Dozens of horses die after eating sycamore seeds

An outbreak of equine atypical myopathy caused by horses eating sycamore seeds has claimed the lives of more than 30 animals across Ireland.

Horse owners are being warned of a surge in cases of the potentially fatal disease linked to horses ingesting the toxin hypoglycin found in sycamore seeds, which are informally known as ‘helicopters’.

Co Down vet Hugh Suffern of Tullyraine Equine Clinic told The Irish Times he has treated 14 horses for atypical myopathy over the last three weeks. Eight of the horses died.

“As of this morning I’ve dealt with 14 cases of which eight have died and one is in the half way house at the minute,” he said. “It’s not something we have seen before. “It has been very rare and sporadic across Ireland until now.” The equine vet says the disease is normally seen in England, Belgium and the US. He is linking the recent good weather to the outbreak.

“We have had a lovely late autumn and a lot of horses are still in fields where sycamore trees have shed their leaves and seeds.

“There may also be a higher concentration of the poison in the seeds.” The signs of equine atypical myopathy include: sudden, unexplained onset of muscle stiffness, weakness, rapid heart rate, laboured breathing, sweating, blood in urine, and horses lying down unable to get up again.

Symptoms generally present for 12 to 72 hours and it is often initially diagnosed as colic. The Department of Agriculture said it is alerting vets and horse owners to a number of fatal cases of equine atypical myopathy diagnosed in recent weeks, specifically in Athlone RVL.

It is advising horse owners to take preventative measures including: * Avoid over grazing of pastures. * Feed additional forage eg hay in overgrazed pasture. * Limit turnout to less than 12 hours per day during autumn and early spring. * If feasible, remove the horses from pastures where sycamore or other maple trees are growing during the risk period.

A statement from the department said: “Atypical myopathy is a frequently fatal muscle disease of horses, thought to be caused by the ingestion of hypoglycin A, a toxin contained in seeds from the sycamore and related trees from the maple family.

“The clinical signs include depression, sudden onset of muscle stiffness, colic-like clinical signs and dark-coloured urine.

“Young horses and those new to an affected pasture appear to be at greatest risk, especially where grass is short or scarce.

“The risk period is likely to be greatest when fresh seeds are on the ground, which is in the autumn and winter.

“However the risk may remain for as long as significant numbers of sycamore seeds remain intact and edible on the ground; horse owners are advised to exercise their judgement on this.”