EQUINE | Abstracts
Sedative and antinociceptive effects of different detomi-
dine constant rate infusions, with or without methadone
in standing horses
M. Gozalo‐Marcilla, A. R. de Oliveira, M. W. Fonseca, F. S. Possebon, L. Pelligand, P. M. Taylor, S. P. L. Luna
First published: 28 November 2018
Background
Standing surgery avoids the risks of general anaesthesia
in horses.
Objectives
To assess sedation, antinociception and gastrointestinal
motility in standing horses after a detomidine loading
dose and 2‐h constant rate intravenous (i.v.) infusion,
with or without methadone.
Study design
Blinded, randomised, crossover with seven healthy
adult cross‐bred horses, three geldings and four females
(404 ± 22 kg).
Methods
Sedation (<50% basal HHAG) was achieved for the
duration of the infusion, and for an additional 15 min
in DH and DHM groups. Nociceptive thresholds were
higher than baseline, to the greatest degree and the
longest duration, with DHM (ET and TT for 135 min
and MT for 150 min). After DH, TT was significantly
higher than baseline from 30 to 120 min and MT from
15 to 135 min. After DLM, ET was increased at 90 min,
TT at 30 min and MT for 120 min. Gastrointestinal
motility was reduced for up to 135 min after DL, 150
min after DLM and 210 min after DH and DHM.
Main limitations
Nociceptive thresholds are not equivalent to surgical
stimuli.
Five i.v. treatments were administered to all horses
with 1‐week washout period: saline (SAL), detomidine
low (2.5 μg/kg bwt + 6.25 μg/kg bwt/h) (DL) and high
doses (5 μg/kg bwt + 12.5 μg/kg bwt/h) (DH) alone
or combined with methadone (0.2 mg/kg bwt +
0.05 mg/kg bwt/h), (DLM) and (DHM), respectively.
Height of head above the ground (HHAG), electrical
(ET), thermal (TT) and mechanical (MT) nociceptive
thresholds and gastrointestinal motility were evaluated
at predetermined times between 5 and 240 min. A
mixed effect model and Kruskal–Wallis test were used
to analyse normally and non‐normally distributed data,
respectively.
20
Results
Conclusion
Methadone with the highest detomidine dose (DHM)
may provide sufficient sedation and analgesia for
standing surgical procedures and warrants further
investigation.
https://onlinelibrary.wiley.com/doi/full/10.1111/evj.13054
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