So, what is PennHIP and why is it important?
There are two different tests (both based on X-rays of the hip) available for hip dysplasia: OFA and PennHIP.
The OFA hip laxity was developed in 1966, and is a subjective test scored on a rubric. PennHIP was established more recently in 1993, and is a direct objective measurement of hip laxity (how loose the thighbone is in the socket.) Breeders can have their dog’s hips checked through PennHIP as early as 16 weeks old. This allows for breeders to ensure the future of their breeding program is not in jeopardy. Although PennHIP can be completed early, the Golden Retriever Club of America's Code of Ethics requires all breeders to have PennHIP testing completed after each Golden Retriever reaches the breeding age of 24-months old.
PennHIP gives an estimate of the risk for painful osteoarthritis (OA) of canine hip dysplasia (CHD) later in life. The distraction index (DI) used in the PennHIP method serves as a measurement of passive hip laxity, the degree of looseness of the hip joint when the dog's hips are completely relaxed. The lower the DI number, the better. For breeding Retrievers, early detection of at-risk hips can allow the breeder to make early, informed decisions as to which dogs to keep in their breeding programs.
So, how did this all start?
In 1983, Dr. Gail Smith, a Professor at the University of Pennsylvania School of Veterinary Medicine, conceived and developed a new scientific method for the early diagnosis of CHD. Research conducted in his laboratory proved the diagnostic method to be capable of estimating the susceptibility for CHD in dogs as young as sixteen weeks of age. The distraction index (DI) used in the PennHIP method serves as a measurement of passive hip laxity, the degree of looseness of the hip joint when the dog's hips are completely relaxed. Dogs with a DI of 0.3 have tighter hips and are less likely to develop Degenerative Joint Disease (DJD), while those with looser hips whose DI values approach 0.7 or more are at greater risk. In 1993, Dr. Smith established PennHIP, a cooperative scientific initiative, to serve as a multi-center clinical trial of the new hip dysplasia diagnostic technology. In 2013 PennHIP was acquired from the University of Pennsylvania by ANTECH Diagnostics, Inc, of Los Angeles, CA.
So, why PennHIP over OFA hip testing?
The PennHIP x-ray method is unique for several reasons. First, it is a well-researched, objective method following strict scientific protocols and published in peer-reviewed veterinary literature. Second, the distraction index assigned to each hip joint is based on precise measurements and mathematical calculations. Dr. Smith and his colleagues feel this is superior to a subjective description of "shallow acetabulum" as found in an OFA report. Third, veterinarians who wish to submit films to PennHIP are required to be trained in the techniques and to be certified. This assures that standard protocols will be used in obtaining the films and helps ensure accurate data. While no one promises that the PennHIP method of measuring joint laxity will be 100% accurate in predicting which dogs will develop hip dysplasia, it is superior to any other available diagnostic method.
So what is Hip Dysplasia?
Hip Dysplasia is an arthritis-like disease which affects about half of golden retrievers, mostly the American Golden Retrievers (that's why we carefully select our English Golden Retrievers). Hip Dysplasia typically develops between 2 and 5 years of age, and causes intense pain while walking. The only cure is surgically replacing the hip, which is expensive and often results in reduced mobility. The good news is, it's mostly genetic. By carefully choosing our breeding retrievers, we can reduce the incidence of hip dysplasia dramatically. All our adults are hip certified dogs. This virtually guarantees our puppies to have hips that are above the breeding threshold and unlikely to ever develop hip dysplasia.
