Objective-To evaluate clinical characteristics, outcome, and prognostic variables in a cohort of dogs surviving > 1 year after an initial diagnosis ofosteosarcoma. Design-Retrospective case series. Animals-90 client-owned dogs. Procedures-Medical records for an 11-year period from 1997 through 2008 were reviewed, and patients with appendicular osteosarcoma that lived > 1 year after initial histopathologic diagnosis were studied. Variables including signalment, weight, serum alkaline phosphatase activity, tumor location, surgery, and adjuvant therapies were recorded.