Hip scoring is done after the dog is 1 year old and is used to determine the degree of hip dysplasia. It is a scheme that was introduced in 1983 by the British Veterinary Association (BVA) and supported by the Kennel Club to examine the images of the dogs hips by assessing different areas of the joint and giving them an overall score.
The lower the score, the less the degree of dysplasia present. The minimum (best) score for each hip is zero, and the maximum (worst) is 53, giving a range for the total of 0 to 106. Each hip is scored separately under the BVA, so within the UK scores are usually displayed as two numbers separated by a forward slash (e.g. 2/6). Each of the nine criteria are scored out of 6 with exception of the Caudal Acetabular Edge which is a score out of five.
The British Veterinary Association uses the following criteria to determine hip score:
The Norburg Angle is angle formed by a line connecting the centres of both femoral heads (below left) and one drawn from the centre of the femoral head to the rim of the hip joint (the acetabular rim).
Subluxation - If the femoral head has subluxed from the joint (below right), it will substantially change the Norburg Angle.
Cranial Acetabular Edge - The acetabulum is the socket of the hip bone, into which the head of the femur (leg bone) fits. The cranial edge is the part closest to the head end.
Dorsal Acetabular Edge - this is the edge that you would find between the inside leg and the dogs stomach.
Cranial Effective Acetabular Rim - this is the the region where the dorsal acetabular edge curves around to become the cranial acetabular edge
Acetabular Fossa - is a roughly circular depression in the depth of the acetabulum and contains the origin of the teres (round) ligament, a short, strong band of tissue that attaches to the femoral head at a slightly flattened area, the fovea capitis.
Caudal Acetabular Edge - The caudal acetabular edge is shorter and less well defined than the cranial acetabular edge. Its medial end merges with the acetabular fossa. This is the part towards the dogs pelvis
Femoral Head/Neck Exostosis - The joint capsule is attached to the margin of the acetabulum and around the femoral neck. In the presence of hip laxity, the joint capsule is under abnormal tension and new bone is produced at its attachment to bone, particularly around the femoral neck Exostosis is a benign outgrowth of cartilaginous tissue on a bone.
Femoral Head Recontouring - When marked hip dysplasia is present, continued instability of the joint causes the femoral head to change its shape progressively, and any deviation from its normal shape is scored as recontouring (remodelling).
Below is the BVA guide to hip scoring