Hip Dysplasia
I have a Golden Retriever. I know they can have hip problems. I have heard that there is a new test that predicts if a dog will be affected. How does it work?
You are referring to Canine Hip Dysplasia (CHD), the most common heritable orthopedic problem seen in dogs. It affects virtually all breeds, but is especially problematic in large and giant breeds. It appears (1) in a severe form that typically afflicts young animals and causes pain and lameness, or (2) in a more chronic form with a gradual onset of signs such as mild, intermittent pain, stiffness and restricted range of motion in the hips as the dog ages.
Dog owners and veterinarians have long sought a reliable method to more accurately predict the likelihood of a dog developing CHD and passing that genetic trait to any offspring. The new process that you are referring to more accurately identifies a dog, as young as 16 weeks, that will develop CHD. It is the PennHIP method which was developed at the University of Pennsylvania School of Veterinary Medicine. Traditionally radiographs were taken with the hip extended, a position that did not clearly show hip laxity or provide reliable data to identify disease susceptible dogs. In the PennHIP radiographic procedure, the dog is positioned so its passive hip laxity can be accurately measured. 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. This laxity is an important factor in determining susceptibility to developing degenerative joint disease (DJD) later in life. Radiographic hip DJD, also know as osteoarthritis, is generally accepted as confirmation of CHD.
For the diagnostic radiographs, it is important for the patient and hip area to be completely relaxed, so sedation or general anesthesia may be used. Typically, three separate radiographs are made during an evaluation. Results are given to a dog’s owner in a confidential report indicating the Distraction Index (DI). The DI measures the passive hip laxity expressed as a number between 0 and 1. (A DI near 0 indicates no joint laxity and very tight hips. A DI closer to 1 indicates a high degree of laxity and very loose hips.) Dogs with tighter hips are less likely to develop joint disease than their counterparts with loose hips. A study of evaluation data has determined a threshold level of tightness. No Hip Dysplasia has been found when scores are below that threshold. There is a safe range of DI scores for each of 165 breeds of dogs. The breed profile combined with the radiographic evidence of DJD permits determination of Hip Dysplasia susceptibility as a function of hip laxity.
The PennHIP evaluation method is being widely accepted and, in the future, will be included in the American Kennel Club’s information and health database. Tests can be performed on dogs as young as 16 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 is intended for breeding, working or as a family pet.
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