Original Article Body Condition and Dosage Effects on Ketamine–Xylazine Immobilization of Female White-Tailed Deer JARED F. DUQUETTE, 1 Carnivore Ecology Laboratory, Forest and Wildlife Research Center, Mississippi State University, Box 9690, Mississippi State, MS 39762, USA JERROLD L. BELANT, Carnivore Ecology Laboratory, Forest and Wildlife Research Center, Mississippi State University, Box 9690, Mississippi State, MS 39762, USA DEAN E. BEYER, Jr., Michigan Department of Natural Resources, Wildlife Division, 1990 United States Highway 41 S, Marquette, MI 49855, USA NATHAN J. SVOBODA, Carnivore Ecology Laboratory, Forest and Wildlife Research Center, Mississippi State University, Box 9690, Mississippi State, MS 39762, USA ABSTRACT Ketamine and xylazine are an effective chemical combination for white-tailed deer (Odocoileus virginianus) immobilization, but the effects of body condition on ketamine–xylazine efficacy have not been examined. We assessed the influence of ketamine dosage, xylazine dosage, body condition, age class, and injection site on successful adult female deer chemical immobilization. From January to March 2009–2011, we captured 87 deer (age 1.5 yr) in Clover traps and immobilized them using ketamine–xylazine ratios of 400 mg (n ¼ 58) or 300 mg (n ¼ 29) of ketamine to 100 mg of xylazine. Mean deer body mass was 67.8 kg (SD ¼ 12.3, range ¼ 43.0–93.0). We considered immobilization successful if deer induction was achieved 15 minutes from first ketamine–xylazine injection. Seventy-five percent of injected deer (81% with 400:100 mg ketamine:xylazine; 62% with 300:100 mg ketamine:xylazine) achieved successful induction. We recorded deer heart rate, respiration rate and rectal temperature at 0 minutes, 10 minutes, and 20 minutes post-induction. Comparison of 7 generalized linear models indicated that the probability of successful induction increased by about 6.7% with every 1.0 mg/kg increase in ketamine dosage and by about 0.7% with every 1-unit decrease in body-condition index. The remaining parameters did not influence the success of deer induction. Deer heart rate, respiration rate, and rectal temperature decreased over time post- induction, with >95% within reported ranges for ketamine–xylazine immobilization. We suggest that deer weighing 93.0 kg be injected with 5.8 mg/kg ketamine and 1.6 mg/kg xylazine to produce satisfactory induction when using similar capture methods during winter. ß 2012 The Wildlife Society. KEY WORDS body condition, capture, deer, immobilization, ketamine, Odocoileus virginianus, xylazine. Chemical immobilization is often necessary in wildlife research and management, and advancing the understanding of chemical efficacy is central to improving animal handling procedures (Beringer et al. 1996; Mitcheltree et al. 1999; DelGiudice et al. 2001, 2005; Kreeger and Arnemo 2007). Common goals of animal field capture and handling are to minimize time to induction and any adverse effects to ani- mals being studied (DelGiudice et al. 2005). Therefore, use of effective immobilization chemicals and dosages is essential to minimize animal injury or death (Conner et al. 1987, Beringer et al. 1996, DelGiudice et al. 2005, Kreeger and Arnemo 2007). Factors to consider when evaluating the safety and efficacy of immobilizing chemicals include low effective volume, short induction time, consistent immobili- zation time, and existence of an antagonist, or reversal drug (Pond and O’Gara 1996, Massolo et al. 2003). Additionally, practitioners should consider how immobilization could be affected by factors such as variation in capture method (DelGiudice et al. 2001), physiological rates (Mitcheltree et al. 1999; DelGiudice et al. 2001, 2005; Millspaugh et al. 2004), age (Kreeger and Arnemo 2007), chemical injection site (Plotka et al. 1987, Slip and Woods 1996), environmen- tal conditions (DelGiudice et al. 2001, 2005), and animal body condition (Sweitzer et al. 1997). Animal body condition is important to consider when evaluating chemical immobilization because chemicals are not absorbed at the same rate among body tissues (Slip and Woods 1996). Animals in better condition tend to metabo- lize chemicals more slowly (Sweitzer et al. 1997) and varia- tion in body fat levels (Cook et al. 2001) and body mass (Stephenson et al. 1998) can influence chemical efficacy. In addition, chemical absorption rates can differ among injec- tion sites, but are typically quicker in the shoulder than in the rump region (Kreeger and Arnemo 2007). In ungulates, body Received: 5 March 2012; Accepted: 29 August 2012 Published: 29 December 2012 1 E-mail: jduquette@cfr.msstate.edu Wildlife Society Bulletin 37(1):162–167; 2013; DOI: 10.1002/wsb.233 162 Wildlife Society Bulletin  37(1)