Atypical Myopathy is a muscle disease which affects horses and ponies muscles, including the heart and diaphragm. It is a life threatening illness and carries a high mortality rate. There is now strong evidence it is linked to poisoning from eating Sycamore (Acer Pseudoplatanus ) leaves & seeds. It is caused by hypoglycin A, which is a toxin contained in the seeds. The toxin is not always present in every seed or every Sycamore tree, but is sometimes present in high concentrations, it is thought that certain weather conditions ( ie, long wet spells & long periods of warm dry weather ) lead to the higher concentrations.
The disease is usually found in horses / ponies where the grazing has become bare, and little or no supplementary feed is available, leading them to eat the seeds and leaves from near by trees.
Early diagnosis is very important for the animals survival. Unfortunately the symptoms are easily confused with other conditions. Clinical signs may include :- Lethargy, muscle trembling, difficulty breathing, difficulty swallowing, weakness, signs of pain, discoloured urine which may be brown or red, unable to lift their heads or even difficulty standing.
For more information :- www.bhs.org.uk/ATMleaflet