Atypical Myopathy Warning

With Autumn upon us, please check your pastures for sycamore tree seeds and leaves. Leaves and fallen seeds contain a toxin called hypoglycin A (HGA) which causes Atypical Myopathy (sycamore poisoning) in horses when ingested. The toxin HGA slows or stops energy production in muscles and the heart.

There are a number of things you can do to help prevent ingestion of sycamore seeds & leaves and therefore help to prevent Atypical Myopathy (AM):

  • Ideally moving your horses to pasture where sycamore trees are not in danger of dropping seeds or leaves, although we are aware this is not always possible (the “helicopter” seeds can travel up to 200 yards). Alternatively, fence off any areas of the pasture where sycamore seeds and leaves have fallen
  • Removing sycamore seeds / leaves from pastures and pulling up (if possible) sycamore seedlings – seedlings should be carefully disposed of because dead seedlings (including seedlings killed using herbicides) are still poisonous
  • Providing supplementary hay / haylage, especially when grazing is poor. However, avoid leaving wet hay on the ground as this can increase the risk
  • Provide supplementary concentrate feeding
  • Reduce time spent at pasture

Not all horses on problem pastures are susceptible (probably depending on genetic factors), but currently it is not possible to tell which horses are high risk.

Atypical myopathy signs include:

  • General weakness  – difficulty walking and breathing
  • Sudden collapse and inability to stand
  • Depression – holding head low
  • Muscle tremors / trembling
  • Signs of colic (but often still have a good appetite)
  • Brown or dark red urine

Blood tests can confirm the diagnosis. Sadly the disease is frequently fatal (over 50% of affected horses do not survive), especially if the horse becomes recumbent and unable to get up. However treatment can be successful in mild cases and if started early enough – if horses survive the first few days then they have a higher chance of surviving, however full recovery can take several months.

If you suspect your horse is showing signs of Atypical Myopathy, please contact Bell Equine on 01622 813700 immediately – remember that the earlier we can diagnose the disease and initiate treatment, the better the chances of survival.

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