Immobilization of Free-Ranging Hoffmann’s Two-Toed (Choloepus hoffmanni) and Brown-Throated Three-Toed (Bradypus variegatus) Sloths Using Medetomidine-Ketamine: A Comparison of Physiologic Parameters
American Association of Zoo Veterinarians Conference 2006
Christopher S. Hanley1,2, DVM; Joanna Siudak-Campfield1,2, MSc; Joanne Paul-Murphy1,2, DVM, DACZM; Christopher Vaughan3,4, PhD; Oscar Ramirez4, MSc; Kurt K. Sladky1,2, MS, DVM, DACZM

1Special Species Health Service, Department of Surgical Science, School of Veterinary Medicine, University of Wisconsin, Madison, WI, USA; 2Conservation Health Consortium, School of Veterinary Medicine, University of Wisconsin, Madison, WI, USA; 3Department of Wildlife Ecology, University of Wisconsin, Madison, WI, USA; 4International Institute for Wildlife Conservation and Management, Universidad Nacional, Heredia, Costa Rica


Recent literature has confirmed the safety and efficacy of ketamine and medetomidine (KM) combinations for immobilizing a variety of captive and free-ranging nondomestic species.1-3 Physiologic effects of KM include rapid induction/recovery, excellent muscle relaxation, peripheral vasoconstriction, initial hypertension, bradycardia, and bradypnea. While this drug combination has been evaluated in free-ranging two-toed sloths,1 there are no published data evaluating the efficacy of KM in three-toed sloths. The objectives of this study were to evaluate the safety and efficacy of KM in free-ranging two- and three-toed sloths in Costa Rica, and to compare physiologic parameters across species and gender.

Free-ranging Hoffmann’s two-toed (Choloepus hoffmanni) (n=26) and brown-throated three-toed sloths (Bradypus variegatus) (n=15) were manually captured and immobilized using ketamine (2.5 mg/kg) and medetomidine (0.02 mg/kg) administered intramuscularly. Approximately ten minutes after injection, each sloth was examined, and blood, fecal, and ectoparasite samples collected. The following physiologic parameters were monitored every five minutes for the duration of anesthesia: pulse rate, respiratory rate, body temperature, indirect systolic blood pressure, and indirect peripheral oxygenation. After 45 minutes, atipamezole (0.1 mg/kg) was administered IM to facilitate recovery. All sloths recovered uneventfully.

Physiologic parameters were compared across time, gender, and species. All sloths demonstrated a significant time-dependent decrease in pulse rate, respiratory rate, and blood pressure. Peripheral oxygenation remained similar over time for all sloths. Significant species differences were evident in respiratory rate (Choloepus >Bradypus) and blood pressure (Bradypus >Choloepus). Pulse rate showed a significant interaction between species and gender, such that Bradypus males and both Choloepus genders had greater pulse rates than Bradypus females. Gender differences were significant for body temperature (males >females), and blood pressure (males >females).

Results of this study suggest that KM is a safe and effective anesthetic combination in free-ranging two- and three-toed sloths.

Literature Cited

1.  Vogel I, de Thoisy B, Vie JC. Comparison of injectable anesthetic combinations in free-ranging two-toed sloths in French Guiana. J Wildl Dis. 1998;34:555–566.

2.  Sladky KK, Kelly BT, Loomis MR, Stoskopf MK, Horne WA. Cardiorespiratory effects of four alpha2-adrenoceptor agonist-ketamine combinations in captive red wolves. JAVMA. 2000;217:1366–1371.

3.  Chittick E, Horne W, Wolfe B, Sladky K, Loomis M. Cardiopulmonary assessment of medetomidine, ketamine, and butorphanol anesthesia in captive Thomson’s gazelles (Gazella thomsoni). J Zoo Wildl Med. 2001;32:168–175.


Speaker Information
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Christopher S. Hanley, DVM
Special Species Health Service
Department of Surgical Science
School of Veterinary Medicine
University of Wisconsin
Madison, WI, USA

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