As veterinarians in the United Kingdom see the year’s first cases of fatal muscle disease in horses that have eaten sycamore seeds, the British Veterinary Association (BVA) and British Equine Veterinary Association (BEVA) are warning horse owners to take extra precautions as autumn winds bring down seeds into pastures.

Sycamore seeds are toxic to horses and can cause seasonal pasture myopathy (SPM), previously known as atypical myopathy, a fatal muscle disease in horses that, until recently, was of unknown origin. Recent research (2013-14) showed SPM to be caused by the toxin hypoglycin A, contained in tree seeds (fruit) including that of the sycamore.

“SPM is a disease that is extremely distressing for both the animal and the owner of the horse affected,” said BVA President Sean Wensley, BVSc, MSc, MRCVS. “BVA is working closely with our colleagues in BEVA, who deal with the aftermath of sycamore poisoning in horses all too often throughout the autumn, to ensure we get timely advice to owners to prevent their animals suffering in this way.”

High winds during the autumn of 2014 resulted in considerable contamination of pastures with sycamore seeds. Data from the National Equine Health Survey showed owners reported a four-fold increase in cases last year