Determination and Evaluation of an Optimal Dosage of Carfentanil and Xylazine for the Immobilization of White-Tailed Deer (Odocoileus Virginianus)

Abstract

Using an iteration method, optimal hand-injected immobilization dosages of carfentanil/xylazine (CAR/XYL) were determined for 13 adult white-tailed deer (Odocoileus virginianus). Deer were temporarily restrained in a squeeze chute and were repeatedly immobilized one to four times at 2-5-wk intervals from December 2002 to March 2003. A fixed ratio of 1 mg CAR:10 mg XYL intramuscularly was used, increasing or decreasing the dosage until the optimal dosage (defined by an induction time < 3 min and PaCO(2)< 60 mmHg) was reached for each animal. Inductions were video-recorded and reviewed by observers blinded to drugs and dosages, who rated qualitative aspects of each induction. There were significant (P < 0.05) dosage-dependent decreases in induction time, time to first effect, PaO(2), SaO(2), and arterial pH, and significant dosage-dependent increases in PaCO(2) and quality ratings. The median optimal dosage (mOD) was 0.03 (range, 0.015-0.06) mg/kg CAR+0.3 (range, 0.15-0.6) mg/kg XYL. Induction times using the mOD were rapid (median 3.0 min [range, 1.8-10.0]), but quality ratings were considered undesirable for nine of 13 deer. Increased rectal body temperatures of 40.6+/-0.5 C (mean +/- SD) were noted in all deer and hyperthermia (T > 41 C) was noted in three. There was a positive correlation between body temperature and induction time (r=0.44). Heart rates significantly decreased from 5 to 15 min postinduction and remained decreased at the 20-min reading; there was occasional bradycardia. There was a significant increase in pH from 10 to 20 min postinduction, but metabolic acidemia (pH<7.3) persisted throughout the immobilization periods for all deer. Possible hypoxemia (SaO(2) and SpO(2)<90 mmHg but PaO(2)>60 mmHg) was present after induction, while hypercapnea (PaCO(2) > 60 mmHg) did not occur. Reversal times with naltrexone and yohimbine were rapid (mean 3.7+/-1.5 min) and uneventful, with no evidence of renarcotization. Although the median optimal dosage produced rapid inductions, no respiratory depression, complete reversal after antagonist administration, and no renarcotization, negative attributes included elevated body temperatures, acidemia, and undesirable induction qualities.

Physiological evaluation of free-ranging moose (Alces alces) immobilized with etorphine-xylazine-acepromazine in Northern Sweden

“…Hypoxemia was also found in cases where alpha-2 combinations were used in combination with opioids [28,30]. The hypoxemia seen in this study as in studies of other ruminants, indicates that oxygen supplementation is indicated in these species.…”

“…Moderate to severe hypoxemia has also been documented in other ruminants anesthetized with alpha-2 combinations including wood bison (Bison bison) [27], mule deer ( Odocoileus heminus ) [28,29], wapiti ( Cervus canadensis ) [29,30] and white tailed-deer ( Odocoileus virginianus ) [31]. Hypoxemia was also found in cases where alpha-2 combinations were used in combination with opioids [28,30].…”

“…Hypercapnia has been documented during anesthesia in a number of ruminants including wood bison [27], mule deer [28,29] and wapiti [29,30]. In a study comparing oxygen and medical air supplementation in wapiti, both groups had increasing PaCO 2 over time, but this was significantly higher in the group receiving oxygen [32].…”

Chemical Immobilization of Raccoons (Procyon Lotor) With Ketamine-Medetomidine Mixture and Reversal With Atipamezole

“…While there is no obvious reason to expect that drug effect would be different for captive versus wild animals of the same species, it is possible that the effect of repeated immobilization on the efficacy of anesthesia may be undetectable in the wild, given that the number of repeated immobilizations for wild animals is typically lower than for captive animals. Although some previous studies have found no effect of repeated immobilization on wild animals (Poole et al, 1993;Thil and Groscolas, 2002;Storms et al, 2005), others have suggested that animals can become habituated to drugs (Field et al, 2002;Wheatley et al, 2006). However, it is unknown whether an increase in drug tolerance due to repeated use of anesthesia is applicable to a wide range of species.…”

Immobilization of white‐tailed deer with telazol, ketamine, and xylazine, and evaluation of antagonists

“…During our study, the temperature of 3 animals immobilized with TKX exceeded 41° C. High initial temperature likely was a result of physical exertion that occurred when darted males were pursued by other males in our facility. One male in our study was gored by another and had an initial rectal temperature of 42° C. Despite those instances, initial rectal temperatures (38.9° C) and those immediately prior to antagonist administration (38.6° C), were comparable to or less than mean values reported for other drug combinations with white‐tailed deer (range: 39.2–42.1° C; Miller et al 2003, 2009; Storms et al 2005, 2006; Muller et al 2007).…”