Using a crossover design, the effects of the addition of
ketamine to a previously determined optimal hand-injected immobilization dosage of
carfentanil/
xylazine were evaluated in 11 adult white-tailed deer (Odocoileus virginianus). Two i.m.
ketamine dosages were evaluated: 0.15 mg/kg (low
ketamine) and 0.30 mg/kg (high
ketamine). Each deer was immobilized twice 2 wk apart. Inductions were video recorded and reviewed by observers, who had been blinded to drugs and dosages, who rated qualitative aspects. There were significant (P < 0.05) dosage-dependent decreases in heart rate, SaO2, and arterial pH, and a significant dosage-dependent increase in PaCO2. Induction times with both dosages were more rapid (mean 2.3 +/- 0.9 min for low
ketamine and 2.3 +/- 0.6 min for high
ketamine) than those reported for the same
carfentanil/
xylazine dosage used without
ketamine. Mean quality ratings, though improved compared to those reported for
carfentanil/
xylazine alone, were considered "undesirable" for both dosages.
Hyperthermia (temperature > 41 degrees C) was noted in 13 of 22 immobilizations. Arterial pH and PaO2 increased significantly from 10 to 20 min postrecumbency, but acidemia (pH < 7.3) was present throughout immobilization periods for all deer. There were
ketamine dosage-dependent increases in respiratory components of this acidemia compared with that associated with
carfentanil/
xylazine alone. Possible
hypoxemia was present at both sampling times for both groups, while hypercapnea (PaCO2 > 60 mm Hg) was present for the high-
ketamine group only. Reversal times for
naltrexone and
yohimbine were rapid (mean 2.9 +/- 0.7 min for low
ketamine and 3.3 +/- 0.8 min for high
ketamine), with no evidence of renarcotization. Although the addition of
ketamine to
carfentanil/
xylazine caused faster inductions and improved induction qualities, it also produced an increased incidence of
hyperthermia, acidemia,
hypoxemia, and hypercapnea. Supplemental
oxygen and close monitoring of body temperature is recommended when using this immobilization regimen.