Atypical Myopathy – Is Your Tree Poisonous ?
It is very important that you can reliably identify Sycamore trees that are either in or surround your field. Not knowing if a tree is a Sycamore could result in the death of your horse. They can be identified by their leaves, the saplings and the helicopter seeds, all of which can be poisonous to horses.
Even if you don’t see a Sycamore in or close to your field does not mean your horses are not at risk. Sycamore seeds (helicopters) can blow in the wind for many hundreds of metres and germinate as saplings in the Spring.
Just because horses have grazed in a field with Sycamore for years and no horse has ever died does not mean your horse will not succumb to the disease and die. This has happened many times. We do not know enough about the disease to be 100% certain your horse will not react to the poison in the trees, their leaves, seeds and saplings. You can however get your trees tested to be 100% sure if they contain the Hypoglycin A (HGA) toxin fatal to some horses.
To test if your tree or trees have traces of HGA in them you can send a sample of the leaves and seeds to the Royal Veterinary College who will carry out the necessary testing. You can find out more specific detail here.
What is important to appreciate is that not all trees will have the same level of toxin, it is also possible that the level of toxin will vary in different parts of the tree and from year to year. It is only a “safe tree” so to speak if no levels of HGA are found at all.
It is also important to note that currently there is no evidence to outline how much of the toxin a horse needs to eat in order to become sick. There is a school of thought that it is more likely to affect young horses and old horses but as so little research has been done it is best to not allow horses of any age to graze areas of land where Sycamore trees are present. It is also suggested that limiting grazing to a maximum of 6 hours only may be a way to reduce the likelihood of the horse becoming affected.
The image below shows the Sycamore Tree that is highly toxic, not to be confused with the Norwegian Maple or Field Maple which are non toxic.
