Abstract
Objective
To study the sedative and cardiorespiratory effects of transnasal (TN) administration
of a combination of dexmedetomidine (DEX), midazolam (MID) and butorphanol (BUT) administered
through a nasal catheter to rabbits undergoing diagnostic procedures.
Study design
Descriptive cross-sectional experimental study.
Animals
Eight healthy New Zealand White rabbit does (12 ± 1 months old, 3.5 ± 0.3 kg).
Methods
DEX (0.1 mg kg−1), MID (2 mg kg−1) and BUT (0.4 mg kg−1) were mixed (DMB) in a syringe and applied to the rabbits’ nasopharyngeal mucosa
after the accurate catheterization of one nostril. The onset, duration and quality
of effects including analgesia were scored using a numeric rating scale of sedation
for rabbits. Continuous monitoring of vital parameters was performed via clinical
and multiparametric recording. Physiological variables were explored using repeated
measures anova for parametric data or Friedman's test for non-parametric data. Tukey's or Dunn's
post hoc multiple comparisons test was used depending on normality. The statistical significance
was set at p < 0.05.
Results
Loss of the righting reflex, deep sedation and profound analgesia ensued simultaneously
at 1.4 ± 1.1 minutes after DMB administration. These effects lasted 45 minutes before
subsiding into moderate sedation, which lasted for an additional 25 minutes. Residual
central nervous system impairment persisted up to 100 minutes. Blood pressure dropped
progressively over time by 50%, whereas respiratory frequency decreased by 70%, consistent
with moderate hypoxemia and hypercarbia.
Conclusion and clinical relevance
The TN route is a reliable and effective means for administration of DEX, MID and
BUT to rabbits. The overall profound sedative effects and analgesic proprieties of
the DMB combination can be selectively reversed depending on the needs of the procedure.
Oxygen supplementation and careful monitoring are mandatory even in healthy subjects.
The DMB protocol should be cautiously used in rabbits with cardiovascular or respiratory
deficiencies.
Keywords
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Article info
Publication history
Accepted:
February 3,
2015
Received:
June 3,
2014
Identification
Copyright
© 2016 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Inc. All rights reserved.
