Canine osteosarcoma is the most common type of dog bone cancer. It comprises 80% of all malignant bone cancer in dogs. This is an aggressive form of cancer that is highly metastatic and difficult to treat.
Canine osteosarcoma affects mainly the limbs, although it can form in any bones.
This type of bone cancer occurs mainly in older and large breed dogs, with a slight predisposition for males.
Symptoms of canine osteosarcoma
In early stages, the symptoms are not noticeable. As the tumor grows and destroys the bone, there will be lameness and swelling near a joint. The pain can cause your dog to be less active than usual. As the affected bone becomes weak, it can break and result in fracture.
Diagnosis of osteosarcoma in dogs
The first step is a physical examination of the affected area. This is followed by radiographs of the bone with tumor for characteristic changes such as bone loss, deformation or fracture. Since these findings are common in other types of canine bone cancer, it is not conclusive of osteosarcoma. A bone biopsy is necessary to provide an accurate diagnosis. If malignant osteosarcoma tumor is confirmed, radiographs of the lungs and chest area are taken to determine any metastasis.
Treatment of canine osteosarcoma
By the time your dog displays visible signs of osteosarcoma, the tumor would have likely metastasized to other organs. The treatment is twofold: managing pain and controlling metastasis.
Limb amputation gets rid of the pain. If metastasis has occurred, chemotherapy is necessary to control the spread of cancer and to maximise survival time. Dogs are capable of living with 3 legs so amputation does not restrict their activity or movement.
For some dogs with neurologic or orthopedic issues that are not suitable for amputation, there are 2 treatment options. The first option is limb sparing surgery, where the affected bone is removed and replaced with a bone graft. The other option is to manage the pain with radiotherapy and analgesic medications, without surgery.
The prognosis for canine osteosarcoma is not good when metastasis has occurred. It is worst when the tumor spread can be seen on radiographs of the chest. Your vet should be able to advise you on the best treatment options for your dog.