Plasma endotoxin levels in horses subjected to carbohydrate induced laminitis.
Authors: Sprouse, Garner, Green
Journal: Equine veterinary journal
Summary
# Editorial Summary: Plasma endotoxin levels in horses subjected to carbohydrate induced laminitis Carbohydrate overload in horses has long been associated with laminitis, but the underlying mechanisms remained unclear when this 1988 study was undertaken. Sprouse and colleagues administered controlled carbohydrate challenges to 20 horses and monitored both clinical lameness (using Obel grading) and plasma endotoxin concentrations over 56 hours. Thirteen horses (65%) developed severe (Grade 3) lameness, and remarkably, endotoxin levels rose dramatically in 11 of these 13 animals—from baseline levels below 0.1 ng/litre to peaks ranging from 2.4 to 81.53 ng/litre. The temporal relationship between endotoxaemia and lameness was consistent across 92% of affected horses, with a distinctive two-phase endotoxin response observed in nearly half the cases: an initial peak around 32 hours followed by a second surge at approximately 48 hours post-overload. These findings substantiate the role of Gram-negative bacterial endotoxin in carbohydrate-induced laminitis pathogenesis, providing farriers, veterinarians, and nutritionists with evidence-based justification for strict feed management protocols and early intervention strategies when grain overload is suspected.
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Practical Takeaways
- •Carbohydrate overload carries significant risk of acute laminitis; monitor high-risk horses for lameness within 48–56 hours post-incident
- •Plasma endotoxin measurement may help confirm endotoxaemia-related laminitis, though levels are variable and biphasic responses are common
- •Recognition of the 32–48 hour peak endotoxin window suggests critical intervention period for management of carbohydrate-induced laminitis
Key Findings
- •65% (13/20) of horses subjected to carbohydrate overload developed Obel Grade 3 lameness within 56 hours
- •85% (11/13) of lame horses showed plasma endotoxin increases from <0.1 to 2.4–81.53 ng/litre during onset of lameness
- •92% (11/12) of horses with Obel Grade 3 lameness showed associated rises in Gram-negative endotoxin levels
- •45% (5/11) of endotoxaemic lame horses exhibited two endotoxin peaks separated by 16 hours, with first peak at ~32h and second at ~48h post-overload