Investigation into the characteristics, triggers and mechanism of apnoea and bradycardia in the anaesthetized platypus (Ornithorhynchus anatinus)

By relating respiratory and heart rate changes observed in some platypuses under isoflurane anaesthesia to those produced by various stimuli to the trigeminal nerve we propose that in platypuses the changes that can result from isoflurane gas in the nasal cavity are most appropriately described by the term ‘nasopharyngeal response’.AbstractHealth and conservation research on platypuses (Ornithorhynchus anatinus) may require anaesthesia to reduce stress and the risk of injury to both the animal and the researcher, as well as to facilitate examination and sample collection. Platypus anaesthesia can be difficult to manage, with reports of periods of apnoea and bradycardia described. This study investigated the conditions around sudden-onset apnoea and bradycardia in 163 field-anaesthetized platypuses as part of a health study. Anaesthesia was induced and maintained using isoflurane delivered in oxygen by face mask. Sudden-onset apnoea and bradycardia was observed in 19% of platypuses, occurring either at induction of anaesthesia, during recovery, or both. At induction, occurrence was more often recorded for adults (P = 0.19) and was correlated with low body temperature (P