INDUCTION OF GROSS AND MICROSCOPIC LESIONS OF PORCINE PROLIFERATIVE ENTERITIS BY LAWSONIA-INTRACELLARIS

Objective-To evaluate experimental induction of porcine proliferative enteritis (PPE), using cell cultured Lawsonia intracellularis (ileal s ymbiont intracellularis), and to determine whether dexamethasone admin istration or age of the host or both affects susceptibility to L intra cellularis infection. Animals-Thirty-two 3- or 7-week-old pigs. Proced ures-Lawsonia intracellularis was extracted from tissue with lesions o f PPE and was subcultured in a continuous Henle 407 cell line at 37 C under an atmosphere of 5% CO2. Three-or 7-week-old pigs were inoculate d orally with 100 ml of a 10-day-old cell culture preparation of the b acterium or infective intestinal homogenates. Control pigs were inocul ated with uninfected Henle cells. Pigs were observed daily for clinica l signs of infection and necropsied at death or at termination of the study. Lesions in the small and large intestines were recorded. Result s-Diarrhea was observed in pigs 4 to 7 days after inoculation with the pure culture agent or homogenates and lasted throughout the study per iod. Histologic lesions consistent with PPE were detected in pigs inoc ulated with pure culture. intestinal lesions were absent in control pi gs inoculated with uninfected Henle cells. Differences in lesions were not significant between treatment groups that varied in age or were r eceiving dexamethasone. Tissue specimens from pigs at necropsy were cu lture negative for Salmonella spp and Serpulina hyodysenteriae. Conclu sion and Clinical Relevance-Gross and microscopic lesions typical of a cute PPE were induced in pigs by use of a cell culture agent. Age diff erences and the stress induced by administration of dexamethasone had no effect on development of intestinal lesions.