Field System for Isoflurane Anesthesia of Multiple Species of Mesopredators

?Inhaled isoflurane is one of many chemical immobilizing agents available for field anesthesia of wildlife. We examined the use of inhaled isoflurane for field immobilization of mesopredators. Five species of mammals were anesthetized in a wetland complex in south-central Nebraska with isoflurane; we developed an induction chamber to use with a portable anesthesia machine to provide anesthesia at the capture location. Sixteen raccoons (Procyon lotor), 20 striped skunks (Mephitis mephitis), 4 Virginia opossums (Didelphis virginiana), 2 American badgers (Taxidea taxus) and 1 mink (Mustela vison) were captured and immobilized; we radio-marked 11 raccoons and 9 skunks. Induction was smooth and uneventful for all species immobilized. Mean induction times for raccoons and skunks were 10.7 min (SD = 1.1) and 11.0 min (SD = 2.4) respectively. Mean handling times (post induction) were 7.1 min (SD = 3.9) for raccoons and 7.3 min (SD = 4.8) for skunks. All animals, with the exception of opossums, were fully recovered within 15 min (raccoon mean recovery: 11.1 min, SD = 3.5; skunk mean recovery: 10.9 min, SD = 3.7). Recovery times for radio-collared animals and uncollared animals did not differ, and individuals with longer handling times did not require longer recovery times. Although isoflurane requires more equipment than injectable anesthesia methods, its short recovery time and wide safety margins deem it practical for use in a variety of field applications.