Blue Cross is urging horse owners to keep their horses away from sycamore trees after a rise in cases of atypical myopathy (AM).

One of the charity’s ponies is thought to have died from AM, an often fatal muscle disease. It is thought to be caused by the ingestion of hypoglycin A, a toxin found in seeds from sycamores.

British vets have seen a rise in AM over the spring, with 12 new cases announced in the last pro weeks in Hampshire, six of which were fatal.

Symptoms of AM include depression, muscle weakness, recumbency and dark red urine. Young horses appear to be more susceptible, along with horses grazing on parched land.

Natasha Seely, of Bourton Vale Equine Clinic in Gloucestershire, said: “Horse owners need to be alert at all times, but especially during the spring and autumn. 

“If they are worried their horse may be showing any symptoms they must call their vet immediately.”

Gemma Taylor, education officer at Blue Cross, added: “One of our horses in an experienced loan home unfortunately lost his battle with this fatal disease last week. Although his field did not have any sycamore trees nearby it is thought he had ingested seeds brought in by floodwater.

“This tragic incident has bought home how horrific this disease can be and how all horse owners have to stay alert to the dangers to try to minimise this dreadful disease.”

The Blue Cross advises checking horses twice a day, feeding forage such as hay in parched fields and removing young sampling plants.

For more information, visit

View your activity >

Leave a Reply

Be the First to Comment!

Notify of