Hypoglycin A, the toxic amino acid that causes atypical myopathy, is found in certain sycamore and box elder tree seeds. | Photo: Franz Xaver/Wikimedia Commons

Think atypical myopathy—an often-deadly muscle disease of British and European horses caused by a toxin found in sycamore seeds—only affects grazing horses that eat the seeds by mistake? Think again. Researchers recently published a study describing what they believe to be the first reported case of a newborn foal in the Czech Republic dying due to atypical myopathy complications.

“It was surprising for the owner as well as for the veterinarian, but atypical myopathy was confirmed by elevated creatinine kinase (CK) activity,” said Petr Jahn, PhD, of the University of Veterinary and Pharmaceutical Sciences Faculty of Veterinary Medicine’s Equine Clinic, in Brno, Czech Republic.

The Haflinger foal was born in spring to a mare that had fallen ill the previous autumn after consuming sycamore tree (Acer pseudoplatanus) seeds containing the causative toxin, hypoglycin A. The mare was six months pregnant at the time and made a full recovery, Jahn said. Around 75% of affected horses die from the disease