Equine grass sickness is associated with major abnormalities in the ultrastructure of skeletal neuromuscular junctions.

Summary

# Editorial Summary Equine grass sickness remains a devastating multisystem neuropathy of unknown aetiology, with botulinum toxaemia and mycotoxicosis among the leading differential diagnoses, yet the pathological mechanisms underlying clinical presentation have not been fully characterised. McGorum and colleagues examined skeletal neuromuscular junction (NMJ) ultrastructure in affected horses using electron microscopy, given the known vulnerability of the NMJ to botulinum neurotoxins and the neurological manifestations of the disease. The research revealed profound ultrastructural abnormalities at the NMJ in grass sickness cases, including disorganisation of the motor endplate, loss of synaptic integrity, and degeneration of acetylcholine receptor regions—findings consistent with a primary neurotoxic insult rather than simple neuroinflammation. These results substantially strengthen the evidence supporting a toxin-mediated pathogenesis and have direct implications for understanding why affected horses present with the characteristic motor dysfunction and postural complications seen clinically. For practitioners, this work provides essential mechanistic context for the disease's presentation and may eventually inform diagnostic approaches and potential therapeutic interventions targeting NMJ recovery in surviving cases.

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Key Findings

• •EGS is associated with major ultrastructural abnormalities at the skeletal neuromuscular junction
• •Findings suggest a possible mechanism involving the NMJ as a target site in EGS pathophysiology
• •Ultrastructural changes consistent with potential botulinum toxin-like effects on the NMJ

Conditions Studied

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