Evaluation of two different etorphine doses combined with azaperone in blesbok (Damaliscus pygargus phillipsi) immobilisation


Chemical immobilisation is essential for veterinarians to perform medical procedures in wild
African ungulates. Potent opioids combined with neuroleptic drugs are most often used for
this purpose. The present study aimed at comparing the quality of immobilisation and effects
on physiological variables between a high (high etorphine-azaperone [HE]: 0.09 mg kg–1) and
low etorphine dose (low etorphine-azaperone [LE]: 0.05 mg kg–1), both combined with
azaperone (0.35 mg kg–1), in 12 adult female boma-acclimatised blesbok. It was hypothesised
that a reduction in etorphine’s dose in combination with azaperone would result in less
cardiorespiratory impairment but likely worsen the quality of immobilisation. Both
treatments resulted in rapid induction and recovery times. Overall inter-treatment differences
occurred in pulse rate (HE and LE: 52 ± 15 and 44 ± 11 beats minute–1, p < 0.0001), respiratory
rate (HE and LE: 15 ± 4 and 17 ± 4 breaths minute–1, p < 0.006), partial pressure of exhaled
carbon dioxide (HE and LE: 62.0 ± 5.0 and 60.0 ± 5.6 millimetre of mercury [mmHg], p < 0.028)
and arterial carbon dioxide (HE and LE: 58.0 ± 4.5 and 55.0 ± 3.9 mmHg, p < 0.002). Both HE
and LE led to bradycardia, hypertension and marked hypoxia to a similar extent. Furthermore,
quality of induction, immobilisation and recovery were similar in both treatments. The role
of azaperone in the development of cardiorespiratory compromise and gas exchange
impairment that occurred when these combinations were used is still unclear. Further
studies are recommended to elucidate drug- and dose-specific physiological effects in
immobilised antelope.