title: Encephalopathy with idiopathic hyperammonaemia and Alzheimer type II astrocytes in equidae.
abstract: In 3 mature female horses of varying breeds, episodes of colic and depression for 14 days preceded an encephalopathic disorder with maniacal behaviour, anxiety, profuse sweating and, in one case, terminal opisthotonus. Blood ammonia levels were elevated approximately 10-fold. At necropsy, there were gastrointestinal serosal and mesenteric haemorrhages. Histologically, all 3 cases revealed diffuse Alzheimer type II astrocytes in the cerebral grey matter. Alzheimer type II astrocytes were glial fibrillary acidic protein (GFAP) negative or only weakly positive, weakly S-100 positive, and vimentin negative. In the absence of primary hepatic and/or renal lesions, an increase in intestinal ammonia absorption due to ileus or increased ammonia production by colonic bacteria is hypothesised.
authors.affiliation: Department of Pathology, New York State College of Veterinary Medicine, Cornell University, Ithaca 14850, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Hasel
authors.forename: B A
authors.initials: BA
authors.lastname: Summers
authors.forename: A
authors.initials: A
authors.lastname: De Lahunta
mesh_terms: D000544:Alzheimer Disease / Q000473:pathology / Q000662:veterinary*; D000641:Ammonia / Q000097:blood*; D000818:Animals; D001253:Astrocytes / Q000473:pathology*; D001928:Brain Diseases, Metabolic / Q000473:pathology / Q000662:veterinary*; D017809:Fatal Outcome; D005260:Female; D006734:Horse Diseases / Q000473:pathology*; D006736:Horses; D007150:Immunohistochemistry; D007668:Kidney / Q000473:pathology; D008099:Liver / Q000473:pathology; D013577:Syndrome
chemical_list: D000641:Ammonia