Horsetalk.co.nz Researchers seek answers to an intriguing question around atypical myopathy in horses Acer pseudoplatanus) in Germany. Photo: Willow CC BY-SA 3.0 via Wikimedia Commons Understanding changes in the gut bacteria of horses may help in developing therapeutic or preventive strategies for those at risk for atypical myopathy, according to researchers. Equine atypical myopathy is a muscular disease caused by eating the seeds or seedlings of some Acer tree species. The hypoglycin A and methylenecyclopropylglycine contained in the plant material can cause a non-exercise-induced breakdown of muscle, affecting mainly postural and respiratory muscles, and the heart. The clinical picture is characterized by the sudden onset of stiffness, muscular weakness, a fast heart rate and the darkening of urine as a result of the presence of myoglobin. The disease progresses in many cases to recumbency, respiratory difficulties and death.