This study aims to investigate FAP and EDB+FN expressions in canine tumors and assess their potential as druggable targets in animal patients.<h4>Methods</h4>FAP and EDB+FN expression was assessed by immunohistochemistry on 88 canine tumors, including Soft Tissue Sarcomas [STS], Osteosarcomas [OSA], Hemangiosarcomas [HSA], Apocrine Gland Anal Sac Adenocarcinomas [AGASAC], Mast Cell Tumors [MCT], Lymphomas, and Melanomas, using polyclonal and monoclonal anti-FAP and the L19 anti-EDB antibodies. The gene discussed is FN1; the disease is mast cell neoplasm.