Fentanyl patch versus tramadol for the control of postoperative pain in canine ovariectomy and mastectomy.

These results indicated that the analgesic effect of the fentanyl patch was similar to that of subcutaneous (SC) tramadol in female dogs after ovariectomy, with and without unilateral mastectomy, suggesting that the fentanyl patch may represent a valid supplementary tool for the control of postoperative pain in animals after surgery.