PSSM is a muscle disorder in horses with Quarter Horse, Paint, Appaloosa, Warmblood and Draft bloodlines. Clinical signs vary but include muscle soreness, atrophy, weakness, reluctance to use the hind quarters, episodes of “tying-up”, muscle tremor, stiffness and hard/firm muscles. For more extensive information, please refer to the
Michidan State University Neuromuscular Diagnostic Laboratory.