Alfaxalone anesthesia by immersion in oriental fire-bellied toads (Bombina orientalis)

Abstract

ObjectivesTo establish an effective alfaxalone concentration to be used for bath immersion of fire-bellied toads (Bombina orientalis) and to describe its effects. Study designProspective experimental study. AnimalsThirteen oriental fire-bellied toads. MethodsThe study was carried out in two phases. The pilot phase involved five animals and aimed to identify an alfaxalone concentration capable of producing induction of anesthesia, defined as immobility with a head down position and loss of responsiveness to stimulation with a stick. The following trial in an additional eight toads used the effective alfaxalone concentration established during the pilot phase. Data from 11 animals (three toads in the pilot study and the eight additional toads) were analyzed. Twenty minutes after immersion in the anesthetic solution, the toads were removed from the bath, and heart rate, respiratory rate, the righting, myotactic and the nociceptive withdrawal reflexes were evaluated every 5 minutes. The loss of both righting and nociceptive withdrawal reflexes was considered indicative of a surgical depth of anesthesia. The time elapsed from anesthetic induction to return of righting reflex, the quality of recovery and the occurrence of undesired effects were observed and recorded. ResultsImmersion was found to be a suitable anesthetic technique for oriental fire-bellied toads and 200 mg L−1 alfaxalone concentration produced anesthetic induction in 10 out of 11 toads. Side effects, such as skin irritation, erythema and changes in cutaneous pigmentation, were not observed in any animal. The duration of anesthesia ranged from 10 to 30 minutes after removal of the toads from the alfaxalone bath, and surgical depth of anesthesia was never achieved. Conclusions and clinical relevanceIt was concluded that alfaxalone anesthesia induced by immersion in a concentration of 200 mg L−1 is only suitable for toads undergoing non-invasive short procedures.