Investigation of Injectable Anesthetic Agents in Mallard Ducks (Anas platyrhynchos): A Descriptive Study

Abstract

Injectable anesthetic regimens produce variable results in waterfowl and are not cur- rently used for invasive surgical procedures. This study was undertaken to identify an injectable anesthetic protocol that could produce anesthesia and analgesia for an invasive surgical procedure, with rapid recovery, in mallard ducks. Reversible anesthesia is desirable when working with free- ranging waterfowl to reduce stress, prevent pair bond disruption, and reduce detrimental effects of egg cooling when females are not incubating. Thirty healthy adult mallard ducks were used in the study. The injectable drugs investigated included xylazine, medetomidine, ketamine, midazolam, butorphanol, fentanyl, sufentanil, methohexital, alphaxalone-alphadolone, and propofol. Reversal agents atipamezole and flumazenil were also examined. Drugs were administered alone or in com- bination by the intramuscular, intranasal, or intravenous route. Anesthetic effects were recorded, and analgesia was assessed by response to toe pinching and feather plucking. Incremental doses were given when the effect of the initial dose was poor. No anesthetic regimen was effective when administered by the intramuscular route, and intranasal administration resulted in unreliable anes- thetic depth. Intravenous administration of anesthetic agents was more effective; however, few regimens provided adequate duration of anesthesia or analgesia for a surgical procedure. Intravenous administration of a medetomidine-midazolam-ketamine combination produced adequate anesthesia and analgesia of 30-minute duration, and the effects of the combination could be reversed with atipamezole and flumazenil. Administration of propofol intravenously produced smooth induction and recovery, excellent muscle relaxation, and short duration of anesthesia requiring additional boluses to prolong and maintain anesthesia.