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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 The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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.
Introduction
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.
Methodology
- 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.
Findings
- 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.
Conclusion
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
APA
Bryant CE, England GC, Clarke KW.
(1991).
Comparison of the sedative effects of medetomidine and xylazine in horses.
Vet Rec, 129(19), 421-423.
https://doi.org/10.1136/vr.129.19.421 Publication
Researcher Affiliations
- Department of Large Animal Surgery and Medicine, Royal Veterinary College, North Mymms, Hatfield.
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
Citations
This article has been cited 14 times.- Kerr CL, Keating SCJ, Arroyo LG, Viel L. Cardiopulmonary effects and recovery characteristics associated with 2 sedative protocols for assisted ventilation in healthy neonatal foals. Can J Vet Res 2021 Oct;85(4):251-260.
- Stover BC, Caulkett NA. Anesthesia techniques used for field castration of 10 intractable horses. Can Vet J 2021 May;62(5):501-504.
- Wiederkehr A, Barbarossa A, Ringer SK, Jörger FB, Bryner M, Bettschart-Wolfensberger R. Clinical Randomized Comparison of Medetomidine and Xylazine for Isoflurane Balanced Anesthesia in Horses. Front Vet Sci 2021;8:603695.
- de Oliveira AR, Gozalo-Marcilla M, Ringer SK, Schauvliege S, Fonseca MW, Trindade PHE, Puoli Filho JNP, Luna SPL. Development, Validation, and Reliability of a Sedation Scale in Horses (EquiSed). Front Vet Sci 2021;8:611729.
- Kanda T, Gotoh M, Makino A, Furumoto K, Shimizu Y, Itoi T, Maeta N, Furukawa T. Effect of Different Doses of Atipamezole on Reversal of Medetomidine-Induced Tear-Flow Decrease in Rats. Vet Sci 2020 Dec 3;7(4).
- Kanda T, Mizoguchi Y, Furumoto K, Shimizu Y, Maeta N, Furukawa T. Effect of Intramuscular Medetomidine Administration on Tear Flow in Rats. Vet Sci 2020 Apr 13;7(2).
- Aoki M, Wakuno A, Kushiro A, Mae N, Kakizaki M, Nagata SI, Ohta M. Evaluation of total intravenous anesthesia with propofol-guaifenesin-medetomidine and alfaxalone-guaifenesin-medetomidine in Thoroughbred horses undergoing castration. J Vet Med Sci 2017 Dec 22;79(12):2011-2018.
- Umar MA, Fukui S, Kawase K, Itami T, Yamashita K. Cardiovascular effects of total intravenous anesthesia using ketamine-medetomidine-propofol (KMP-TIVA) in horses undergoing surgery. J Vet Med Sci 2015 Mar;77(3):281-8.
- Seo JP, Son WG, Gang S, Lee I. Sedative and analgesic effects of intravenous xylazine and tramadol on horses. J Vet Sci 2011 Sep;12(3):281-6.
- Cruz FS, Carregaro AB, Machado M, Antonow RR. Sedative and cardiopulmonary effects of buprenorphine and xylazine in horses. Can J Vet Res 2011 Jan;75(1):35-41.
- Gomes ÉR, Felix LA, Gonzaga LWF, da Silva NFD, Soares BCF, de Almeida JVFC, Souza GP, Pereira RN, Taffarel MO, Ferrante M. Sedative effects of detomidine and midazolam combination in horses. Open Vet J 2025;15(7):2938-2947.
- Durney P, Kahoud JL, Warrick-Stone T, Montesi M, Carter M, Butt S, Mencia AM, Omoregie L, Shah M, Bloomfield M, Tomasko N, Jaffe R, Herens A, Korn WR, Alexander K, Stickle D, Goodstein D, Weinstein LC, London KS. Biochemical Identification and Clinical Description of Medetomidine Exposure in People Who Use Fentanyl in Philadelphia, PA. Int J Mol Sci 2025 Jul 13;26(14).
- Izquierdo-Moreno J, de Paz MI, Manso-Díaz G, Villalba-Orero M, López-Sanromán J. Correlation between kinematic parameters, ataxia and ground-to-lip distance in detomidine sedated horses. Equine Vet J 2025 May;57(3):798-805.
- de Oliveira AR, Gozalo-Marcilla M, Ringer SK, Schauvliege S, Fonseca MW, Esteves Trindade PH, Prospero Puoli Filho JN, Luna SPL. Development and validation of the facial scale (FaceSed) to evaluate sedation in horses. PLoS One 2021;16(6):e0251909.
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