A fourteen-year-old mongrel female dog that was 22 kg and had two large mammary tumor lesions was admitted to the Animal Teaching Hospital of Chonbuk National University. Two large mammary tumor lesions were observed in the right caudal thoracic and the left inguinal mammary glands, which were sized 6 cm and 5 cm in diameter, respectively. These tumor lesions were removed by block mastectomy, then large skin defect of 7 cm diameter in caudal abdominal wall were recoverd by classic Z-plasty in both medial thigh. Classic Z-plasty was designed with 60 in angle and, with 6 cm in length of central limb in right medial thigh and 4 cm in left, respectively. This patient had been recoverd to normal gait and behavior at 20 days after the plastic operation.