Equine Atypical Myopathy (EAM)

Equine atypical myopathy is a debilitating condition which is often fatal with a survival rate of approximately 20%. The condition results in the destruction of skeletal muscle and often the muscle of the heart and diaphragm.

Symptomes include

  • Dark coloured urine
  • Muscle stiffness/ weakness unrelated to exercise
  • Muscle tremors
  • Lethargy
  • Some cases show colic like symptoms
  • Choke like retching neck spasms
  • Frenzied vocalisation
  • Vigorous head shaking / nodding
  • Lying down unwilling to stand but eating.

The initial symptoms can progress rapidly with many cases developing difficulties in eating, breathing, heart problems and unable to stand up. If your horse is suffering from a combination of any of these symptoms please call the clinic to book an appointment.

The initial symptoms can progress rapidly with many cases developing difficulties in eating, breathing, heart problems and unable to stand up. If your horse is suffering from a combination of any of these symptoms please call the clinic to book an appointment.

Cause

The current theory for this disease is related to work carried out by researchers at the University of Minnesota identified a link between the disease and the Box Elder tree (Acer negundo), which is found in the United States. More recently it has been demonstrated that the same toxin found in the Box Elder tree (known as Hypoglycin A) is also found in the European Sycamore tree (Acer pseudoplatanus), and this is thought to be the cause of the majority of cases seen in the UK.

European Sycamore European Sycamore Fruit European Sycamore Helicopters

Humans eating unripe fruits from other members of this family also can suffer severe illness which is related to hypoglycin A.

Prevalence and risk factors

Despite not knowing the exact cause of EAM, certain factors have been identified

  • Horses out at pasture
  • Youngstock < 3 years are most at risk (although can affect adults)
  • Horses in poor condition (although can affect any horse)
  • Unwormed and unvaccinated horses
  • Bare pasture, containing a stream/river, accumulation of dead leaves
  • Mainly seen in spring and autumn
  • Sudden adverse change in weather (change in conditions from dry to damp).

Diagnosis

This is based on clinical signs and routine blood tests revealing critically elevated muscle enzymes ( CPK and AST).

Treatment

Treatment is supportive and includes intensive intravenous fluid therapy, anti-inflammatories, painkillers, multivitamins, vitamin E and is generally more successful when treated in the early stages.

Advice to help prevent atypical myopathy

  • Section off areas around sycamore trees and collect and dispose of leaves safely away from horses
  • Remove young sapling plants
  • Fence off wet areas
  • Ensure you check your horse regularly at least twice daily
  • Be vigilant of the potential signs of this disease and act quickly if your horse becomes poorly.
  • Limit turnout. Ideally stable horses over night (October- December)
  • Supply extra hay or haylage in field.

If you have any concerns please contact us for further advice. 01344 426066.

 

Scott Dunn’s Equine Clinic is part of CVS (UK) Limited, a company which owns over 300 veterinary practices in the UK. Company Registration Number 03777473. Registered Office CVS House, Owen Road, Diss, Norfolk, IP22 4ER