Identification of methylenecyclopropyl acetic acid in serum of European horses with atypical myopathy.
Authors: Votion D-M, van Galen G, Sweetman L, Boemer F, de Tullio P, Dopagne C, Lefère L, Mouithys-Mickalad A, Patarin F, Rouxhet S, van Loon G, Serteyn D, Sponseller B T, Valberg S J
Journal: Equine veterinary journal
Summary
# Editorial Summary: Methylenecyclopropyl acetic acid in European Atypical Myopathy European atypical myopathy (AM) has long been suspected to share a common aetiological pathway with North American seasonal pasture myopathy, a condition definitively linked to hypoglycin A toxicity from box elder (Acer negundo) seeds. Researchers analysed serum samples from affected European horses to test whether methylenecyclopropyl acetic acid (MCPA)—the toxic metabolite of hypoglycin A that accumulates during poisoning—could be detected in AM cases, mirroring findings from North American horses. Detection of MCPA in serum samples from European AM cases provided the first biochemical evidence that hypoglycin A ingestion may be the causative agent in the European syndrome, establishing a unified mechanism of disease across both continents. This identification has significant implications for prevention strategies: rather than managing AM as a mysterious seasonal condition, practitioners and owners can now focus on identifying and eliminating potential sources of hypoglycin A in pasture environments—particularly atypical maple species and related trees with toxic seeds. Recognising MCPA as a diagnostic marker also enables vets and nutritionists to counsel clients on risk periods and pasture management with greater scientific foundation than previously available.
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Practical Takeaways
- •Atypical myopathy in grazing horses may be caused by ingestion of Acer negundo (box elder) seeds; identify and remove these trees from pastures where possible
- •Recognition of the hypoglycin A toxin pathway enables targeted investigation and potential prevention strategies for affected herds
- •Horses with acute myopathy and pasture access should be considered for atypical myopathy screening, particularly during periods of seed drop from box elder trees
Key Findings
- •Methylenecyclopropyl acetic acid (MCPA), the toxic metabolite of hypoglycin A, was identified in serum of horses with European atypical myopathy
- •European atypical myopathy shares a similar pathophysiological basis with North American seasonal pasture myopathy
- •Hypoglycin A from Acer negundo seeds is implicated as the causative toxin in atypical myopathy