Question: are sycamore seeds poisonous to horses?
Answer: Atypical Myopathy “Sycamore Poisoning” in Horses. Atypical myopathy (“Sycamore poisoning”) is a frequently fatal disease of horses caused by eating Sycamore seeds (“helicopters”) or seedlings. The disease results in muscle damage and particularly affects the muscles that enable the horse to stand and breathe.