PSSM 1
PSSM 1 (short for polysaccharide storage myopathy) has been scientifically researched for around 15 years and refers to a hereditary glycogen storage disorder caused by a mutation of the GYS1 gene. Affected horses require grain-free, low-sugar rations rich in vitamin E, as well as optimum housing conditions, in order to remain performant.
In addition to PSSM type 1, there is also type 2 (PSSM 2). PSSM2 is currently the collective term for all horses with exertional myopathies that do not (!) show the defect of the Gys1 gene. In Germany, PSSM2 is sometimes also referred to as muscle integrity myopathy, abbreviated MIM.