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Veterinary sciences2026; 13(1); 77; doi: 10.3390/vetsci13010077

Effect of a Constant Rate Infusion of Ketamine on a Variable Rate Infusion of Xylazine in Standing Horses Undergoing Ventriculocordectomy and Laryngoplasty.

Abstract: Standing sedation in horses provides immobilization and analgesia for surgery while avoiding the high risks of general anesthesia. Ketamine at subanesthetic doses may enhance sedation and reduce xylazine requirements, but evidence in clinical settings is limited. In a randomized blinded trial, we evaluated whether adding a low-dose ketamine infusion could reduce the xylazine dose required for effective sedation during standing ventriculocordectomy and laryngoplasty. Fifty-one horses were randomly assigned to sedation with xylazine alone (SX group) or xylazine plus ketamine (KX group) in a continuous rate infusion. The ketamine group received ketamine (0.25 mg/kg intravenous (IV) bolus followed by 0.5 mg/kg/h infusion), while xylazine was administered in both groups via a titrated infusion to effect according to the Ghent Sedation Algorithm. Sedation depth, ataxia, surgical condition scores, and cardiorespiratory parameters were recorded. Data are presented as median (25th-75th percentiles) and estimated effect with 95% confidence intervals (CI). Statistical significance was set at < 0.05 and at 95% CIs excluding zero. The addition of ketamine did not significantly reduce xylazine requirements (0.9 (0.7-1.3) vs. 0.8 (0.5-1.1) mg/kg/h for SX and KX, respectively; = 0.139). However, horses receiving ketamine (KX) achieved deeper sedation (Estimate = 2.74; 95% CI: 0.95 to 4.63) with no differences in ataxia or surgical conditions. Cardiorespiratory variables remained stable in both groups, and no adverse events occurred. In conclusion, adding a subanesthetic ketamine infusion improved sedation depth without adverse effects but did not significantly reduce the xylazine requirement.
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Publication Date: 2026-01-12 PubMed ID: 41600733PubMed Central: PMC12846665DOI: 10.3390/vetsci13010077Google Scholar: Lookup
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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.

Overview

  • This study investigated whether adding a low-dose ketamine infusion could reduce the amount of xylazine needed for effective sedation in standing horses undergoing specific surgeries (ventriculocordectomy and laryngoplasty).
  • The results showed that adding ketamine enhanced sedation depth without reducing xylazine dosage requirements or causing adverse effects.

Background and Purpose

  • Standing sedation is preferred in horses for certain surgeries to avoid risks linked with general anesthesia.
  • Xylazine is a sedative commonly used; however, it can cause side effects, and minimizing its dosage is desirable.
  • Ketamine, at subanesthetic doses, has been suggested to enhance sedation and possibly reduce the needed xylazine dose, but this was not well documented in clinical settings prior to this study.
  • The purpose of the research was to assess if a constant ketamine infusion alongside a variable xylazine infusion would reduce the overall xylazine dose while maintaining safe and effective sedation.

Study Design and Methods

  • A randomized, blinded clinical trial was conducted involving 51 horses undergoing standing ventriculocordectomy and laryngoplasty surgeries.
  • Participants were assigned to:
    • SX group: sedation with variable rate xylazine infusion alone.
    • KX group: sedation with xylazine infusion plus a constant ketamine infusion.
  • Ketamine regimen in the KX group:
    • Initial intravenous bolus of 0.25 mg/kg.
    • Continuous rate infusion of 0.5 mg/kg/hour.
  • Xylazine infusion in both groups was titrated according to the Ghent Sedation Algorithm to achieve adequate sedation.
  • Parameters monitored included:
    • Sedation depth.
    • Ataxia (uncoordinated movement).
    • Surgical conditions (quality of the operative environment and immobility).
    • Cardiorespiratory variables.
    • Any adverse events.
  • Data were reported as medians with interquartile ranges or as estimated effects with 95% confidence intervals.
  • Statistical significance was set at p < 0.05 and 95% confidence intervals not crossing zero.

Key Findings

  • Xylazine dosage:
    • SX group median dose: 0.9 mg/kg/h (range 0.7-1.3).
    • KX group median dose: 0.8 mg/kg/h (range 0.5-1.1).
    • Difference was not statistically significant (p = 0.139), indicating ketamine did not significantly reduce xylazine requirements.
  • Sedation depth:
    • KX group achieved significantly deeper sedation (estimated effect = 2.74, 95% CI: 0.95 to 4.63).
  • Ataxia and surgical conditions:
    • No significant differences between groups, indicating ketamine did not worsen ataxia or surgical environment quality.
  • Cardiorespiratory parameters:
    • Remained stable throughout the procedures in both groups.
  • Adverse events:
    • No adverse events were recorded in either group during sedation or surgery.

Conclusions and Implications

  • Adding a low-dose infusion of ketamine to xylazine sedation enhances the depth of sedation in standing horses undergoing specific surgeries.
  • However, this addition does not significantly decrease the required dose of xylazine to achieve sedation.
  • The combination was safe and well tolerated with no adverse cardiorespiratory effects or increased ataxia.
  • This suggests that while ketamine can improve sedation quality, it may not reduce sedative drug load as initially hypothesized.
  • Veterinarians may consider ketamine as an adjunct to achieve deeper sedation for standing surgeries, balancing sedation depth and safety.

Cite This Article

APA
Medina-Bautista F, Morgaz J, Quirós-Carmona S, Caravaca-Paredes ME, Navarrete-Calvo R, Medina ALS, Gómez-Villamandos R, Granados MDM. (2026). Effect of a Constant Rate Infusion of Ketamine on a Variable Rate Infusion of Xylazine in Standing Horses Undergoing Ventriculocordectomy and Laryngoplasty. Vet Sci, 13(1), 77. https://doi.org/10.3390/vetsci13010077

Publication

Veterinary sciences
ISSN: 2306-7381
NlmUniqueID: 101680127
Country: Switzerland
Language: English
Volume: 13
Issue: 1
PII: 77

Researcher Affiliations

Medina-Bautista, Francisco
  • Section of Anesthesiology, Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Universidad de Córdoba, 14014 Córdoba, Spain.
Morgaz, Juan
  • Section of Anesthesiology, Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Universidad de Córdoba, 14014 Córdoba, Spain.
Quirós-Carmona, Setefilla
  • Section of Anesthesiology, Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Universidad de Córdoba, 14014 Córdoba, Spain.
Caravaca-Paredes, María Esther
  • Section of Anesthesiology, Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Universidad de Córdoba, 14014 Córdoba, Spain.
Navarrete-Calvo, Rocío
  • Section of Anesthesiology, Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Universidad de Córdoba, 14014 Córdoba, Spain.
Medina, Antonia Lucía Sánchez de
  • Section of Anesthesiology, Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Universidad de Córdoba, 14014 Córdoba, Spain.
Gómez-Villamandos, Rafael
  • Section of Anesthesiology, Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Universidad de Córdoba, 14014 Córdoba, Spain.
Granados, María Del Mar
  • Section of Anesthesiology, Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Universidad de Córdoba, 14014 Córdoba, Spain.

Conflict of Interest Statement

The authors declare no conflicts of interest.

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