Physiological parameter changes during field anaesthesia of bandicoots.

Introduction: Physiological responses to anaesthesia are described for the first time in eastern barred bandicoot (EBB; Perameles gunnii) and southern brown bandicoot (SBB; Isoodon obesulus).

Method: Two hundred and six field anaesthetics were carried out on free-ranging bandicoots (82 EBB and 66 SBB) in North West Tasmania. Animals were induced and maintained under general anaesthesia using isoflurane administered via a face mask.

Results: On average, animals required 3% isoflurane for anaesthesia maintenance and recovered within 2-3 min of isoflurane being discontinued. SBB had higher respiratory rates than EBB. Otherwise, we found no significant differences in anaesthetic parameters between the bandicoot species, between sexes or for females with pouch young. Hypothermia was the only anaesthetic-associated adverse event during this study, occurring in 26 anaesthetics (12.6%). At the start of anaesthesia, bandicoots had a mean body temperature of 35.0°C (SEM 0.8, SD 1.2), and 95% of animals lost temperature during anaesthesia. Bandicoots with an initial body temperature of less than 34.5°C had 20 times greater risk (odds ratio 20.52, 95% CI 5.58-77.19) of developing hypothermia (defined as T_b < 33°C). Heart rates ranged from 100 to >300 beats per minute, and respiratory rates ranged from 8 to 64 breaths per minute. Data support a heart rate reference interval of 140-285 (mean 208, SD 42.72) and a respiratory rate interval of 10-34 for SBB (mean 21, SD 8.89) and 8-20 for EBB (mean 12, SD 4.72) during maintenance of inhalant anaesthesia.

Conclusions: With hypothermia the only anaesthesia-related adverse event during this study, results support the safety of this form of chemical restraint in the field and provide empirical data that may be used to guide anaesthesia for bandicoots. Results suggest that standard inhalational anaesthetic protocols are suitable for bandicoots irrespective of weight, sex and reproductive status.