Limb-sparing surgery aims to provide a functional pain free leg for the patient after removal of a local tumour in the leg. Reasons to perform limb-sparing instead of amputation can be arthrosis or hipdysplasia or other problems with the locomotor apparatus that makes the patient unsuitable for amputataion. Owner reluctance to amputate is another reason for limb-sparing. This master?s thesis is a case study of a dog with an osteosarcoma in its distal radius. The dog was treated by a limb-sparing method that uses the ipsilateral ulna as a vascularized roll-over Autograft.