Quantitative assessment of hip morphology to enhance the identification of hip dysplasia in German Shepherd Dogs

Abstract

OBJECTIVE To develop quantitative measures that, when combined with the Fédération Cynologique Internationale (FCI) score, would potentially enhance the accuracy of the scoring process. ANIMALS 153 client-owned purebred German Shepherd Dogs with normal and near normal (71 dogs) and dysplastic coxofemoral joint (82 dogs). PROCEDURES Center edge (CE) angle, Norberg angle (NA), indexes of dorsal acetabular femoral head (AFH) coverage width and area, acetabular index angle, and inclination angle were determined. We also investigated the correlation between selected variables. Coxofemoral joints were classified into normal, near normal, and mildly, moderately, and severely dysplastic joints based on the morphometric criteria previously established by the conventional FCI scoring. Variables were compared among the 5 groups using ANOVA. Linear relationships were determined using Spearman correlation coefficients. RESULTS All radiographic measurements differed significantly (P < .0001) among the 5 assigned groups (normal, near normal, mildly dysplastic, moderately dysplastic, and severely dysplastic hip joints). NA was the only measure that differed significantly (P ≤ .03) between the 5 assigned groups. Positive correlations were identified between Norberg and CE angles (rs = 0.93), between width and area indexes of dorsal AFH coverage (rs = 0.92), and between the measurement techniques utilized to assess lateral versus dorsal AFH coverage (rs ≥ 0.65). CLINICAL RELEVANCE Evaluation of lateral and dorsal AFH coverage may help to refine the scoring system used to select German Shepherd Dogs for breeding. German Shepherd Dogs with NA < 103°, CE angle < 20.8°, dorsal AFH coverage width index ≤ 49%, and/or dorsal AFH coverage area index ≤ 51% should be considered to have mild, moderate, or severe hip dysplasia and are therefore not good candidates for breeding. Borderline values between near normal and mildly dysplastic joints should be reevaluated.