Evaluation of the effects of intramuscular injection volume on midazolam-butorphanol induced sedation in domestic pigeons (Columba livia)

Abstract

BackgroundCombinations of midazolam and butorphanol are commonly used in avian sedation protocols but no studies have been performed in Columbiformes. Minimizing intramuscular drug injection volumes is desirable, in order to reduce the potential for injection-induced discomfort. Reduction of drug injection volumes can be achieved by using higher concentrated drug formulations. The goals of this study were to evaluate a midazolam-butorphanol sedation protocol in domestic pigeons and to evaluate if a difference in total drug injection volume has an effect on sedation parameters in this species. MethodsTwelve adult pigeons were sedated with butorphanol (2 mg/kg) combined with 4 mg/kg of midazolam as either a standard (5 mg/mL) or concentrated (50 mg/mL) formulation, intramuscularly, in a randomized, blinded, complete cross-over study. Various parameters were used to assess for differences in sedation onset, depth, and recovery. Flumazenil (0.05 mg/kg) was administered intramuscularly for reversal of midazolam 30 minutes after sedative administration. ResultsThe sedation protocol resulted in moderate sedation and all birds became sternally recumbent, while 4of 12 birds lost righting reflex. Recovery was rapid in all birds following administration of flumazenil and no adverse reactions were observed. Significant differences in drug injection volumes had no clinically relevant effects on sedation parameters. Conclusions and clinical relevanceUse of concentrated midazolam resulted in ∼3.5 times smaller total injection volumes, while achieving the same efficacy as standard concentration of midazolam. The reduced injection volumes are desirable from an animal welfare standpoint, as they may reduce the risk of local discomfort associated with intramuscular injections.