2017 is going so quick I can't believe we're in Autumn already! Atypical Myopathy (sycamore poisoning) is a disease close to my heart as my horse Clover had the disease in 2012 so it's important to me that all our clients understand the disease and what they can do to prevent it, I don't want anyone to have to experience it for themselves.

Atypical myopathy is a severe muscle disease that is caused by a toxin called Hypoglycin-A found in certain sycamore seeds, leaves and seedlings. The disease is life threatening and 60 – 70% of horses with the disease will die, it is important treatment is given as soon as possible to have the best chance of survival. Any age or breed of horse can be affected although younger horses are at a higher risk.

We see the highest incidence of the disease in the Autumn months when there are high numbers of sycamore leaves and seeds on the ground, particularly after wet and windy weather. There is a smaller spike in cases of atypical myopathy again in spring when the seedlings start growing on pasture.

The early signs can be subtle and are often unnoticed or are mistaken for other illnesses:

  • General stiffness and lethargy
  • Mild colic signs or lying down a lot
  • A low head carriage
  • Dark red-brown urine

The disease affects the muscles of the body and can affect the heart or respiratory muscles leading to cardiac arrest. If left untreated kidney failure will occur due to the high levels of toxins in the blood.

Diagnosis of Atypical Myopathy is based on clinical signs and a blood test showing very high levels of muscle enzymes (higher than usually seen for other diseases). Treatment must be initiated immediately and any delay can have a significant effect on survival. High doses of intravenous fluids are administered along with antioxidants and pain killers. If horses survive the first few days of intensive care they will usually go on to make a full recovery.

It is vital owners take measures to prevent this disease. It is highly fatal and can be avoided.

There is now a test that can be done on a sample of leaves, seeds and seedlings from your pasture that will measure the amount of Hypoglycin A in the sample and therefore the risk of your horses developing Atypical Myopathy. Different sycamore trees have different levels of toxin therefore knowing what is on your pasture is very beneficial. I would strongly urge horse owners that have any sycamores on or around their horses pastures to have them tested. As we do not yet know if the amount of toxin changes during the year I recommend testing in early Autumn.

Other preventative measures include raking and removing the sycamore leaves and seeds during the autumn and pulling up the saplings in the spring. Feed extra hay in the field to reduce the likelihood of horses eating the leaves and seeds. Even better do not graze horses in fields with sycamore trees during the riskiest times of year. Regularly check your paddocks during autumn and spring as the seeds can travel many metres in windy conditions.

If you have any questions about Atypical Myopathy or the test that can be done on a sample of your sycamores then please do not hesitate to get in touch with us.