comparison to the qualitative methods. The quantitative measure is called the distraction index (DI) which is the measurement of the maximal femoral head displacement from the acetabulum. It is calculated by dividing the distance between the geometric centre of the femoral head and the geometric centre of the acetabulum by the radius of the femoral head. The degree of presence of osteoarthritis increases as the DI value go over 0.3, meaning that the dog is in a higher risk of developing the condition. Alternatives Norberg angle (NA): which measures the femoral head displacement from the acetabulum. It is calculated by drawing a line that connects between two dots that are located at the centre of each femoral head centre and another line that connects one of the first dots to the craniolateral acetabular rim on the same femoral head. A normal NA is ≥105 degrees. Percentage of femoral head coverage (%FHC): it measures the femoral head displacement from the acetabulum. The percent is considered normal or concluding that the dog has a good hip joint congruity when the percent is ≥50% coverage. Dorsolateral hip testing using radiography and CT: dog is in sternal recumbency position and kneeling. Pelvic stress radiography: dog is in dorsal recumbency position, femur is in 60° angle while the vet is manually pushing it in a craniodorsal direction. Drawbacks The technique can only be performed by a certified veterinarian or vet technician as they must take certain training course and they have to submit trial radiographs that shows their level of proficiency to get their certificate approved. Not recognized by the American Kennel Club Requires anesthesia. Higher cost compared to the alternatives that ranges between $200-400. See also Orthopedic Foundation for Animals References External links Dog health