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Atypical Myopathy


Atypical myopathy is a severe and frequently fatal disease. It was discovered that the sycamore tree is the cause in Europe. Research is still on going to clarify risk factors, and toxin levels in other plant species.

Cases are at their highest during the autumn especially after windy weather when many seeds have fallen on pasture.

The disease causes severe damage to muscles which causes weakness, pain and difficulty breathing. Approximately 25% of these cases in Europe survive with prompt recognition and action.


Clinical signs:

Dullness and lethargy

Severe generalised weakness

Dark brown urine

Tremors may show colic signs

Increased respiratory rate and effort.



Horses with atypical myopathy are treated symptomatically which means we cannot directly attack the causal agent of the disease, but we take steps to support the horse and keep them comfortable. This is mostly through providing pain relief and intravenous fluid therapy.


Preventing Atypical Myopathy:

Avoiding sycamore seeds is important to prevent atypical myopathy. Fencing off affected areas under trees, picking up seeds and providing extra hay to reduce foraging seeds may all be helpful strategies.

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