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PSSM: Feed Management Provides ReliefBy Kentucky Equine Research Staff · February 8, 2010

Low-starch, high-fat feeds seem to help many horses suffering from polysaccharide storage myopathy (PSSM), a condition that causes painful muscle cramping known as tying-up. Equine diets are frequently supplemented with vegetable oil to increase the fat content and provide a safe energy source for these horses.

Scientists at the University of Minnesota experimented with using triheptanoin, a 7-carbon fat used to treat humans with glycogen storage diseases, as an alternate fat source for horses with PSSM. The test showed this fat had an unexpected detrimental effect, actually worsening exercise intolerance and causing higher levels of creatine kinase, a muscle enzyme. Dr. Stephanie Valberg of the University of Minnesota therefore suggested that long-chain fatty acids such as those in vegetable oils are better choices in the diets of PSSM horses.