Over the past few weeks, it’s been lovely driving around and seeing all the autumnal colours. However, in Autumn the European sycamore maple (Acer pseudoplatanus) and the Box elder (Acer negundo) can cause a very painful and often fatal muscle disease in horses called Atypical Myopathy. The culprit is a toxin called hypoglycin A, which is found in the helicopter blade-like seeds that provide hours of entertainment for the kids in the Autumn. The toxin has been detected in sycamore trees in New Zealand and cases are seen occasionally. Signs include stiffness, reluctance to move, lying down, colic-like signs, dark urine, sweating, difficulty breathing and even sudden death.
How much is too much?
Unfortunately, we don’t know the answer. The concentration of toxin varies between seeds from the same tree and with season, weather conditions and other stressors… so it’s very hard to predict. To further complicate things, some horses appear more susceptible than others.
How can we keep our horses safe?
Ideally, avoid grazing paddocks that contain sycamore seeds throughout Autumn. Fencing off sycamore trees may not be sufficient as these helicopter-seeds can travel over 100 m from trees in the wind. If exposure can’t be avoided, plenty of supplementary feed should be provided so that horses are less likely to eat the seeds. Paddock vacuums and groomers can be used to collect the seeds. In the Spring, the seedlings can also be a source of toxicity and the arduous task of picking seedlings is unfortunately the most fail-proof method of avoiding toxicity as both mowing (without collection) and spraying herbicides increase the risk of exposure. Paddocks that contain sycamore material shouldn’t be used for hay or haylage as both seedlings and seeds proceeds within the grass remain toxic. There isn’t any antidote for hypoglycin A but some horses do recover with supportive care.
Be on the lookout for these seeds this Autumn and if your horse does show any signs of Atypical Myopathy call us immediately as early intervention is key.