Effect of yohimbine on detomidine induced changes in behavior, cardiac and blood parameters in the horse

Heather K Knych, Vanessa Covarrubias, Eugene Steffey

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Objective To describe selected pharmacodynamic effects of detomidine and yohimbine when administered alone and in sequence. Study design Randomized crossover design. Animals Nine healthy adult horses aged 9±4years and weighing 561±56kg. Methods Three dose regimens were employed in the current study. 1) 0.03mgkg-1 detomidine IV, 2) 0.2mgkg-1 yohimbine IV and 3) 0.03mgkg-1 detomidine IV followed 15minutes later by 0.2mgkg-1 yohimbine IV. Each horse received all three treatments with a minimum of 1week between treatments. Blood samples were obtained and plasma analyzed for detomidine and yohimbine concentrations by liquid chromatography-mass spectrometry. Behavioral effects, heart rate and rhythm, glucose, packed cell volume and plasma proteins were monitored. Results Yohimbine rapidly reversed the sedative effects of detomidine in the horse. Additionally, yohimbine effectively returned heart rate and the percent of atrio-ventricular conduction disturbances to pre-detomidine values when administered 15minutes post-detomidine administration. Plasma glucose was significantly increased following detomidine administration. The detomidine induced hyperglycemia was effectively reduced by yohimbine administration. Effects on packed cell volume and plasma proteins were variable. Conclusions and clinical relevance Intravenous administration of yohimbine effectively reversed detomidine induced sedation, bradycardia, atrio-ventricular heart block and hyperglycemia.

Original languageEnglish (US)
Pages (from-to)574-583
Number of pages10
JournalVeterinary Anaesthesia and Analgesia
Issue number6
StatePublished - Nov 2012


  • Alpha-2 adrenergic agonist
  • Antagonist
  • Cardiac arrhythmias
  • Detomidine
  • Equine
  • Yohimbine

ASJC Scopus subject areas

  • veterinary(all)


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