Ovariohysterectomy is an important surgery in veterinary medicine and is associated with significant pain and/or fatigue. Butorphanol is a commonly used k-agonist/µ-antagonist opioid that provides only mild analgesic effects of short duration. Firocoxib, a nonsteroidal antiinflammatory drug (NSAID), is a highly selective cyclooxygenase-2 (COX-2) inhibitor. In general, coxibs are more lipophilic than many nonselective NSAIDs and can readily cross the blood–brain barrier, a property that may allow them greater systemic distribution and may facilitate inhibition of the central regulation of COX-2. In the present study, 25 dogs underwent routine ovariohysterectomy after receiving either butorphanol (n = 12) or firocoxib (n = 13) as part of their preanesthetic protocol. All dogs were sedated with acepromazine, induced with propofol, and maintained under general anesthesia with isoflurane. Eleven dogs (91.7%) in the butorphanol group required postoperative rescue analgesia as compared with only 2 dogs (15.4%) in the firocoxib group.
In addition, the firocoxib group had significantly lower pain scores. Sedation scores were not significantly different between groups; however, dogs receiving butorphanol did not require as much propofol during induction.

Commentary: This study supports previous data showing that butorphanol is a poor analgesic in dogs but may be useful for sedation. Previous data have also proven that the sedation effects of butorphanol should not be confused with true analgesia. Firocoxib proved to be a good preoperative analgesic and is well tolerated. Further studies are needed to compare all of the common NSAIDs that are used perioperatively, including their availability, cost, and the practicalities of dispensing the medication when patients go home. The importance of multimodal analgesia and anesthesia cannot be overemphasized.—Heather Troyer, DVM, Diplomate ABVP

Postoperative analgesic effects of butorphanol or firocoxib administered to dogs undergoing elective ovariohysterectomy. Camargo JB, Steagall PVM, Minto BW, et al. VET ANAESTH ANALG 38:252-259, 2011.