A 10-year-old female Rottweiler was referred to the clinic of the Department of Surgery, Veterinary Faculty of Istanbul University with a history of spontoneus fracture in the right hind limb. Radiographical examinations showed proliferative bone tissue, osteoporosis and fracture in the distal part of the femur. An osteolytic malignant tumor was suspected. The affected hind limb was amputated and was presented to the department of the Pathology for histological examination. Histopathologically, the dog was diagnosed with telangiectatic osteosarcoma of the femur. The purpose of this study is to present clinical and histopathological features of a telangiectatic osteosarcoma which is rarely reported in dogs.