A male, 11-month-old, Shih-tzu dog weighing 5.2kg showing knuckling secondary to severe cranial bowing of left antebrachium with valgus deformity of the carpus was presented to the Veterinary Medicine Teaching Hospital of Seoul National University. Radiographic findings were a premature closure of the distal ulnar physis, a cranial bowing of the radius, subluxation of the elbow joint, and degenerative changes in the carpal joint. The patient was treated by performing an oblique osteotomy of the radius and ulna, followed by application of External Skeletal Fixations. At 18 weeks postoperatively, the radius was healed. An incongruency of the elbow joint and radial angular deformity was corrected.