Alfaxalone is a safe and effective anesthetic drug for the induction of general anesthesia in many nonavian companion animal species; however, its efficacy has not been fully evaluated in birds. In premedicated trials, the chickens were sedated with butorphanol 2 mg/kg intramuscularly and midazolam 0.5 mg/kg intramuscularly, 15 minutes before intravenous administration of alfaxalone. The chickens were classified as anesthetized if endotracheal intubation was achieved without eliciting a cough reflex, provoking no patient resistance, and with minimal glottis movement within 15 seconds after the administration of alfaxalone. Qualitative and quantitative data were recorded, including duration of anesthesia, quality of induction, quality of recovery, reflexes, time to sternal recumbency, time to standing, and time to normal behaviors. Survival analysis was used to analyze the association between alfaxalone dosage and premedication with time-related variables. Out of the evaluated doses, the lowest intravenous alfaxalone dose required to achieve anesthetic induction and endotracheal intubation in unpremedicated and premedicated chickens was 7.5 and 4 mg/kg, respectively. The duration of anesthesia for all dose rates within the study ranged from 51 seconds to 4 minutes 45 seconds. Premedication generally improved the quality of induction and recovery, but significantly (P < .001) increased the time required for the chickens to stand after being anesthetized and to return to normal behaviors. Most chickens exhibited varying degrees of hyperactivity on anesthetic induction and recovery. No postinduction apnea or deaths of the subject birds occurred during this investigation.
Keywords: alfaxalone; anesthesia; avian; bird; butorphanol; chicken; induction; intravenous; midazolam; premedication.