Abstract

Our objective was to compare the effects of immobilization of wild deer (Odocoileus virginianus) with butorphanol-medetomidine via either hand-injection in Clover traps or remote injection by dart. Trapped (n=6; weighing 55 [31, 58] kg, median [minimum, maximum]) and darted (n=16; 56 [28, 65] kg) female deer were injected with 0.64 [0.43, 0.75] mg/kg butorphanol (Wildlife Pharmaceuticals, Inc., Fort Collins, CO) plus 260 [170, 300] µg/kg medetomidine (Wildlife Pharmaceuticals, Inc.) for tubal ligation. Differences between groups were tested using the Wilcoxon rank-sum test, and a Bonferroni correction was made to account for multiple comparisons. Most deer in both groups had PaO₂ values less than 80 mm Hg, but darted deer were significantly more hypoxemic. Standard base excess and pH were lower in trapped deer than darted deer, and the trapped deer had a metabolic acidemia. Median plasma lactate was more than five-fold higher and median serum creatine kinase was more than seven-fold higher in trapped deer. Plasma cardiac troponin was undetectable in 11 out of the 14 darted deer tested; it was significantly higher in the trapped deer. Median body temperature in trapped deer was 1.4°C higher than in darted deer. These data suggest that deer anesthetized by hand-injection in Clover traps are more physiologically stressed than deer remotely injected by dart, to the extent that myocardial damage is produced. The hypoxemia seen in both groups is likely due to medetomidine administration.