The lipopolysaccharide model for the experimental induction of transient lameness and synovitis in Standardbred horses.
Authors: Van de Water E, Oosterlinck M, Korthagen N M, Duchateau L, Dumoulin M, van Weeren P R, Olijve J, van Doorn D A, Pille F
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Researchers investigating lameness models in horses discovered that the lipopolysaccharide (LPS) induction protocol used successfully in Warmbloods failed to produce consistent lameness in Standardbreds, despite triggering synovitis. Through a dose-escalation trial in eight healthy Standardbred horses, they determined that 10 endotoxin units (EU) of *E. coli* O55:B5 injected intra-articularly into the middle carpal joint reliably induced mild-to-moderate lameness peaking at 4 hours post-injection and resolving within 48 hours, measured via visual assessment, inertial sensors and pressure plate analysis alongside synovial fluid biomarkers including prostaglandin E2. Meloxicam pre-treatment abolished the lameness response and significantly reduced synovial PGE2 elevation, confirming the inflammatory mechanism underpinning the model. This standardised LPS protocol offers equine professionals a reproducible experimental framework for investigating acute joint inflammation and therapeutic interventions in Standardbreds, a breed previously underrepresented in lameness research, whilst the predictable dose-response relationship and rapid resolution make it practical for controlled clinical trials without prolonged welfare concerns.
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Practical Takeaways
- •This LPS model provides a reliable experimental tool for studying transient joint inflammation and lameness in Standardbred horses, useful for evaluating new anti-inflammatory treatments
- •NSAIDs (meloxicam) effectively prevent lameness manifestation even when synovitis develops, suggesting prostaglandin-mediated pain is key to clinical expression
- •The rapid onset (4 hours) and resolution (48 hours) of lameness in this model makes it suitable for short-term intervention studies
Key Findings
- •A dose of 10 endotoxin units (EU) of E. coli O55:B5 LPS consistently induced mild to moderate transient lameness in Standardbred horses when injected intra-articularly into the middle carpal joint
- •Maximal lameness occurred at 4 hours post-injection (PIH) with complete resolution by 48 hours PIH
- •Meloxicam pre-treatment completely prevented lameness development despite synovitis induction
- •Synovial prostaglandin E2 (PGE2) levels were significantly elevated at PIH 8 and 24 in untreated horses but suppressed with meloxicam pre-treatment