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Sedative and cardiopulmonary effects of dexmedetomidine infusions randomly receiving, or not, butorphanol in standing horses
  1. Luíza Quintão Medeiros, DVM, MSc1,
  2. Miguel Gozalo-Marcilla, DVM, PhD, Dip. ECVAA2,
  3. Polly M Taylor, DVM, PhD, Dp. ECVAA3,
  4. Daniela Campagnol, DVM, MSc, PhD1,
  5. Flávia Augusta de Oliveira, DVM, MSc, PhD1,
  6. Marcos Jun Watanabe, DVM, MSC, PhD2 and
  7. Antonio José de Araujo Aguiar, DVM, MSc, PhD2
  1. 1 Graduate Program in Anaesthesiology, Medical School of Botucatu, UNESP—Univ Estadual Paulista, Botucatu-SP, Brazil
  2. 2 Department of Veterinary Surgery and Anaestesiology, Faculty of Veterinary Medicine and Animal Science, UNESP – Univ Estadual Paulista, Botucatu-SP, Brazil
  3. 3 Taylor Monroe, Ely, UK
  1. E-mail for correspondence; ajaguiar{at}


Dexmedetomidine (DEX) alone, or combined with butorphanol (BUT), may be administered by constant rate infusions (CRIs) in standing horses. This blinded, randomised, crossover study in six healthy adult horses aimed to determine the sedative and cardiopulmonary effects of DEX (dexmedetomidine (3.5 µg/kg+5 µg/kg/hour CRI) and DEX/BUT (dexmedetomidine (3.5 µg/kg+3.5 µg/kg/hour CRI) and butorphanol (20 µg/kg+24 µg/kg/hour CRI)). Head height above ground (HHAG), ataxia, responses to tactile/auditory stimuli and cardiopulmonary variables were recorded before, at 5/15/30/60/90 minutes and after CRIs terminated (15/30/60 minutes). Repeated measures analysis of variance with Tukey-Kramer test were used for cardiopulmonary values (mean±SD) and HHAG reduction (per cent), and Friedman’s and Dunn’s for non-parametric data (P<0.05). Maximum HHAG reductions of 54 per cent (DEX) and 58 per cent (DEX/BUT) occurred at 15 minutes, with ataxia for 15 minutes in both treatments. Responses to stimuli were reduced for 30 minutes in both treatments, and auditory up to 60 minutes in DEX. Cardiopulmonary effects typical of α2-agonists were observed, with no differences between treatments. At the doses and rates reported here, both regimens provided clinically sufficient sedation for only 30 minutes.

  • butorphanol
  • constant rate infusion
  • dexmedetomidine
  • equine
  • standing horse
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  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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