Thus, the chances of a dog developing hip dysplasia are decreased by selective breeding of parents without the genetic tendency for hip dysplasia, and by changing the nutrition of the growing dog. Selective breeding is enhanced by performing predictive tests such as OFA certification or the PennHipR score. Overall protein levels, vitamin C intake, vitamin D intake and other nutritional factors have no known effect, either positive or negative, on development of hip dysplasia. Hip dysplasia is initiated as a disparity between primary muscle mass and disproportionately rapid skeletal growth. Bone changes such as thickened femoral neck, bone spur formation, or sclerosis of the acetabulum occur secondarily to the poor fit of the hip joint.
Lameness is especially evident after exercise periods.
Young dysplastic dogs often lay on their belly with limbs outstretched behind them. Pain is often elicited during full extension of the joint by a veterinarian. Hip dysplasia is not generally an acute lameness, but one of slow progression of lameness severity. The diagnosis of hip dysplasia is suspected based on findings of hip laxity in young animals and pain on hip palpation in older animals, and confirmed by radiographs of the hip. Absence of the Ortolani sign indicates a normal hip or advanced degenerative joint disease precluding movement of the femoral head out of the acetabulum.