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Cardiovascular effects of xylazine and detomidine in horses.
Abstract: The cardiovascular effects of xylazine and detomidine in horses were studied. Six horses were given each of the following 5 treatments, at 1-week intervals: xylazine, 1.1 mg/kg, IV; xylazine, 2.2 mg/kg, IM; detomidine, 0.01 mg/kg, IV; detomidine, 0.02 mg/kg, IV; and detomidine, 0.04 mg/kg, IM. All treatments resulted in significantly decreased heart rate, increased incidence of atrioventricular block, and decreased cardiac output and cardiac index; cardiac output and cardiac index were lowest following IV administration of 0.02 mg of detomidine/kg. Mean arterial pressure was significantly reduced for various periods with all treatments; however, IV administration of 0.02 mg of detomidine/kg caused hypertension initially. Systemic vascular resistance was increased by all treatments. Indices of ventricular contractility and relaxation, +dP/dt and -dP/dt, were significantly depressed by all treatments. Significant changes were not detected in stroke volume or ejection fraction. The PCV was significantly reduced by all treatments. Respiratory rate was significantly decreased with all treatments, but arterial carbon dioxide tension did not change. Arterial oxygen tension was significantly decreased briefly with the 3 IV treatments only.
Publication Date: 1991-05-01 PubMed ID: 1854087 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.
The research investigates the impact of two drugs, xylazine and detomidine, on the cardiovascular system of horses. The study found that these substances led to significant changes in heart rate, blood pressure, and other cardiovascular indices in the horses.
Methodology and Treatments
The study was conducted on six horses who underwent five different treatments involving varying amounts and methods of administration of xylazine and detomidine. Treatments were carried out with at least a 1-week interval in between to ensure each horse completely recovered from the previous treatment. The dosages and administration method were:
- Xylazine, 1.1 mg/kg, Intravenously (IV)
- Xylazine, 2.2 mg/kg, Intramuscularly (IM)
- Detomidine, 0.01 mg/kg, IV
- Detomidine, 0.02 mg/kg, IV
- Detomidine, 0.04 mg/kg, IM
Observations and Findings
After each treatment, the various cardiovascular parameters of the horses were measured. The following significant changes were observed:
- Decreased heart rate and an increased incidence of atrioventricular block, a type of heart rhythm problem that can occur in horses.
- Reduced cardiac output and cardiac index, with the lowest values seen after administration of 0.02 mg of detomidine per kg.
- Mean arterial pressure was reduced for various periods following all treatments. The exception was the IV administration of 0.02 mg of detomidine per kg which caused initial hypertension.
- Increased systemic vascular resistance by all treatments.
- Depressed measurements on indices of ventricular contractility and relaxation, +dP/dt (maximum rate of pressure increase during systole) and -dP/dt (maximum rate of pressure decrease during diastole) respectively.
Behaviours and Volume Changes
Several more critical findings of the study included:
- No significant alterations in stroke volume (volume of blood pumped from the left ventricle per beat) or ejection fraction (percentage of blood leaving the heart each time it contracts).
- Significantly reduced packed cell volume (PCV), a measure of the volume occupied by red blood cells in the blood.
- Significantly decreased respiratory rate after all treatments, but the tension of arterial carbon dioxide remained stable.
- Arterial oxygen tension, the partial pressure of oxygen in the blood, was briefly decreased with the three treatments administered intravenously only.
Therefore, this study provides valuable insights into the cardiovascular effects of xylazine and detomidine in horses, and may help in understanding potential complications or side effects associated with their use.
Cite This Article
APA
Wagner AE, Muir WW, Hinchcliff KW.
(1991).
Cardiovascular effects of xylazine and detomidine in horses.
Am J Vet Res, 52(5), 651-657.
Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, Ohio State University, Columbus 43210.
MeSH Terms
- Analgesics / administration & dosage
- Analgesics / pharmacology
- Animals
- Electrocardiography / veterinary
- Female
- Heart Block / chemically induced
- Heart Block / veterinary
- Hematocrit / veterinary
- Hemodynamics / drug effects
- Horses / physiology
- Hypnotics and Sedatives / administration & dosage
- Hypnotics and Sedatives / pharmacology
- Imidazoles / administration & dosage
- Imidazoles / pharmacology
- Injections, Intramuscular / veterinary
- Injections, Intravenous / veterinary
- Male
- Myocardial Contraction / drug effects
- Oxygen / blood
- Respiration / drug effects
- Xylazine / administration & dosage
- Xylazine / pharmacology
Citations
This article has been cited 26 times.- Vinardell T, Elestwani S, Jamieson C, Karim E, Robin M, Glynn S, Benini R, Aleman M. Electroencephalographic evaluation under standing sedation using sublingual detomidine hydrochloride in Egyptian Arabian foals for investigation of epilepsy. J Vet Intern Med 2023 May-Jun;37(3):1209-1215.
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