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Home:Equine Diseases: Equine Myopathy

Equine Diseases


Equine Myopathy is the term given to damaged muscle fibres. There are many reasons why muscle fibres will fail to function correctly, but all result in muscle weakness, stiffness and cramps.  The name myopathy is a general name given to any disease that originates in the muscle fibres. There are various types of myopathies in different species, but namely where equine diseases are concerned, there are two main types still undergoing research.  These are PSSM – Polysaccharide storage myopathy and Exertional myopathy. 




  • Cramping of muscles
  • Muscle spasms
  • Stiffening
  • Muscle weakness 

The two main types of equine myopathies to be considered are:
- Exertional Myopathy: This is more commonly known as ‘Tying up’ and is a common cause of mal performance in horses. The severity of this form of equine myopathy can vary from mild to severe muscle cramping, causing damage in the muscle.
An excess of carbohydrate in the equine diet can cause “tying up” or this exertional myopathy, as can a diet that is low in Vitamin E and selenium.  The obvious causes of equine myopathy from this type of diet can be seen in the behaviour of the horse.  For example, the horse will show a reluctance to move, exhaustion, a quickened heart rate, dehydration and even collapse.
Treatment can significantly reduce equine myopathy disease by implementing a proper exercise and nutrition program.

- PSSM Myopathy:  ‘Polysaccharide storage myopathy’ is a serious equine disease with little hope of recovery.  To date it remains incurable.  It varies drastically in different breeds of horse.  Thoroughbreds seem to be the least affected. It is an area of research that is still undergoing study but so far it has been established that the overproduction of glycogen is considered to be the underlying cause of this form of equine myopathy.




  • Physical Therapy
  • Drug Treatment
  • Surgery
  • Acupuncture

These various treatments have been suggested for the treatment of many different types of myopathy.