Cardiopulmonary function and intestinal blood flow in anaesthetised, experimentally endotoxaemic horses given a constant rate infusion of dexmedetomidine.
Authors: Hector Rachel C, Rezende Marlis L, Nelson Brad B, Monnet Eric
Journal: Equine veterinary journal
Summary
# Dexmedetomidine in Endotoxaemic Anaesthetised Horses: Implications for Colic Surgery Endotoxaemia represents a major complication in equine colic, triggering inflammatory cascades that compromise cardiovascular stability and organ perfusion during surgery. Researchers administered lipopolysaccharide (LPS) intravenously to 13 anaesthetised horses—seven serving as controls and six receiving dexmedetomidine infusion (1.75 mcg/kg loading dose followed by 1.75 mcg/kg/hour)—whilst measuring cardiac index via thermodilution, mesenteric blood flow, and arterial blood gases over a 390-minute period. Although dexmedetomidine temporarily reduced intestinal blood flow and cardiac index immediately after the loading dose, these parameters returned to baseline levels during the maintenance infusion, whilst the drug enabled approximately 40% reduction in sevoflurane requirements and significantly attenuated metabolic acidosis (base excess improved from −5.3 to +2.0 mmol/L) and maintained better renal function (creatinine 115 versus 195 µmol/L). For equine practitioners managing colic cases requiring surgery, this work suggests that dexmedetomidine infusion combined with reduced volatile anaesthetic dosing may protect against endotoxin-induced cardiovascular deterioration without creating sustained haemodynamic compromise, though the controlled experimental environment cannot fully replicate the complexity of clinical colic presentations.
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Practical Takeaways
- •Dexmedetomidine combined with reduced sevoflurane dosing may help preserve organ function and acid-base balance during emergency colic surgery in endotoxaemic horses
- •The transient haemodynamic depression after dexmedetomidine loading resolves with continued infusion, making it a viable option for high-risk anaesthetic cases
- •Note that these findings are from experimental endotoxaemia under controlled conditions; clinical applicability to naturally occurring colic requires further investigation
Key Findings
- •Dexmedetomidine infusion with 50% sevoflurane dose reduction did not cause sustained negative effects on cardiac index or intestinal blood flow in endotoxaemic horses despite transient decreases after loading dose
- •Dexmedetomidine treatment resulted in significantly lower creatinine (115 vs 195 µmol/L) and preserved acid-base status (bicarbonate 29.7 vs 23 mmol/L, base excess 2.0 vs -5.3 mmol/L) compared to LPS controls
- •Sevoflurane requirements were reliably reduced by approximately 40% with dexmedetomidine infusion while maintaining stable plasma concentrations throughout the study period