Atypical myopathy: sycamore seeds linked to horse deaths

Vets are warning that a newly recognised disease is posing a serious risk to horses.

13th November 2014
@Thinkstock - Atypical myopathy Sycamore seeds poison horses

Vets are warning that a newly recognised disease is posing a serious risk to horses. Sycamore seed poisoning, or atypical myopathy, is being increasingly blamed for sudden horse deaths, with an unusually high number of cases reported this autumn. 

The distinctive helicopter-like sycamore seeds contain the toxin Hypoglycin A, which can be poisonous to horses when ingested. Affected animals typically show signs of discomfort, sweating and instability. The poison is rapidly progressive and particularly affects stomach and cardiac muscles, and can lead to death within hours.

Whilst sycamore poinoning presents similar symtoms to colic, autopsies can prove atypical myopathy if toxins and a buildup of fatty acids in muscles are found. Sycamore poisoning is dissimilar to ragwort poisoning, which affects the liver. 

Equine veterinary expert Gil Riley told

"Atypical myopathy can present similar symptoms to colic, and in both cases horses will breath rapidly, present abdominal pain and want to lie down. However, a blood test and urine test can quickly prove atypical myopathy. Whilst the death rate is high, at around 80% horses can recover if they are quicky given sterile fluids and put on a drip to help flush toxins from their bodies. 

There's a lot we don't know about sycamore poisoning, but we've suspected for years that this could be the cause of unusual colics and unexplained sudden deaths in horses."

Riley also gave preventative advice to horse owners, advising that sycamore trees and their surrounding area should be fenced off, as the seeds can travel far. He recommended that seeds on grazing land be removed, and that extra feed be provided so that horses weren't left hungry enough to eat the seeds. 

A Defra spokesperson said: “Atypical myopathy, is caused by a poisonous substance and is not infectious. We encourage all livestock owners, particularly those with horses, to be aware of the risks that sycamore poses to their animals.” 

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