Abstract Introduction: Opiranserin, a non-opioid analgesic acting as a glycine transporter 2 inhibitor and 5-HT2A receptor antagonist, was evaluated for reducing intraoperative rescue analgesia and postoperative pain in dogs undergoing castration under isoflurane anesthesia. Materials and methods: Eight healthy male Beagle dogs were randomized to receive a continuous rate infusion of opiranserin (5 mg·kg−1·h−1 for 1 h before induction, then 0.33 mg·kg−1·h−1 for 9 h; n = 4) or 0.9% saline (n = 4).
