Canine Hip Dysplasia
Canine Hip Dysplasia (CHD) is the most common, heritable orthopedic problem seen in dogs. It afflicts 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 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.
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 the 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 Dyslplasia. This research resulted in a diagnostic method capable of estimating the susceptibility of CHD in dogs as young as sixteen weeks. The method has shown distinct advantages over other diagnostic methods that recommend final evaluation be performed when the dog is two years of age or older.
Radiographic Techniques
In the traditional hip extended position, 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.
Procedure
The radiographic procedure involves a special positioning of the dog so that 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 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 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 a 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.
PennHIP is a safe procedure. Dogs with existing joint disease at the time of evaluation, may experience some transient discomfort following any orthopedic exam. Thousands of dogs have been PennHIP evaluated, and not a single tight-hipped dog, irrespective of breed and age, has developed signs of Degenerative Joint Disease (hip dysplasia), as a result of the evaluation.
Distraction Index
A 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 Hip Dysplasia is not found. PennHIP data provides a profile for each individual breed of dog. This profile defines the expected range of laxity within each breed and, when combined with the radiographic evidence of DJD, it permits determination of Hip Dysplasia susceptibility as a function of hip laxity.
Over 165 breeds are represented in the PennHIP database. Interest in this quantitative method to accurately assess the susceptibility of a dog to develop hip arthritis is growing rapidly. PennHIP has received international acceptance, and is the official hip evaluation system of the Japan Kennel Club. PennHIP evaluations are recognized by the American Kennel Club, and in the future, DI information will be included in the AKC’s Information and Health Database.
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 more information or the name of a PennHIP veterinarian near you, Call 1-800-248-8099, or visit them on the Internet at:
GDC (Institute for Genetic Desease Control) - Database that maintains information on genetic health of some lines for hips, elbows, stifles, and others.
OFA (Orthopedic Foundation for Animals) - Database that lists individuals that have passed for hips and elbows.