Answer

By Your Horse

Nutritionist Katie Williams says:

Muscle problems that have previously been referred to as tying up or azoturia are now grouped under the name Equine Rhabdomyolysis Syndrome (ERS). This can be divided into problems that are sporadic or chronic.
The chronic group can be further divided into two distinct problems, each with a different cause. The first is known as Recurrent Equine Rhabdomyolysis (RER) and is related to a genetic defect in the regulation of calcium cells. The other, Polysaccharide Storage Myopathy (PSSM) is caused by abnormal levels of glycogen building up in muscle cells.
There are a number of trigger factors that have been reported to result in sporadic cases of ERS. These include high starch diets, feeding when not exercising, over excitability, electrolyte losses through excessive sweating and even viral infections.
To try to reduce the chances of another episode, it’s important to keep your horse’s starch and sugar intake as low as possible.