenerative Joint Disease (DJD) later in life. Radiographic hip DJD, also known as osteoarthritis, is generally accepted as confirmation of CHD.
To obtain diagnostic radiographs, it is important that the patient and the surrounding hip musculature to be completely relaxed. For the comfort and safety of the dog, this requires deep sedation, or based on your veterinarian's preference, general anesthesia. Typically, three separate radiographs are made during an evaluation.
The total fee for PennHIP evaluation is determined by the veterinarian providing the service. It is important to remember that the total service typically includes sedation/anesthesia, three radiographs, office consultation and all charges associated with mailing and film evaluation.
The PennHIP evaluation results in a confidential report to the owner indicating the dog's distraction Index (DI). The DI is a measure of passive hip laxity and is expressed as a number between 0 and 1. (A DI near 0 would indicate no joint laxity and very tight hips. A DI closer to 1 would indicate a high degree of laxity and very loose hips.)
Multiple investigations have confirmed that dogs with tighter hips are less likely to develop joint disease (CHD) than their counterparts with loose hips. In fact, in those breeds of dogs investigated at the University of Pennsylvania, a "threshold" level of tightness has been identified, below which the Hip Dysplasia is not found. In the future, we anticipate the PennHIP data to provide for each individual breed of dog. This profile defines the expected range of laxity within each breed and, when combined with DJD, it permits determination of Hip Dysplasia susceptibility as a function of hip laxity.
Benefits of PennHIP
The PennHIP method can be performed on dogs as young as sixteen weeks, compared with two years of age using the standard technique. An early estimate of a dog's hip integrity is invaluable, whether the dog's intended purpose will be for breeding, for working, or as a family pet.
For the breeder, the information compiled in the PennHIP database permits informed selection of breeding stock based on hip tightness relative to other members of the same breed. Studies show that the selection process for tighter hips can be imposed without sacrificing other desirable traits.
For the pet owner, the ability to identify your pet's susceptibility to develop DJD will allow you and your veterinarian to plan lifestyle adjustments to minimize disease expression if necessary.
For everyone, breeders and pet owners alike, the PennHIP method offers an accurate and early appraisal of passive hip laxity. Your certified PennHIP veterinarian will be happy to discuss the procedure with you.