The Orthopedic Foundation for Animals (OFA) grades hips for the presence of hip dysplasia, a malformation of the hip joint that can result in mobility limitations, lameness and arthritis. OFA ratings fall into seven categories and are based on evaluation of X-rays by three independent radiologists.
OFA grades of excellent, good and fair are considered normal while grades of mild, moderate and severe indicate corresponding levels of hip dysplasia. Borderline hips are those that are not normal but are not clearly dysplastic. Factors considered in the rating include the conformation of the hip socket and the femoral ball, the fit of the femoral ball into the hip socket and the amount of space within the joint.