Abstract
The antitumor activity of piroxicam and cyclooxygenase （COX）-2 expression was investigated in dogs with primary renal tumor. By immunohistochemistry, COX-2 was expressed in 42.9% （6/14） of the tumors examined. All of the tumors with positive COX-2 staining were epithelial in origin （renal adenocarcinoma and transitional cell carcinoma）, and COX-2 expression was also confirmed in metastatic tumors. COX-2 was not expressed in mesenchymal and embryonic tumors. Among dogs that were not surgically treated, those treated with piroxicam （3/8） had a significantly longer median survival than those untreated （5/8）. Among dogs that had metastasis at the time of first presentation, the median survival was significantly longer in dogs treated with piroxicam （8/16） than those without （8/16）. Tumor shrinkage at both primary and metastatic sites was confirmed in one dog treated with piroxicam alone. These results suggest possible antitumor activities of piroxicam in canine primary renal tumors.
