Fully Reversible Anesthesia in Asian Small-Clawed Otters (Aonyx cinereus) Using Dexmedetomidine-Midazolam-Butorphanol, and Comparison of Anesthetic and Cardiac Parameters with Ketamine-Midazolam
American Association of Zoo Veterinarians Conference 2011

Christine V. Fiorello1, DVM, PhD, DACZM; Sam Rivera2, DVM, DABVP (Avian); Tonya Clauss3, DVM, MS; Benjamin Brainard4, VMD, DACVA, DACVECC; Gregg Rapoport4, DVM, DACVIM (Cardiology); Hayley Murphy2, DVM; Aimee Berliner3, DVM

1Oiled Wildlife Care Network, Wildlife Health Center, School of Veterinary Medicine, University of California, Davis, CA, USA; 2Zoo Atlanta, Atlanta, GA, USA; 3Georgia Aquarium, Atlanta, GA, USA; 4Department of Small Animal Medicine, University of Georgia, Athens, GA, USA


The ability to fully reverse anesthesia has benefits for animals both in captivity and in the field. Recently a medetomidine-butorphanol-midazolam combination, reversed with atipamezole-naloxone (or naltrexone)-flumazenil has been used with success in felid and canid species.1,2 We anesthetized twelve captive Asian small-clawed otters during their annual exams, substituting the newly available alpha-2 agonist dexmedetomidine for medetomidine. We measured temperature, heart rate (HR), respiratory rate, oxygen saturation, end-tidal CO2, blood pressure, arterial blood gas values, and echocardiographic parameters and compared them with captive otters anesthetized with ketamine-midazolam (KM). We used a crossover study design. For the new protocol (DBM), we administered dexmedetomidine 0.015 mg/kg; butorphanol 0.2 mg/kg; and midazolam 0.15 mg/kg intramuscularly for immobilization and atipamezole 0.19 mg/kg; naloxone 0.1 mg/kg; and flumazenil 0.06 mg total dose intramuscularly for reversal. For the KM protocol, we used ketamine 10.1 mg/kg and midazolam 0.27 mg/kg intramuscularly. All otters were intubated, and isoflurane was administered if necessary. Otters were monitored every 5 minutes throughout the procedure. We have found that average HR and lactate were higher with KM (98 vs. 146 bpm; 0.37 vs. 0.46 mmol/L), whereas average mean blood pressure was higher (94.7 vs. 65.6 mm Hg) and the average decrease in temperature was greater (5.3 vs. 4.1°F) with DBM. Induction and recovery were shorter and subjectively smoother with DBM.


The authors thank the veterinary technicians, house officers, husbandry staff, and aquarists for their help with this work, and B. McCrary and Choice Medical Systems for the generous loan of the ultrasound probe.

Literature Cited

1.  Larsen RS, Loomis MR, Kelly BT, Sladky KK, Stoskopf MK, Horne WA. Cardiorespiratory effects of medetomidine-butorphanol, medetomidine-butorphanol-diazepam, and medetomidine-butorphanol-ketamine in captive red wolves (Canis rufus). J Zoo Wildl Med. 2002;33:101–107.

2.  Wenger S, Buss P, Joubert J, Steenamp J, Shikwambana P, Hatt J-M. Evaluation of butorphanol, medetomidine, and midazolam as a reversible narcotic combination in free-ranging African lions. Vet Anaesth Analg. 2010;37(6):491–500.


Speaker Information
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Christine V. Fiorello, DVM, PhD, DACZM
Oiled Wildlife Care Network
Wildlife Health Center
School of Veterinary Medicine
University of California
Davis, CA, USA

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