Atypical Myopathy – Danger to Horses

As autumn comes to the British Isles, bringing with it some wet and windy weather, it seems our horses are once again facing huge danger from outbreaks of Atypical Myopathy. Caused by a toxin (Hypoglycin A) found in sycamore seeds, the condition has an estimated mortality rate of 75-90%. Please, please check your fields for sycamore seeds – they can travel huge distances on the wind, so don’t rely on the field being clear simply because there not being any sycamore trees round the boundary. If you find any, move your horses urgently before doing anything to try and clear the seeds.

Symptoms of AM include sudden stiffness, muscle tremors, collapse, colic-like signs, low temperature, increased heart rate and dark urine. The BHS has put together an information leaflet, which can be found at

Please do familiarise yourself with the symptoms as early action may prevent a fatality.

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