Evaluation of a scoring system based on conformation factors to predict cranial cruciate ligament disease in Labrador...

To determine the association of a radiographic score derived from tibial plateau angle (TPA) and femoral anteversion (FAA) with an outcome of cranial cruciate ligament deficiency (CCLD) in large dogs.

Cross-sectional study.

167 Labrador Retrievers.

Hind limbs of sound Labrador Retrievers over 6 years of age were considered at low risk for CCLD. Limbs were considered high risk for CCLD if they were affected or predisposed (sound contralateral limb in dogs with unilateral CCLD). The radiographic CCLD score was calculated for each limb. The TPA, FAA, and CCLD scores were compared between limbs of the same dog and between risk categories. A contingency table was used to evaluate the association of the CCLD score with the CCLD status of limbs.

TPA, FAA, and CCLD scores were greater in limbs categorized as high risk for CCLD than in normal limbs. The sensitivity and specificity of the CCLD score was 87% and 79%, respectively. The positive predictive value was 69% and the negative predictive value was 92%. Scores were similar between paired right and left limbs, but did not agree for predicted status in 14/106 dogs.

Our study supports an association between TPA, FAA, and CCLD in Labrador Retrievers. The negative predictive value of the CCLD score supports its application for screening dogs considered at low risk for CCLD. Positive CCLD scores should be interpreted with caution and the status of a dog may be undetermined if scores obtained on each limb disagree.