The EPSM/PSSM group is for anyone who owns a horse with EPSM/PSSM or suspects their horse may have this condition.

Polysaccharide Storage Myopathy (PSSM), also referred to as Equine Polysaccharide Storage Myopathy (EPSM), is a common form of tying-up in many horse breeds and is characterized by excessive and abnormal storage of sugar (polysaccharide) in muscle cells.

Horses showing these signs:

• Muscle stiffness, cramping or pain
• Muscle fasciculation (twitching, quivering or spasm)
• Exercise intolerance
• Firm (hard) muscles, especially in the hindquarters
• Lameness, stiff choppy gaits, tripping
• Discolored brown urine (myoglobinuria)
• Progressive weakness
• Difficulty backing up, reluctant to pick up hind legs

may have EPSM/PSSM, which can be confirmed by diagnostic testing through the University of Minnesota Neuromuscular Diagnostic Laboratory.

As more is learned about these neuromuscular conditions, new approaches for managing EPSM/PSSM (and RER or Recurrent Exertional Rhabdomyolysis) through nutrition and training are emerging. Combined with the experience of list members here, you can learn how to apply these approaches to your situation – and regain your equine partner.

New members will have their initial posts moderated to prevent spam and inappropriate material. Advertising, solicitation by private email and selling products or services are not permitted. Please contact the group moderators if you have any question about these policies.

The EPSM group would like to express their thanks to Barbara Harmon at for allowing us to use the image "Equine horse muscle structure by BH Visualart, www.bhvisualart.com"