History: A 20 lb pig of unknown age had a history of diarrhea. (Thats all we know)
The ileum and distal jejunum were diffusely thickened, with a cobblestoned appearance to the serosa and corrugated mucosa which was covered in a moderate amount of green to yellow fibrin. The serosal surface of the colon had multiple focal pale grey nodules protruding from the surface.
(sorry no pictures)
Ileum: There is marked superficial necrosis of the mucosa with abundant fibrin accumulation on the mucosal surface. Crypts are multifocally dilated with neutrophils and cellular debris. Warthan-Starry silver stain was positive for intracellular curved bacteria in the apical enterocyte cytoplasm (Lawsonia intracellularis).
The mucosal epithelium is hyperplastic lined by pseudostratified columnar cells and crypts occasionally herniate into the submucosa.
The crypts are often branched and there are moderate numbers of neutrophils and macrophages in the lamina propria.
Lawsonia are intracellular bacteria that reside usually in the apical cytoplasm.
Ileum: Fibrino-necrotic ileitis, moderate, multifocal, pyogranulomatous, with mucosal hyperplasia and intracellular bacteria consistent with Lawsonia intracellularis