title: Immunohistochemical and ultrastructural detection of intestinal spirochetes in Thoroughbred horses.
abstract: Studies of equine intestinal spirochetes have long focused on intestinal contents alone, but intestinal spirochetosis has been reported recently in a 21-month-old Thoroughbred colt in Japan. To define the clinical and pathological significances of intestinal spirochetosis in several horses, an epizootiologic survey with histologic, immunohistochemical, and ultrastructural methods was conducted for Brachyspira antigen-containing intestinal spirochetes in 12 diseased or injured Thoroughbred horses, aged from 35 days to 17 years. Brachyspira antigen-containing spirochetes were found in 7 of 12 horses (58.3%) and were more frequent in the cecum than in other parts of the bowel. It was not clear whether the infection was clinically related to diarrhea or dysentery, but histopathology revealed a close association between the bacterial infection and epithelial hyperplasia. Crypt epithelium consisted mainly of goblet cells and showed frequent mitosis throughout its length. Inflammatory cells and congestion were also present. There were numerous spirochetes in the crypts, and some invaded the cecal and colonic epithelia and underlying lamina propria. Ultrastructurally, the spirochetes were divided into 4 types. Three types were identified in degenerative epithelial cells or intracellularly. Brachyspira antigen-containing intestinal spirochetes invading the mucosa were capable of causing epithelial hyperplasia in the cecum and colon in the horses. The findings in this study will increase awareness of the importance of intestinal spirochetosis and may also be helpful for diagnosis and treatment of this condition.
authors.affiliation: Hokkaido Research Station, National Institute of Animal Health, Sapporo, Hokkaido 062-0045, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Shibahara
authors.forename: Atsutoshi
authors.initials: A
authors.lastname: Kuwano
authors.forename: Takanori
authors.initials: T
authors.lastname: Ueno
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Katayama
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Ohya
authors.forename: Sadao
authors.initials: S
authors.lastname: Taharaguchi
authors.forename: Shinji
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Takashi
authors.initials: T
authors.lastname: Umemura
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: Koichi
authors.initials: K
authors.lastname: Kadota
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis; D003092:Colitis / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D004279:DNA, Viral / Q000378:metabolism; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis* / Q000382:microbiology / Q000473:pathology; D006736:Horses; D007150:Immunohistochemistry / Q000379:methods / Q000662:veterinary; D007422:Intestines / Q000382:microbiology* / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron / Q000662:veterinary; D013144:Spirochaetales / Q000276:immunology / Q000302:isolation & purification* / Q000648:ultrastructure; D013145:Spirochaetales Infections / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*
chemical_list: D000942:Antigens, Bacterial; D004279:DNA, Viral