Multivariate Analysis of Morphometric Characteristics to Evaluate Risk Factors for Cranial Cruciate Ligament Deficiency in Labrador Retrievers

Abstract

To determine the combination of conformation characteristics of the pelvic limbs of Labrador Retrievers that best discriminates between limb at risk to develop cranial cruciate ligament (CCL) disease and limbs at low risk using radiographs, computerized tomography (CT) images, and dual-energy X-ray absorptiometry (DEXA). Cross-sectional clinical study. Twelve clinically normal and 9 unilaterally CCL-deficient Labrador Retrievers. The pelvic limbs of normal dogs were considered as non-predisposed to CCL disease and the contralateral limbs of CCL-deficient dogs as predisposed. Conformation variables, obtained from femur and tibial radiographs, pelvic limb CT images and DEXA studies, of predisposed pelvic limbs were compared with the conformation variables from pelvic limbs of the low-risk group. An ROC curve analysis was used to assess the discriminating properties of conformation variables for several combinations. We determined that a combination of tibial plateau angle (TPA) and femoral anteversion angle (FAA) measured on radiographs was optimal for discriminating predisposed and non-predisposed limbs for CCL disease in Labrador Retrievers. Assessing predisposition to CCL disease with a combination of conformational measurements is better than using univariate parameters. In the future, TPA and FAA may be used to screen dogs suspected of being susceptible to CCL disease.