Soft tissue sarcoma (STS) encompasses a number of neoplasms that are derived from mesenchymal cells including fibrosarcoma, myxosarcoma, hemangiopericytoma, and undifferentiated sarcoma. In the dog, STSs arise frequently in the dermis/subcutis and represent up to 15% of the neoplasms in this location. Currently, canine STSs are graded histologically based on the presence and degree of necrosis, atypia, and mitotic figures which is used to determine the likelihood of recurrence and the possibility of adjunctive treatment. Histologic grading schemes inherently have several limitations and recent data in human STS strongly support the notion that intratumoral genetic differences are better predictors of biological behavior, including metastatic potential, recurrence, and prognosis, when compared to histologic grade. Our understanding of the pathogenesis and patient outcome of canine STS is limited by an unknown genomic profile of these neoplasms. Utilizing RNA recovered from formalin-fixed, paraffin embedded (FFPE) and fresh frozen (FF) canine STS, we will develop a transcriptional profile of canine STS that will be used to better optimize and refine diagnosis including tumor classification, prognosis, and predict response to post-surgical intervention.