Evaluation of risk factors for degenerative joint disease associated with hip dysplasia in dogs.

Passive coxofemoral joint laxity of dogs, as quantitated by a distraction-stress radiographic method, may have important prognostic value in determining susceptibility to hip dysplasia. Data from 151 dogs, representing 13 breeds, were included in a logistic regression model to evaluate the contribution of factors such as age, breed, weight, sex, distraction index, and Norberg angle to the risk of developing degenerative joint disease (DJD) of the coxofemoral joint. Of the factors studied, the amount of passive hip laxity, as quantitated by the distraction index, was the most significant (P < 0.0001) determinant of the risk to develop DJD of the coxofemoral joint. In the longitudinal and cross-sectional components of the study, distraction index was a significant (P < 0.001) risk factor for DJD, irrespective of age at evaluation (4, 12, or 24 months). The strength of the hip laxity:DJD correlation increased with the age of dog. In contrast, the Norberg angle, a measure of hip laxity on the standard hip-extended radiograph, was not found to be a significant risk factor for DJD, either in the longitudinal or cross-sectional analyses. Breed-specific probability curves of DJD susceptibility indicated that German Shepherd Dogs had a significantly (P < 0.05) greater risk of developing DJD than did the pool of non-German Shepherd Dogs. The information derived from this statistical model will help to scientifically characterize the role of passive hip laxity as a component in the pathogenesis of DJD of the coxofemoral joint.