Myonecrosis in three horses with colic: evidence for endotoxic injury.
Authors: Valentine B A, Löhr C V
Journal: The Veterinary record
Summary
# Editorial Summary: Myonecrosis in Colic—An Endotoxic Mechanism When horses present with severe colic alongside elevated muscle enzymes (creatine kinase and aspartate aminotransferase), clinicians typically suspect primary muscle trauma or recumbency-related myopathy; however, Valentine and Löhr's 2007 postmortem examination of three colic cases revealed an alternative pathway to myonecrosis. Despite clinical and biochemical evidence of endotoxaemia—paired with markedly elevated serum muscle markers—gross inspection and histological analysis showed no trauma to the skeletal musculature, yet the semimembranosus muscles displayed characteristic segmental myofibre necrosis in various stages of degeneration. The authors identified endotoxin-induced direct muscle injury as the culprit rather than secondary ischaemic or mechanical damage, establishing that lipopolysaccharide release from colonic pathology (ulcerative colitis, pyloric ulceration and stenosis, sand impaction, and faecalith obstruction in these cases) can trigger myonecrosis independent of physical insult. For practitioners managing colic cases with disproportionately severe muscle enzyme elevation, this work underscores the need to recognise systemic endotoxaemia itself as a cause of myopathy—not merely an incidental finding—and highlights that aggressive endotoxin management may warrant consideration even in horses without obvious recumbency or compression injury. Understanding this mechanism may refine both prognostic assessment and therapeutic priorities in endotoxic colic patients.
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Practical Takeaways
- •Horses with colic and signs of endotoxaemia may develop muscle damage independent of trauma; elevated muscle enzymes warrant investigation for systemic endotoxic effects
- •Severe gastrointestinal disease (ulcerative colitis, obstruction) can cause systemic endotoxaemia leading to myonecrosis, which may contribute to poor recovery or secondary complications
- •Post-colic monitoring should include muscle enzyme assessment to identify endotoxin-induced myonecrosis, which may affect prognosis and rehabilitation
Key Findings
- •Three horses with colic and clinical endotoxaemia showed elevated serum creatine kinase and aspartate aminotransferase activities without evidence of muscle trauma
- •Postmortem examination revealed scattered acute to subacute segmental myofibre necrosis in the semimembranosus muscles
- •Myonecrosis pattern was consistent with endotoxin-induced muscle injury rather than traumatic injury