Dogs with hip dysplasia appear to be born with normal hips and then to develop the disease later. This has led to a lot of speculation as to the contributing factors which may be involved with this disease. This is an inherited condition, but not all dogs with the genetic tendency, will develop clinical signs and the degree of hip dysplasia which develops, does not alway seem to correlate well with expectations based on the parent's condition. Multiple genetic factors are involved and environmental factors also play a role in determining the degree of hip dysplasia. Dogs with no genetic predisposition do not develop hip dysplasia.

If clinical signs of hip dysplasia occur in young dogs, such as lameness, difficulty standing or walking after getting up, decreased activity or a bunny-hop gait, it is often possible to help them medically or surgically. X-ray confirmation of the presence of hip dysplasia prior to treatment is necessary.

There are two techniques currently used to detect hip dysplasia, the standard view used in Orthopedic Foundation for Animals (OFA) testing and X-rays (radiographs) utilizing a device to exaggerate joint laxity developed by the University of Pennsylvania Hip Improvement Program (PennHIP Link). The Penn Hip radiographs appear to be a better method for judging hip dysplasia early in puppies, with one study showing good predictability for hip dysplasia in puppies exhibiting joint laxity at 4 months of age, based on PennHIP radiographs.



To position a dog for an OFA film the dog is rolled onto its back and then the rear legs are stretched out straight and the stifles (knees) turned in so that they are parallel with the kneecap centered in the patellar groove. The legs usually have to be pressed down toward the table to keep them both straight and parallel. This full extension of the hip is painful for a dog that has hip dysplasia and probably uncomfortable even for a normal dog.

Why is anesthesia required in order to have the dog radiographed? To have an x-ray that yields the information you're trying to discover the dog must be perfectly relaxed. Because the position required to take a diagnostic x-ray is a somewhat unnatural one, even very gentle, cooperative dogs cannot relax enough to be x-rayed properly.

The importance of radiography cannot be overstated. It can be done early, say five or six months of age, if dysplasia is suspected. If the results are questionable, reserve breeding until a time, when the x-rays are conclusive. Generally, by the time the dog is full grown, the x-rays will properly reveal the status of the hips. The OFA will not classify hips in dogs until they are two years of age.

The phenotypic evaluation of hips done by the Orthopedic Foundation for Animals falls into seven different categories. Those categories are normal (Excellent, Good, Fair), Borderline, and dysplastic (Mild, Moderate, Severe).

The hip grades of excellent, good and fair are within normal limits and are given OFA numbers. This information is accepted by AKC on dogs with permanent identification (tattoo, microchip) and is in the public domain.

Radiographs of borderline, mild, moderate and severely dysplastic hip grades are reviewed by the OFA radiologist and a radiographic report is generated documenting the abnormal radiographic findings. Unless the owner has chosen the open database, dysplastic hip grades are not in the public domain.

Other Hip Dysplasia Registries—A Comparison

Source:OFA