British horse owners are being warned to keep an eye out for sycamore trees in or near pastures, as the danger period for Seasonal Pasture Myopathy (SPM) looms.
Sycamore seeds are toxic and can cause the fatal disease Atypical Myopathy (AM) or, as it is now correctly termed, Seasonal Pasture Myopathy. While trees are in full leaf and the seeds clearly visible at this time of year it should be easier to identify them and take steps to minimise the risk of horses eating them, the British Equine Veterinary Association (BEVA) says.
SPM is a highly fatal muscle disease in horses that, until recently, was of unknown origin. Research in 2013-14 showed it to be caused by the toxin hypoglycin A contained in tree seeds, including that of the sycamore. High winds during last autumn resulted in considerable contamination of pastures with sycamore seeds and saw veterinary practices across the UK managing large numbers of horses with this condition. Data from the National Equine Health Survey showed a four-fold increase in cases last year.
Horses that develop SPM are usually kept in sparse pastures with an accumulation of dead leaves, dead wood and trees in or around the pasture and are often not fed any supplementary hay or feed. While the seeds may not be directly palatable, horses grazing on poor quality pasture may ingest considerable numbers of them.
Horse owners are advised to identify sycamore trees on or near grazing land and take steps before the autumn to prevent the seeds falling where they are in reach of horses.
- Restrict access to seeds by using temporary fencing.
- Ensure horses have access to good quality uncontaminated pasture.
- Move horses off pasture at times of risk.
- Provide supplementary feed in the field to minimise the risk of horses being tempted to ingest seeds.
- Avoid leaving wet hay on the ground where it will rot.
- Discuss the risks and how to identify early clinical signs of AM with your veterinary surgeon.
- Being aware that a field without sycamore trees can still contain seeds spread by high winds or flood water.
BEVA president elect Mark Bowen said preparation was key. “We are urging horse owners to be prepared in 2015 to try to reduce the impact of this devastating condition.
“We would urge horse owners to resist the natural urge to fell trees, since doing so can lead to massive pasture contamination further increasing the risks to their horses.”