EPSM (Equine Polysaccharide Storage Myopathy) page 3

Tying Up—or Not?

Like tying up, EPSM is an “exertional rhabdomyolysis,” with a metabolic basis. In Reno’s case, EPSM proved difficult to diagnose

Over a three-year period, veterinarians couldn’t explain what was wrong with Reno. Wolfe consulted several practitioners and clinics, trying to discover the reason for his soreness and resistance to training.

Wolfe noticed atrophy in his muscles, weakening and softening. “If I pressed on his back or hindquarters with minimal pressure, I could drop him to the floor. When under saddle, he would always give way in his hind end in every transition and the canter.”

Veterinarians used imaging methods of nuclear scintigraphy (bone scan) and x-rays, looking for musculoskeletal abnormalties. They ruled out disorders like Wobblers syndrome, Lyme disease, or arthritic changes.

“I and the vets had never seen a horse get so sore,” said Wolfe. “He seemed only better if he was on Robaxin, a muscle relaxer.”

She also tried chiropractic and acupuncture. By 2001, the medical opinion was EPM, and so in 2001-2002 Reno was on the Marquis treatment regime. But he still wasn’t able to perform.

EPSM wasn’t considered likely—a disorder linked with draft breeds and Quarter Horses. Yet Valentine’s experiences have shown horses of many breeds.

She explained, “The main reason we are diagnosing more EPSM horses nowadays is because we finally know what to look for, both in the clinical problems and in the muscle itself.”