Association between body weight and hip dysplasia screening results in young adult dogs of different breeds in Sweden.

Canine hip dysplasia (HD) is a common developmental orthopaedic disorder with substantial impact on health and life expectancy. Body weight has been considered an important factor for the development, but prior studies evaluating this association on a large data set, strictly collected and without preselection of screening results, are lacking. The objectives of the study were to investigate a potential association between body weight and radiographic HD screening grade in young adult dogs of different breeds, and to study potential breed differences in selected breeds of different sizes. A cross-sectional study using hip screening results and body weight data from the Swedish Kennel Club, collected during 2007-2016 from 114,568 young adult dogs of 72 different breeds in Sweden, was performed. An association between HD screening grade and body weight was found; higher body weight within breed was associated with a more severe HD grade. The association was breed-dependent and significant in 13 of the 21 breeds included in the analysis on breed differences. In conclusion, higher body weight within breed was significantly associated with a more severe HD screening grade, and the association was breed dependent. This indicates that lower body weight might be a protective factor for developing HD.