Lanebern Saint Bernards
The most common type of bone tumor seen in dogs is osteosarcoma. Typical clinical signs include a progressive lameness (limp) in an older, large breed dog in association with a swelling or pain in a long bone. Certain breeds appear to have a genetic predisposition for development of osteosarcoma , including the Irish wolfhound, Rottweiler, and retriever breeds. The radiographic appearance of mixed bone destruction and excessive bone production in a succeptible breed is highly suggestive of this diagnosis, but suspicious areas can be confirmed by a needle biopsy performed under a brief anesthetic. Chest x-rays or computerized tomography (CT s
can) are required to assess for metastasis (spread of the tumor) to the lungs. Bone cancer is typically malignant and is rarely cured by surgical therapy. Thus, therapy is directed at two goals: 1) pain relief by surgical removal of the bone tumor and 2) slowing the spread of the tumor by administering chemotherapy. The most common palliative surgery performed in dogs with bone cancer affecting one of the leg bones is amputation of the affected limb. Although many pet owners are hesitant to perform amputation surgery on their dogs, postoperative surveys show that 80-90% of people are happy that they made the decision and would do so again, if required in future pets. For dogs with concurrent orthopedic or neurologic problems that would make them poor candidates for amputation surgery, various limb sparing te
chniques are available, which involve local removal of the affected bone and replacement with various metallic or bone implants. Radiation therapy may also be used to control pain and local tumor growth. Survival statistics for dogs with osteosarcoma is well described and averages approximately 5 months without chemotherapy and 12 months with chemotherapy. Dogs will typically develop evidence of heavy breathing or coughing as metastasis of tumors occurs in the lungs. Dogs that do not receive pain relieving surgery can be treated with various analgesic drugs, but these drugs have limited efficacy and owners will often decide that quality of life is not acceptable after several weeks. Weakening of the bone in the location of the tumor may also predispose to pathologic fracture, causing sudden increase in discomfort and difficulties with medical management.