Abstract
Objective
To characterize and compare two intramuscular drug protocols using alfaxalone and
alfaxalone–medetomidine combination for the field immobilization of free-ranging koalas.
Study design
Blinded, randomized, comparative field study.
Animals
A total of 66 free-ranging koalas from the Mount Lofty Ranges, South Australia.
Methods
Koalas were randomly allocated into two groups. Group A animals were given alfaxalone
alone at 3.5 mg kg–1. Group AM animals were given alfaxalone 2 mg kg–1 and medetomidine 40 μg kg–1, reversed with atipamezole at 0.16 mg kg–1. Blinded operators recorded heart rate (HR), respiratory rate (fR), cloacal temperature, depth of sedation and times to: first effect, sedation suitable
for clinical interventions, first arousal and full recovery. Data were analysed using
independent t test, Mann–Whitney U test, chi-square analysis and log-rank test at 5% level of significance.
Results
Suitable immobilization for clinical examination and sample collection was achieved
in all animals. In groups A and AM, median time to working depth was 6.5 minutes (range:
3.4–15) and 8.1 minutes (range: 4.3–24) and time to complete recovery was 66 minutes
(range: 12–138) and 34 minutes (range: 4–84), respectively, following reversal. Time
to first effect was significantly shorter in group A (p = 0.013), whereas time to full arousal was significantly shorter in group AM (p = 0.007) probably due to the administration of atipamezole. Maximum HR was 117 ±
28 beats minute–1 in group A, which was a significant increase from baseline values (p < 0.0001), whereas group AM showed a significant tachypnoea of 67 ± 25 (normal fR 10–15; p < 0.0001).
Conclusions and clinical relevance
Both the protocols produced immobilization, enabling clinical examination and sample
collection; however, protocol AM was more suitable for field work due to shorter recovery
times.
Keywords
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Article info
Publication history
Published online: February 27, 2020
Accepted:
October 8,
2019
Received:
June 7,
2019
Identification
Copyright
© 2020 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.
