Equine Atypical Myopathy

Equine Atypical Myopathy

Equine atypical myopathy (or Atypical Myoglobinuria) is an emerging disease in the UK and Europe that causes muscle damage. The cause of this disease is currently unknown, but there is speculation that it is linked to a toxin producing bacteria called Clostridium sordelii.
According to data from the Equine Atypical Myopathy Alert Group from Spring 2012, there were 23 new cases reported by 2nd May 2012. 18 of these were in France, 4 were in Great Britain and 1 was in New Zealand.

Risk Factors:
Although the exact cause is unknown, there have been several risk factors identified, that make a horse more susceptible to the disease. Some of these risk factors are listed below:
• Young horses, typically less than 3 years old
• Horses that are in poor body condition
• Unvaccinated and un-wormed horses
• Seasons – most cases are seen in the Spring and Autumn, following periods of heavy rain, warmth and humidity
• Low levels of Vitamin E and Selenium in a horse (important anti-oxidants) may increase the risk
• Dead leaves within the pasture, or a watercourse running through the pasture
• Previous history of aytypical myopathy on the pasture

Clinical Signs:
Most cases occur rapidly, with severe, generalised muscle weakness. Horses can be found lying on their side in the field, or found dead. The mild initial clinical signs listed below are not often seen:
• Lethargy
• Decreased appetite
• Lameness, especially of hindquarters
• Muscle tremors
• Signs of colic
• Dark coloured urine
• Dark red (congested) or purple (cyanotic) coloured gums
• Low temperature (hypothermia)

What to do if you suspect a case:
Equine Atypical myopathy has a high mortality rate, but the chances of recovery are increased with early intervention and treatment.
• Call the surgery to request a visit
• Minimal movement of the horse, as any movement will further aggravate the muscle damage.

Treatment:
There is no specific treatment available for Atypical Myopathy and current treatment is aimed at the symptoms and potential cause.
• Pain killers
• Fluids – can be given via a drip if needed
• Antibiotics – for potential Clostridium sordelli infection
• Supplement vitamin E/selenium

Prevention:
• Avoid grazing on affected pastures during Spring and Autumn, especially young horses
• Keep up to date with vaccinations and worming
• Assure your horse is in a good body condition (but not too fat)
• Remove excessive amounts of dead leaves from the pasture

Further information:
More information can be found at:
• http://www.myopathieatypique.fr/en – where alerts from the Atypical Myopathy Alert Group (AMAG) are also posted.