Equine polysaccharide storage myopathy (EPSSM or PSSM) is a condition that causes rhabdomyolysis - also known as tying up, azoturia or set-fast - which presents as episodes of muscle stiffness and pain after exercise.
The condition is known to affect numerous breeds and types, such as warmbloods, thoroughbreds, cobs, Arabians, American Quarter Horses, Dales ponies, New Forest ponies and heavy horse breeds (see chart, below, for prevalence in various breeds). The sex of the animal is not a factor in inheriting the disease.
“Type 2 may be genetic but the exact cause is unknown”
PSSM is the abnormal accumulation of glycogen (the stored form of glucose) in muscle. There are two types of PSSM: type 1, which is caused by a known
