Plasma endotoxin in horses presented to an equine referral hospital: correlation to selected clinical parameters and outcomes.
Authors: Senior J M, Proudman C J, Leuwer M, Carter S D
Journal: Equine veterinary journal
Summary
# Editorial Summary Endotoxaemia is routinely suspected in equine colic cases based on clinical presentation alone, yet direct measurement of plasma lipopolysaccharide (LPS) remains uncommon in clinical practice, leaving practitioners with limited evidence on which to base prognosis and management decisions. Senior and colleagues measured plasma LPS levels in 234 horses admitted to a referral hospital using a validated kinetic chromogenic Limulus amoebocyte lysate assay, collecting samples on admission and daily for up to four days, then correlated findings with clinical parameters including heart rate and packed cell volume alongside recorded outcomes. LPS was detected in 26.5% of all horses studied and 29% of colic-presenting cases; whilst colic horses were significantly more likely to have detectable LPS than non-colic cases (P = 0.037), only a minority of colic presentations showed LPS positivity, and horses meeting clinical criteria for endotoxaemia were ten times more likely to test positive (odds ratio 0.10). Importantly, horses with detectable plasma LPS had significantly increased mortality risk (P = 0.045), and LPS positivity correlated positively with packed cell volume, suggesting haemoconcentration may be a useful clinical indicator. These findings challenge the assumption that clinical endotoxaemia is present in most colic cases and indicate that actual LPS detection, when available, provides genuine prognostic value beyond traditional clinical parameters alone.
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Practical Takeaways
- •Clinical signs alone are unreliable for diagnosing endotoxaemia in colic cases—actual LPS detection occurs in less than one-third of colicky horses despite higher suspicion rates, so laboratory confirmation should guide treatment decisions
- •Detectable plasma endotoxin is a significant mortality predictor; horses with positive LPS results warrant intensive monitoring and aggressive supportive care
- •Packed cell volume elevation alongside colic may indicate endotoxaemia; combining clinical assessment with LPS testing and PCV monitoring improves prognostic accuracy
Key Findings
- •Plasma endotoxin (LPS) was detected in 26.5% of all horses and 29% of colic cases, despite clinical endotoxaemia being more frequently presumed
- •Horses with detectable LPS were significantly more likely to die in hospital compared to LPS-negative horses (P = 0.045)
- •LPS detection was 10 times more likely in horses meeting clinical endotoxaemia criteria (OR 0.10 for non-endotoxaemic cases)
- •Increased LPS levels positively correlated with packed cell volume and mortality risk in colic cases