Classification of Angular Limb Deformities Affecting the Canine Radius and Ulna Using the Center of Rotation of Angulation Method.

OBJECTIVE: To classify the type of angular deformity affecting the radius and ulna in canine limbs using the center of rotation of angulation methodology. STUDY DESIGN: Retrospective case series. ANIMALS: Dogs (n=71) diagnosed with thoracic limb lameness attributable to antebrachial angular limb deformities. METHODS: Medical records from 2006-2013 were searched and cases with orthogonal radiographs or computed tomographic scans of the affected antebrachium were included. Classification of the deformity in the frontal plane and the presence of sagittal plane angulation, torsion, and adjacent joint radiographic disease were determined and compared. RESULTS: Chondrodystrophic (n=26; 44 limbs) and non-chondrodystrophic (n=45; 62 limbs) dogs were included. Thirty-five uniapical and 71 biapical or multiapical deformities in the frontal plane were identified. The incidence of biapical deformities was statistically higher in chondrodystrophic compared to non-chondrodystrophic dogs (P=.02). When breeds were combined, biapical deformities were associated with a significantly higher incidence of adjacent radiographic joint disease (P=.049), more frequently affecting the elbow (P=.022). Overall, 82% of the 106 limbs had radiographic evidence of either elbow or carpal joint disease at the time of presentation. CONCLUSION: Biapical deformities are common in dogs with limb deformities, particularly chondrodystrophic dogs. Radiographic evidence of disease in adjacent joints should be evaluated in patients presenting for antebrachial deformities.