The Veterinary record1991; 129(19); 421-423; doi: 10.1136/vr.129.19.421

Comparison of the sedative effects of medetomidine and xylazine in horses.

Abstract: The sedative effects in horses of the new alpha 2 agonist medetomidine were compared with those of xylazine. Four ponies and one horse were treated on separate occasions with two doses of medetomidine (5 micrograms/kg bodyweight and 10 micrograms/kg bodyweight) and with one dose of xylazine (1 mg/kg bodyweight) given by intravenous injection. Medetomidine at 10 micrograms/kg was similar to 1 mg/kg xylazine in its sedative effect but produced more severe and more prolonged ataxia, and one animal fell over during the study. Medetomidine at 5 micrograms/kg produced less sedation but a similar degree of ataxia to 1 mg/kg xylazine.
Publication Date: 1991-11-09 PubMed ID: 1776221DOI: 10.1136/vr.129.19.421Google Scholar: Lookup
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  • Comparative Study
  • Journal Article
  • Research Support
  • Non-U.S. Gov't


This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research focuses on comparing the sedative effects of a new alpha 2 agonist, medetomidine, with those of xylazine in horses, showing that higher doses of medetomidine led to more severe and prolonged ataxia.


This research paper revolves around the comparison of the sedative effects of a newer alpha 2 agonist, medetomidine, with those of an already known sedative, xylazine, in horses. The study is conducted to understand how both these sedatives impact the horses and to ascertain the appropriate dosages of medetomidine that should be used.


  • The study was conducted on four ponies and one horse, where they were treated separately with two different doses of medetomidine, and one dose of xylazine.
  • The dose regimen included two dosages of medetomidine—5 micrograms per kilogram of bodyweight and 10 micrograms per kilogram of bodyweight and compared it with one dose of xylazine, i.e., 1 milligram per kilogram of the bodyweight.
  • All doses were administered via intravenous injection.


  • The researchers found that a 10 micrograms/kg dose of medetomidine produced a similar sedative effect to a 1 mg/kg dose of xylazine.
  • However, the higher dosage of medetomidine led to more intense and prolonged ataxia, which implies a high level of uncoordinated movement and sway in the horses.
  • In fact, one of the horses even fell over during the study, which indicates the severe effect of a higher dosage of medetomidine.
  • A lower dose (5 micrograms/kg) of medetomidine produced slightly less sedation, but the degree of ataxia was similar to that produced by 1 mg/kg of xylazine.


The research concludes with a contrast on the sedative effects of two chemical compounds—medetomidine and xylazine. The most significant takeaway is that while lower dosages of medetomidine produce sedative effects similar to xylazine, higher dosages manifest in severe and extended ataxia—much more than xylazine does. Further research would be beneficial to establish safer dosage levels for medetomidine usage in horses.

Cite This Article

Bryant CE, England GC, Clarke KW. (1991). Comparison of the sedative effects of medetomidine and xylazine in horses. Vet Rec, 129(19), 421-423.


ISSN: 0042-4900
NlmUniqueID: 0031164
Country: England
Language: English
Volume: 129
Issue: 19
Pages: 421-423

Researcher Affiliations

Bryant, C E
  • Department of Large Animal Surgery and Medicine, Royal Veterinary College, North Mymms, Hatfield.
England, G C
    Clarke, K W

      MeSH Terms

      • Animals
      • Ataxia / chemically induced
      • Ataxia / veterinary
      • Female
      • Heart Rate / drug effects
      • Horse Diseases / chemically induced
      • Horses / physiology
      • Hypnotics and Sedatives / pharmacology
      • Imidazoles / pharmacology
      • Male
      • Medetomidine
      • Xylazine / pharmacology


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