title: Polysaccharide storage myopathy in Morgan, Arabian, and Standardbred related horses and Welsh-cross ponies.
abstract: Polysaccharide storage myopathy is an equine neuromuscular disorder characterized by accumulation of glycogen-related polysaccharide inclusions within skeletal muscle fibers. The pathologic criteria for diagnosis of this disorder are somewhat controversial; however, periodic acid-Schiff-positive, amylase-resistant inclusions are considered pathognomonic. Although these inclusions are most often found in affected horses related to the Quarter Horse, draft horse, and Warmblood breeds, this report describes these characteristic inclusions in muscle of five horses from nonrelated breeds (two Morgans, one Arabian, one Arabian x Thoroughbred, and one Standardbred) and two Welsh cross ponies. Affected horses had histories of recurrent exertional rhabdomyolysis, and one developed progressive weakness leading to increased recumbency. The affected ponies were part of an unrelated research project and had no apparent clinical signs.
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis 97331, USA. beth.valentine@orst.edu
authors.forename: B A
authors.initials: BA
authors.lastname: Valentine
authors.forename: S P
authors.initials: SP
authors.lastname: McDonough
authors.forename: Y F
authors.initials: YF
authors.lastname: Chang
authors.forename: A J
authors.initials: AJ
authors.lastname: Vonderchek
mesh_terms: D000681:Amylases / Q000737:chemistry; D000818:Animals; D001947:Breeding; D002239:Carbohydrate Metabolism, Inborn Errors / Q000235:genetics / Q000473:pathology / Q000662:veterinary*; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis / Q000235:genetics / Q000473:pathology*; D006736:Horses; D007150:Immunohistochemistry; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology*; D009135:Muscular Diseases / Q000235:genetics / Q000473:pathology / Q000662:veterinary*; D010503:Periodic Acid-Schiff Reaction / Q000662:veterinary; D011134:Polysaccharides / Q000032:analysis / Q000378:metabolism*; D012206:Rhabdomyolysis / Q000662:veterinary
chemical_list: D011134:Polysaccharides; D000681:Amylases