EQUINE | Abstracts
A comparison of two ketamine doses for field anaesthesia
in horses undergoing castration
H. Harðardóttir, P. J. Murison, K. Blissitt, S. Olason, R. E. Clutton
First published: 24 November 2018
Background
Ketamine at 2.2 mg/kg given i.v. is often used to
induce anaesthesia for surgical procedures in horses
under field conditions. Commonly, additional doses
are needed to complete the surgery. We hypothesised
that surgical conditions would be improved when 5
mg/kg of ketamine was used to induce anaesthesia,
while induction and recovery qualities would not
differ from those when 2.2 mg/kg ketamine was used.
Objective
To compare the anaesthetic effects of two ketamine
doses (5 and 2.2 mg/kg) during field anaesthesia for
castration of horses.
Study design
Prospective, randomised, blinded, clinical study.
Method
Seventy‐seven client‐owned Icelandic horses presented
for castration under field conditions were studied.
Pre‐anaesthetic medication was xylazine (0.7 mg/kg)
butorphanol (25 μg/kg) and acepromazine (50 μg/kg)
injected i.v. Anaesthesia was induced with either 2.2
mg/kg (K2.2) or 5 mg/kg (K5) i.v. of ketamine mixed
with diazepam (30 μg/kg). The quality of induction,
surgical conditions and recovery were compared
using subjective and objective measures, and the
number of additional ketamine doses recorded.
18
Results
Ketamine 5 mg/kg provided better surgical conditions
and a more rapid induction. Recovery quality was
subjectively better in K2.2. Five horses in K2.2 and
two in K5 required additional ketamine doses.
Main limitations
While the pre‐anaesthetic sedation and benzodiazepine
doses were consistent among horses, the level of
sedation and muscle relaxation achieved differed.
Conclusion
A ketamine dose of 5 mg/kg can be used to improve the
quality of field anaesthesia for castration in Icelandic
horses. Although recovery quality is subjectively
better when using 2.2 mg/kg, no adverse events were
observed during recovery with either dose
https://onlinelibrary.wiley.com/doi/pdf/10.1111/evj.13052
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