Comparison of Injectable Anesthetic Combinations in Free-Ranging Two-Toed Sloths in French Guiana

Abstract

Immobilization was studied in 202 free-ranging two-toed sloths (Choloepus didactylus). All the sloths were in good condition with a body weight > 2 kg, and were anesthetized for a variety of minor clinical procedures. Intramuscular anesthetic combinations included 0.1 mg/kg acepromazine + 10 mg/kg ketamine (A/K, n = 30), 1 mg/kg xylazine + 10 mg/kg ketamine (X/K, n = 89), 10 mg/kg tiletamine/zolazepam (T/Z, n = 37), and 0.04 mg/kg medetomidine + 3 mg/kg ketamine (M/K, n = 46) antagonized by 0.2 mg/kg atipamezole. The animals were quiet during the induction stage and complete recumbency was reached in (mean +/- SD) 2.5 +/- 2.0 min with A/K, 2.7 +/- 1.7 min with X/K, 1.8 +/- 0.6 min with T/Z, and 2.5 +/- 5 with M/K. Utilization of A/K was not satisfactory because of poor anesthetic level and lack of muscle relaxation. T/Z induced immobilization was characterized by deep anesthesia and good myorelaxation, but often was associated with irregular respiration and low relative oxyhemoglobin saturation values (SpO2). Ketamine in combination with alpha2-agonists, xylazine or medetomidine, provided suitable anesthesia, with good to excellent muscular relaxation, good analgesia, high SpO2 values, moderate bradycardia, but strong bradypnea with medetomidine. Anesthesia with M/K was reversed after 41.6 min of immobilization with atipamezole. Calm recoveries were obtained and the animals were able to hang up after 10.0 +/- 7.9 min. The first signs of arousal were observed within an average of 43 to 51 min after the injection of the three other combinations. Recoveries from X/K immobilization were quiet; sloths held on after 34 min. With T/Z, recovery duration was long and very irregular at 76.7 +/- 31.3 min, some animals required 3 hr before being able to hang up. Finally, ketamine in association with an alpha2-agonist appeared to give the best chemical immobilization in wild two-toed sloths for 40 min procedures including minor surgery.

Immobilization of Free-Ranging Hoffmann's Two-Toed and Brown-Throated Three-Toed Sloths Using Ketamine and Medetomidine: A Comparasion of Physiologic Parameters

“…The mean conscious heart rate of B. variegatus in our study (76.0611 BPM) was similar to that previously reported; 79.8622.3 and 84615 BPM (Duarte et al, 1982(Duarte et al, , 2004. In another study, wild C. didactylus anesthetized with KM had an initial mean heart rate of 61615 BPM with a moderate decrease to 46613 BPM (Vogel et al, 1998). In our current study, C. hoffmanni had higher mean heart rates while anesthetized (69.269.5 BPM at 10 min to 60.268.2 BPM at 45 min) compared to mean heart rates reported previously (61617 BPM at 5 min to 47610 BPM at 45 min; Vogel et al, 1998).…”

“…No sloths developed apnea, which has been previously described in two-toed sloths using KM (Vogel et al, 1998). Respiratory rate in conscious sloths doubled with feeding (Pedrosa et al, 2002) and varied with environmental temperature, agitation, alertness, and activity (Gilmore et al, 2000).…”

“…One previously published study of injectable anesthetics in free-ranging two-toed sloths (Choloepus didactylus) recommended the use of ketamine in combination with an alpha 2 -agonist for both handling and basic clinical procedures (Vogel et al, 1998). Less is known about anesthesia and its physiologic effects in three-toed sloths (Bradypus spp.…”

“…It has been used to anesthetize a wide range of nondomestic species, especially in combination with dissociative anesthetics (Jalanka and Rö ken, 1990;Vogel et al, 1998;Sladky et al, 2000;Larsen et al, 2002;Heard et al, 2006). Adverse effects associated with medetomidine include bradycardia, hypertension, respiratory depression, and hypothermia (Jalanka and Rö ken, 1990;Kreeger et al, 1996;Vogel et al, 1998;Sladky et al, 2000;Larsen et al, 2002). Medetomidine is rapidly and completely antagonized by administration of atipamazole, a specific alpha 2 -antagonist (Jalanka and Rö ken, 1990;Kreeger et al, 1996).…”

Chelonoidis carbonaria(Testudines: Testudinidae) Activity Patterns and Burrow use in the Bolivian Chaco

“…In the study by Vogel et al, [20], rectal temperatures of anesthetized sloths in the field were highly variable, with initial temperatures ranging from 31 to 38.2 ºC.…”