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Comparison of detomidine/ketamine and guaiphenesin/thiopentone for induction of anaesthesia in horses maintained with halothane
  1. R. C. Bennett, MA, VetMB, CertVA1,1,
  2. P. M. Taylor, MA, VetMB, PhD, DVA, DiplECVA, MRCVS1,2,
  3. J. C. Brearley, MA, VetMB, PhD, DVA, DiplECVA, MRCVS1,
  4. C. B. Johnson, BVSc, DVA1,3 and
  5. S. P. L. Luna, Msc, PhD, DiplECVA1,4
  1. 1 Animal Health Trust, PO Box 5, Newmarket, Suffolk CB8 7DW


This prospective clinical study compared the physiological effects of two commonly usedanaesthetic induction techniques in horses maintained with halothane. One hundred horses admitted for elective surgery were randomly allocated to receive either guaiphenesin (to effect) and thiopentone (5 mg/kg), or detomidine (20 μg/kg) and ketamine (2 mg/kg) for the induction of anaesthesia after acepromazine premedi cation. Anaesthesia was maintained with halothane in oxygen. There were no significant differences in breed, age, sex, weight, type of surgery and duration of anaesthesia between the groups. Immediately after induction of anaesthesia heart rate was higher after guaiphenesin and thiopentone, and arte- rial blood pressure was higher after detomidine and ketamine. Thereafter hypotension, often necessitating an infu- sion of dobutamine, developed in both groups. Arterial blood gases and respiratory rates were similar in the two groups. There were no significant differences between the groups in the subjectively scored quality of induction and recovery, or in recovery time.

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  • R. C. Bennett's present address is Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616-8745, USA

  • P. M. Taylor's present address is Department of Clinical Veterinary Medicine, Madingley Road, Cambridge CB3 OES

  • C. B. Johnson's present address is School of Veterinary Science, University of Bristol, Langford, Bristol BS18 7DU

  • S. P. L. Luna's present address is FMVZ, University of S. Paulo, 18618-000, Botucatu, SP, Brazil

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