Canine Osteosarcoma

Canine Osteosarcoma

Osteosarcoma (OSA) is the most common primary bone tumor in dogs. Its most common form affects the appendicular skeleton of large or giant breed dogs; however, it can also affect the axial skeleton as well, which occurs more frequently in smaller dogs. In dogs, it is a locally and metastatically aggressive disease that is very similar to the disease’s human form. This PowerPage will focus on the more common appendicular form with a brief review of the axial skeleton form of the disease.

Key Points         

  • Most commonly occurs in large and giant breed dogs in the metaphyseal regions of the appendicular skeleton
    • Distal radius, proximal humerus, distal femur, proximal tibia (“away from the elbows and toward the knees”)
  • Can present for chronic progressive lameness or acute lameness after an inciting incident such as jumping off the couch or out of the car
  • Amputation of an affected limb is the most effective way to eliminate pain but is considered palliative as 90% of dogs will eventually develop metastasis
  • Metastasis most commonly spreads to the lungs but can occasionally occur in lymph nodes or other bones
  • Chemotherapy can help extend median survivals to 10-12 months


Limb radiographs

  • Classically a lytic and productive lesion at the metaphysis of the bone
  • A diaphyseal lesion should raise red flags for the lesion potentially being metastatic from a primary tumor from somewhere else in the body
  • Do not cross joints into adjacent bones

Figure 1. Lateral radiograph of a productive and lytic osteosarcoma lesion of the distal radius.

Image courtesy of DVM Insight.

Fine needle aspirate cytology

  • Aspirate the center of the lesion
    • Aspirates of the periphery often result in “reactive bone”
  • Use ultrasound guidance to help insert the needle into cracks of the cortex
  • Warn the owner about the possibility of pathologic fracture with aspiration or biopsy


  • May be required for a definitive diagnosis in equivocal cases

Thoracic radiographs

  • Pulmonary metastasis visible in less than 10% of cases at the time of diagnosis but will develop in the future in most cases
    • Visible pulmonary metastasis portends a poor prognosis and therefore must be performed prior to treatment

Bone scan or nuclear scintigraphy

  • Used to find or rule out suspected bone metastasis
  • Technetium-99–hydroxymethylene diphosphonate binds to areas of active bone and is detected in imaging
  • Sensitive, but poorly specific
    • Increased uptake can occur with bone tumors, arthritis, fractures, or osteomyelitis
  • Alternatively, full body radiographs can be performed


  • Elevation in alkaline phosphatase on a chemistry panel is associated with a worse prognosis



  • Amputation is the most effective way to alleviate pain of bone destruction
    • Palliative as most dogs will develop metastasis in the future
  • Limb-sparing procedures
    • Surgical removal of the bone tumor with replacement of a prosthetic at the ostectomy site
    • Also considered palliative
    • High rates of complications: chronic resistant infections, tumor recurrence, failure of surgical constructs
    • Expensive and limited to experienced surgeons

Radiation therapy

  • Can be effective in palliating the pain of bone tumors in up to 75% of cases, for about 2-3 months
    • No detectable improvement in pain in 25%
  • Pathologic fractures may be more likely to occur if pain is well controlled and use of the limb is increased


  • Proven to extend survivals over surgery alone
  • Chemotherapy protocols mostly consist of a platinum drug (cisplatin or carboplatin) as a single agent or in conjunction with Adriamycin (doxorubicin)
  • Generally thought not to be effective if macroscopic disease is present
  • Bisphosphonates (pamidronate) are osteoclast inhibitors that can help palliate pain in patients where surgery is not an option


Median survival times

  • Amputation alone: 4-6 months
  • Surgery (amputation or limb spare) with chemotherapy: 10-12 months
  • Presence of macroscopic metastatic disease: 1-3 months

Axial osteosarcoma       

  • Make up 25% of all OSAs and occur more commonly in small- or medium-sized dogs compared to appendicular OSA
  • Common locations: mandible, maxilla, scapula, ribs, spine, pelvis
  • The mandible has a better prognosis compared to all other sites
    • 70% 1-year survival with surgery alone
  • Other locations generally thought to have aggressive clinical courses similar to the appendicular disease
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