• elasmobranch;
  • pain;
  • analgesia;
  • shark;
  • nociception


The mediation of nociception with analgesic medications has not been well documented in elasmobranchs. The purpose of this study was to determine effective analgesic doses of the opioid agonist-antagonist, butorphanol, and the non-steroidal anti-inflammatory drug, ketoprofen, in an elasmobranch. This was evaluated by repetitively assessing minimum anesthetic concentrations of the immersion anesthetic, tricaine methanesulfonate (MS-222), required to prevent response to noxious stimuli in chain dogfish (Scyliorhinus retifer) when administered multiple doses of each of the analgesics (0.25, 0.5, 1.0, 2.5, and 5.0 mg/kg butorphanol and 1.0, 1.5, 2.0, and 4.0 mg/kg ketoprofen). Baseline concentrations of MS-222 required to prevent a response to a noxious stimulus were determined for each animal and served as the controls. Although individual animals displayed a reduction in MS-222 concentration with various doses of both analgesics, no statistically significant difference was noted between control animals and animals given analgesics. It is plausible that unique elasmobranch anatomy, lack of appropriate medication dose or timing of administration, and other physiological factors not yet identified may have contributed to the lack of apparent efficacy of the analgesics evaluated in this study. Zoo Biol 0:1–10, 2006. © 2006 Wiley-Liss, Inc.