Assessment of New Radiographic Traits in Canine Hip Dysplasia (CHD)

Canine hip dysplasia (CHD) is a polygenic, multifactorial developmental disorder of the hip joint. Hip laxity, an early characteristic of CHD, leads to degeneration within the joint due to mechanical injury. Definitive diagnosis can be achieved by x-ray examination. The aim of our study is to refine CHD assessments using a quantitative planimetry method. The measurement of the Norberg angle (NA) was found subjective and insufficient to measure hip laxity on the standard ventrodorsal projection, because extension of the pelvic limbs stretches the joint capsule and supports joint congruence. Therefore, we have decided to verify other methods of detecting CHD, which include measurement of femoral head coverage (linear and area coverage) and congruence angle (AoC). These parameters could provide us with relevant information about how well the head of the femur fits into the acetabulum and thus might help to assess CHD better, and identify affected individuals better. In our study, we included 122 x-ray images of 3 breeds of dogs of both sexes and at different ages 5.6 ± 1.8 years. The highest correlation was between both femoral head linear and both area overlap for Bavarian hounds. For Bernese mountain dogs it was between right NA and linear and area femoral overlap, between both femoral head linear and both area overlap. For German shepherd dogs it was found between both NA, between right NA and right AoC, between both AoC, between both NA with both femoral overlap and between both AoC and both femoral overlap on the same side.