A “surge of cases” of the deadly disease equine atypical myopathy (EAM) has been reported across England in the past few days.
High mortality rate
EAM affects horses who have ingested seeds from sycamore trees, and the condition carries a 70% mortality rate.
Paton and Lee equine veterinary surgery in Witham, Essex confirmed its first case of EAM last week (15 October), while Rossdales Equine Hospital in Newmarket diagnosed five cases within 36 hours.
The Royal Veterinary College (RVC), who has also seen five cases of EAM in the past few days, recommends horse owners restrict access to sycamore trees.
Restrict access
“Avoid letting horses graze pastures that are contaminated with sycamore seeds or rake up and remove the seeds where possible,” a spokesperson from RVC said.
“Where sycamore trees are unavoidably present, adequate supplementary feed should be provided but care must be taken not to allow hay to became wet and rot.”
The disease has been recognised for a number of years, but the cause was only identified last year following a study published in the Equine Veterinary Journal. It found that EAM is triggered by eating sycamore seeds and seedlings, which contain a toxin called Hypoglycin-A.
Weather changes
Cases often follow a sudden changes in weather conditions, such as heavy rain or high winds, which spread the seeds. Therefore a field without a sycamore tree can still contain the distinctive seeds.
According to the RVC prompt diagnosis and treatment is essential if the affected horse is to have any chance of survival.
The key sign of EAM is the sudden onset of muscle weakness or stiffness. If undiagnosed the horse may be found collapsed, or even dead. Other signs include laboured breathing, colic-like symptoms and dark red-brown urine.
‘Devastated’
One Essex owner posted on Facebook they were “devastated” by the loss of their horse Oliver to the disease. Just 12 hours prior to his death he had been ridden and he was “healthy and happy”, but by the following morning he had passed away.
His field mate is receiving around the clock care by House and Jackson practice. Vet Erik Belloy told H&C they have dealt with around five cases of EAM. Two horses have died, one has made a full recovery and the other two are doing “reasonably well”.
Erik advised horse owners to be “particularly vigilant” at this time of year, and also in the spring.
“Atypical myopathy is quite common this time of year, as seeds fall off the trees which contain the toxins,” he said. “It is also associated with sudden wet weather, this could be because the toxins get out of seeds and onto fields. There is lots of research being carried out right now, but not one can tell for you for sure.”