The focus of this study was to calculate the diagnostic validity of the FCI (Fédération Cynologique Internationale) method and the Swiss scheme, the repeatability of the individual criteria and final diagnostic findings of one assessor (intra-observer agreement) as well as the accordance of all findings obtained by two independent assessors (inter-observer agreement) with differing degrees of experience. The study involved the examination of a total of 180 dogs of six different breeds (30 dogs of each breed): Rottweiler, Golden Retriever, Hovawart, German Wirehaired Pointer, German Shorthaired Pointer and Beagle. Both diagnostic methods exhibit a very high sensitivity (100%) and a very low specificity (5,3-54,8%) and appeared well suited for discovering animals not being free of HD. HD-suspected dogs could be better recognized by using the Swiss scheme. The intra-observer agreement, when using both methods, was in accordance at an average of 60%, which was significantly higher than the inter-observer agreement (24%). Both approaches showed a good repeatability of the Norberg angle, the position of the femoral head centre (FHC) in relation to the dorsal acetabular rim, the craniolateral acetabular rim and the Morgan line. When assessing individual breeds, FHC was the only criterion that was well reproducible in all breeds. The inter-observer agreement was mostly well regarding the Morgan line and the depth of the acetabulum. The specific analysis of the results revealed how far the evaluation and interpretation of HD-radiographs can be influenced by the individual radiologic education and experience of the assessor. Minimal displacements and asymmetries of the hip could falsly let appear malformities of the acetabulum (depth, shape of the craniolateral and cranial rim), the articular gap and the Norberg angle.
Femurs held in an abducted position can produce the impression of a shortened femoral collar. Areas of relevant higher densitiy distal of the closed epiphysical gap of the femoral head and an eventually recognizable physiologic bone-crest, radiologically apparent as a fine shadowing line on the caudal side of the femoral collar, can be interpreted as osteoarthritic appearances. An insufficient consideration of these placement-caused pseudo-anomalies in this study lead to inequalities in the final assessment of two assessors with different radiologic experience of one to two HD-degrees in all breeds.
hip dysplasia / FCI grading system / scoring scheme developed by Flückiger / dog / beagles