Osteosarcoma (OS) is the most common primary neoplasm of the appendicular skeleton in dogs and occurs about 3 to 4 times more often than axial skeleton OS tumors. Appendicular OS is generally a rapidly progressive tumor with early metastases to the lungs and early mortality. Medium and large dog breeds are predisposed, and there are strong site predilections in the appendicular skeleton. Tumors occur more often in the forelimbs and usually involve the metaphyses of the distal radius or proximal humerus. In the hind limb, the distal femur and proximal tibia are most common. The gross and radiographic appearances of the OS bone lesions are quite variable and may appear similar to a mycotic bone infection. Direct sampling of the tissue is needed for a definitive diagnosis, although age, breed, site of lesion, anatomic location, and other clinical information may suggest neoplasia over mycotic infection or vice versa. Pathologic fractures are a risk due to loss of integrity of normal bone structure. Treatment options range from palliative pain management to limb amputation and chemotherapy. Prognosis is guarded in all cases due primarily to rapid progression and early micro-metastases.
Links to sections in MVM:
Osteomyelitis in Small Animals
Bone Tumors in Small Animals
References
J Vet Intern Med. 2015 Nov-Dec;29(6):1584-94. doi: 10.1111/jvim.13635. Epub 2015 Oct 1. Neumann ZL, Pondenis HC, Masyr A, Byrum ML, Wycislo KL, Fan TM. The Association of Endothelin-1 Signaling with Bone Alkaline Phosphatase Expression and Protumorigenic Activities in Canine Osteosarcoma. J Vet Intern Med. 2015 Nov-Dec;29(6):1584-94. doi: 10.1111/jvim.13635
Sabattini S, Renzi A, Buracco P, Defourny S, Garnier-Moiroux M, Capitani O, Bettini G. Comparative Assessment of the Accuracy of Cytological and Histologic Biopsies in the Diagnosis of Canine Bone Lesions. J Vet Intern Med. 2017 May;31(3):864-871. doi: 10.1111/jvim.14696