Retrospective Evaluation of Whole Body Computed Tomography for Tumor Staging in Dogs with Primary Appendicular Osteosarcoma.

Objective: To evaluate whole body computed tomography (CT) for staging canine appendicular osteosarcoma.

Study Design: Retrospective case series.

Animals: Client-owned dogs diagnosed with appendicular osteosarcoma (n=39).

Methods: Medical records for client-owned dogs diagnosed with appendicular osteosarcoma from August 2008 to July 2014 were reviewed. Dogs were included if they had a confirmed diagnosis of appendicular osteosarcoma and were staged using whole body CT. Data collected included signalment, body weight, primary tumor location, serum alkaline phosphatase (ALP) activity, findings on 3-view thoracic radiographs, cytologic or histologic results, and findings on CT.

Results: Thirty-nine dogs (median age 8.5 years; median body weight 37 kg) had osteosarcoma of the distal radius (n=17), proximal humerus (11) and other sites. Serum ALP activity was elevated in 14 dogs. Bone metastasis was not detected in any dog on whole body CT. Pulmonary metastasis was considered definitive on CT based on board certified radiologist assessment in 2/39 dogs (5%). Two additional dogs (2/39, 5%) had soft tissue masses diagnosed on CT, consistent with concurrent, non-metastatic malignancies.

Conclusion: Bone metastases were not identified in any dog with whole body CT. Thoracic and abdominal CT detected lung lesions and concurrent neoplasia in dogs with primary appendicular osteosarcoma. Whole body CT may be a useful adjunct to other screening tests for disseminated malignancy.