Radiographic hip joint phenotype of the Pembroke Welsh Corgi

Abstract

The purpose of this prospective and retrospective cross-sectional study was to assess the radiographic hip joint phenotype of the Pembroke Welsh Corgi. Coxofemoral joints of 399 Corgis were evaluated by the PennHIP method and standard ventrodorsal hip-extended radiographs for subluxation, osteoarthritis (OA), caudolateral curvilinear osteophytes (CCO), and circumferential femoral head osteophytes (CFHO). Joint laxity was measured by distraction index (DI). Few Corgis showed conventional OA (6.8%) despite all Corgis having DI >0.30; 18% had subluxation, 22.3% had CCO, and 74.4% had CFHO. Higher DI increased the odds for subluxation but not for OA, CCO or CFHO. The presence of CCO increased the odds for OA by 4.6 times (p=0.002) and 2.2 times (p=0.01) for hip dysplasia. All dogs with OA had CFHO. The presence of CFHO increased the odds for subluxation 8.7 times (p<0.001) and 8.9 times (p<0.001) for hip dysplasia. Subluxation increased the odds for OA by 15.4 times (p<0.001). Corgis showed a low frequency of conventional OA despite having joint laxity that has been shown to correlate with hip OA and hip dysplasia in large breed dogs. The relationship between CCO and OA was similar to published findings in non-chondrodystrophic, large breed dogs and the CFHO was significantly associated with hip dysplasia in this breed. The CCO is a sign of OA and the CFHO is a marker for subluxation; both are phenotypic-markers for hip dysplasia in this chondrodystrophic breed. The data suggests that the CFHO is part of the disease phenotype and not normal for the breed.