Penn HIP (Hip Improvement Program) Radiography

As stated in a previous article, canine hip dysplasia (CHD) is the most common inherited orthopedic abnormality seen by veterinarians in dogs. It can affect any purebred or mixed-breed dog, but is mostly diagnosed in large and giant breeds. It will typically manifest itself in two forms: 1) young dogs with noticeable lameness and pain, or 2) adult dogs that have a chronic form with a more gradual onset and varying degrees of lameness, stiffness and pain.

We realize the prevalence of CHD and how devastating it can be to our patients. We became more and more frustrated by the traditional means of evaluating breeding dogs for hip dysplasia, which is the hip-extended radiographic view that is evaluated by the Orthopedic Foundation for Animals (OFA). We found that we were seeing many young and old dogs with hip dysplasia that were born from “OFA certified” breeding dogs. This led us to question the reliability of the OFA technique and the subjective means they used to interpret radiographs. In 1994 a client who was a Golden Retriever breeder, recommended we look into becoming trained and certified to take Penn HIP radiographs. After thoroughly researching Penn HIP, we became very impressed with the results of their data. We realized that Penn HIP provided us with a means to more accurately evaluate the susceptibility of my canine patients to CHD. We realized that it had significant applications for not only breeding, but non-breeding family dogs as well.

What is Penn HIP? Penn HIP is an objective scientific method of evaluating a dog’s susceptibility for developing CHD. Its development began in 1983 by Dr. Gail Smith, a veterinary orthopedic surgeon at the University of Pennsylvania School of Veterinary Medicine. Rather than one radiograph, Penn HIP requires three differently positioned views that measure the dog’s passive hip laxity. Passive hip laxity is essentially the amount of looseness of the hip ball in the hip socket. Dr. Smith’s research has shown that the degree of hip laxity, as measured by the Penn HIP technique, is the most important risk factor in determining whether a dog is prone to developing CHD.

How is Penn HIP performed? As stated above, Penn HIP involves taking three different radiographs of the patient’s hips. It requires that the dog be completely relaxed. Therefore, sedation or general anesthesia is required. After the radiographs are developed, they are submitted to Penn HIP for evaluation. The owner and the veterinarian then receive the dog’s Hip Evaluation Report in the mail within 10-14 days. This report indicates the patient’s distraction index (DI), which is the measure of passive hip laxity. It also indicates the dog’s Hip Laxity Profile and what percentile the dog falls in for its individual breed. Though somewhat involved, the report gives the pet owner and veterinarian a wealth of information for evaluating the orthopedic health of the dog.

How is Penn HIP different from OFA? As stated above, Penn HIP requires three, not one, radiographic views that follow a strict scientific protocol. The results are objectively evaluated and frequently published in peer reviewed veterinary journals. Penn HIP follows strict quality control. Penn HIP certified veterinarians must go through a training and certification process to demonstrate competency in the technique. No training or certification is required by OFA. Penn HIP also requires that all Penn HIP radiographs be submitted for evaluation. This prevents “prescreening” radiographs and submitting only the best patient films, which is unfortunately a common practice by many veterinarians and breeders with OFA radiographs. Prescreening is not only of questionable ethics, but also serves to obscure the OFA data pool for individual breeds.

How does Penn HIP benefit non-breeding dog owners and breeders? Penn HIP can be performed on dogs as young as 16 weeks of age, whereas OFA cannot be performed until two years of age. We feel that it is very important to have an early evaluation of a dog’s hips, regardless of whether they are intended to be used for breeding or as a spayed or neutered family pet. In fact, most of the Penn HIP procedures that we perform are at the same time as the dog’s spay or neuter surgery. This allows the dog owner to evaluate their pet’s risk of developing CHD and, if needed, choose a course of therapy with their veterinarian that will hopefully improve their dog’s quality of life. For breeders, Penn HIP allows them to choose dogs for breeding that have the tightest hips and are less likely to pass on CHD. It also allows them to evaluate the progress of their breeding programs in improving their hip evaluation reports.

Though Penn HIP has obvious benefits for non-breeding dogs, if we are to see a significant decrease in CHD in the canine population it must start with breeders. Penn HIP is already recognized by the American Kennel Club. It is gaining more and more acceptance from breeding circles, not just in the United States, but in many foreign countries as well. Hopefully, with the new millennium upon us, some day soon canine hip dysplasia will cease to be a common disease and be looked upon as a rarity.


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