Analgesic, hemodynamic, and respiratory effects of caudal epidurally administered xylazine hydrochloride solution in mares.
Abstract: To examine effects of 0.25 mg of xylazine/kg of body weight diluted to a total volume of 6 ml/450 kg with sterile 0.9% NaCl, administered into the epidural space of the sacrococcygeal joint on perineal analgesia, sedation, ataxia, and respiratory and cardiovascular function in standing mares. Methods: Randomized, blinded study, using xylazine (treatment) and 0.9% NaCl (controls). At least 2 weeks elapsed between the treatments. Methods: Eight healthy mares. Methods: Blood samples were drawn. Systemic hemodynamics were determined, including cardiac output and pulmonary arterial, systemic arterial, and right atrial pressures. Two-way ANOVA with repeated measures was used to detect significant (P < 0.05) differences between mean scores of analgesia, sedation, ataxia, and cardiorespiratory variables before and during a 3-hour testing period. Analgesia was determined by lack of sensory perception to electrical stimulation at the perineal dermatome and no response to needle prick stimulation extending from coccyx to S3 dermatomes. Sedation was determined by head ptosis. Results: Epidurally administered xylazine induced variable bilateral caudal analgesia extending from coccyx to S3, with minimal sedation, ataxia, and cardiovascular and respiratory depression in standing mares. Analgesia was attained at 15 +/- 6 minutes and lasted for 165 to over 180 minutes. Heart and respiratory rates, systolic, diastolic, and mean arterial blood pressure, PCV, hemoglobin concentration, arterial oxygen content, and oxygen transport were decreased after xylazine, but not 0.9% NaCl, treatment. Cardiac output, stroke volume, mean right atrial pressure, mean pulmonary artery pressure, systemic vascular resistance, pulmonary vascular resistance, arterial and mixed venous pH and gas tensions (PO2 and PCO2), oxygen consumption, blood temperature, and rectal temperature did not change significantly (P 2 hours) caudal analgesia with minimal sedation, ataxia, and circulatory and respiratory disturbances in conscious, standing mares.
Publication Date: 1996-02-01 PubMed ID: 8633807
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- Clinical Trial
- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
Summary
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This research tests the effects of injecting a specific dose of xylazine, a sedative and analgesic, into the spine in horses. The results indicate that this procedure is safe and can successfully provide pain relief for several hours with minimal side effects.
Research Design and Methodology
The study used a randomised, blind design to measure:
- Perineal analgesia effectiveness, meaning numbness or loss of feeling in the perineal area.
- Sedation and ataxia (lack of muscle control) effects.
- Impacts on the cardiovascular (circulatory) and respiratory systems.
Eight healthy female horses (mares) were given a 0.25 mg/kg dose of xylazine, which was mixed with a sterilised 0.9% sodium chloride (NaCl) solution until the total volume was 6ml/450kg. This was then injected into the spinal canal at the sacrococcygeal joint, which is located at the base of the spine.
Blood samples were taken before and during a three-hour testing period following the xylazine administration. Various cardiovascular and systemic hemodynamic factors were measured, like cardiac output and several blood pressures.
Analysis and Results Overview
The post-treatment measurements were statistically analysed to look for significant changes and differences between:
- The control experiment with 0.9% NaCl only.
- The experiment with xylazine treatment.
These included measures of:
- Analgesia effectiveness
- Sedation levels, judged by drooping of the head (ptosis)
- Physical coordination (ataxia)
- Respiratory rates and arterial blood pressure
- Packed Cell Volume (PCV) and hemoglobin concentration – markers of anaemia and oxygen carrying capacity of the blood
- Arterial oxygen content and oxygen transport
Key Findings
The study determined that epidural injection of xylazine:
- Induced analgesia (pain reduction) from 15 minutes post-injection, which lasted for 165 to over 180 minutes.
- Caused minimal sedation and ataxia (loss of muscle coordination) in standing horses.
- Decreased heart and respiratory rates, and arterial blood pressure. These effects were not observed when the control solution was administered.
- Did not significantly change cardiac output, stroke volume, and other measures necessary for normal functioning of cardiovascular and respiratory systems.
The research concludes that xylazine can be administered epidurally at this dose for prolonged analgesia, with minimal side effects, in conscious, standing horses.
Cite This Article
APA
Skarda RT, Muir WW.
(1996).
Analgesic, hemodynamic, and respiratory effects of caudal epidurally administered xylazine hydrochloride solution in mares.
Am J Vet Res, 57(2), 193-200.
Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, Ohio State University, Columbus 43210-1089, USA.
MeSH Terms
- Analysis of Variance
- Anesthetics / administration & dosage
- Anesthetics / pharmacology
- Anesthetics / therapeutic use
- Animals
- Blood Gas Analysis
- Blood Pressure / drug effects
- Blood Pressure / physiology
- Body Temperature / drug effects
- Body Temperature / physiology
- Cardiac Output / drug effects
- Cardiac Output / physiology
- Cardiovascular Physiological Phenomena
- Cardiovascular System / drug effects
- Double-Blind Method
- Female
- Hematocrit
- Hemodynamics / drug effects
- Hemodynamics / physiology
- Horses / metabolism
- Horses / physiology
- Hydrogen-Ion Concentration
- Injections, Epidural / veterinary
- Oxygen Consumption / drug effects
- Oxygen Consumption / physiology
- Pain / drug therapy
- Pain / physiopathology
- Respiration / drug effects
- Respiration / physiology
- Stroke Volume / drug effects
- Stroke Volume / physiology
- Xylazine / administration & dosage
- Xylazine / pharmacology
- Xylazine / therapeutic use
Citations
This article has been cited 4 times.- Vullo C, Tambella AM, Meligrana M, Catone G. Analgesic and Sedative Effects of Epidural Lidocaine-Xylazine in Elective Bilateral Laparoscopic Ovariectomy in Standing Mule Mares. Animals (Basel) 2021 Aug 17;11(8).
- Kinjavdekar P, Singh GR, Amarpal, Aithal HP, Pawde AM. Clinicophysiological effects of spinally administered ketamine and its combination with xylazine and medetomidine in healthy goats. Vet Res Commun 2007 Oct;31(7):847-61.
- DeRossi R, Sampaio BF, Varela JV, Junqueira AL. Perineal analgesia and hemodynamic effects of the epidural administration of meperidine or hyperbaric bupivacaine in conscious horses. Can Vet J 2004 Jan;45(1):42-7.
- Sobhy A, Nomir AG, Hamed MA, Abumandour MMA, El-Kammar M. Efficacy of caudal epidural injection of Xylazine-Lidocaine HCl and detomidine-lidocaine HCl in domestic horses (Equus ferus caballus). BMC Vet Res 2025 May 28;21(1):385.
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