Abstract:
Objective To determine the cardiopulmonary and blood gas status of elephants during
chemical capture (immobilisation) with a thiafentanil-azaperone drug combination kept in
lateral recumbency.
Study design Prospective descriptive study.
Animal population Ten free-ranging adult African elephant bulls (estimated weight range
3000 to 6000 kg).
Methods Elephants were immobilised using a thiafentanil (15-18 mg) and azaperone (75-90
mg) by darting from a helicopter. Once recumbent, the tidal volume, minute volume, end-tidal
carbon dioxide, arterial blood pressure and pulse rate were recorded immediately after
instrumentation and at five-minute intervals until T20. Arterial and venous blood gases were
analysed at the time of initial instrumentation and at 20 minutes. On completion of the data
collection, the thiafentanil was antagonised using naltrexone (10 mg mg-1 thiafentanil). A
stopwatch was used to record time to recumbency (dart placement to recumbency) and time
to recovery (administering antagonist to standing). Data was checked for normality and was
found to be parametric. Data were compared using a one-way analysis of variance and
reported as mean (± SD).
Results All elephants were successfully immobilised and all physiological variables remained
constant with minimal non-significant variation over time. Average time to recumbency was
12.5 minutes. The estimated expiratory tidal volume was 21 (± 6) L breath-1 or 4.8 ± 0.8 mL
kg-1, and the measured minute volume was 103 (± 31) L minute-1. The heart and respiratory rates were 49 (±6) beats and 5 (± 1) breaths minute-1, respectively. The mean arterial blood
pressure was 153 (± 31) mmHg. The elephants were acidaemic (pH 7.18 ±0.06; bicarbonate
ion 20 ±4 mmol L-1; lactate 11 ± 4 mmol L-1), mildly hypoxemic (PaO2 68 ± 15 mmHg) and
mildly hypercapnic (PaCO2 52 ± 7 mmHg). Average time to recovery was 2.2 minutes.
Conclusion and clinical relevance African elephant bulls can be successfully immobilised
using thiafentanil-azaperone. Recumbency was rapid, the cardiopulmonary variables were
stable and within acceptable ranges, and recovery was rapid and complete. Mild hypoxaemia
and hypercapnia were evident, but does not necessarily require oxygen supplementation.
