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Induction of gross and microscopic lesions of porcine proliferative enteritis by Lawsonia intracellularis.

OBJECTIVE
To evaluate experimental induction of porcine proliferative enteritis (PPE), using cell cultured Lawsonia intracellularis (ileal symbiont intracellularis), and to determine whether dexamethasone administration or age of the host or both affects susceptibility to L intracellularis infection.


ANIMALS
Thirty-two 3- or 7-week-old pigs.


PROCEDURES
Lawsonia intracellularis was extracted from tissue with lesions of 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 inoculated orally with 100 ml of a 10-day-old cell culture preparation of the bacterium or infective intestinal homogenates. Control pigs were inoculated with uninfected Henle cells. Pigs were observed daily for clinical signs of infection and necropsied at death or at termination of the study. Lesions in the small and large intestines were recorded.


RESULTS
Diarrhea was observed in pigs 4 to 7 days after inoculation with the pure culture agent or homogenates and lasted throughout the study period. Histologic lesions consistent with PPE were detected in pigs inoculated with pure culture. Intestinal lesions were absent in control pigs inoculated with uninfected Henle cells. Differences in lesions were not significant between treatment groups that varied in age or were receiving dexamethasone. Tissue specimens from pigs at necropsy were culture negative for Salmonella spp and Serpulina hyodysenteriae.


CONCLUSION AND CLINICAL RELEVANCE
Gross and microscopic lesions typical of acute PPE were induced in pigs by use of a cell culture agent. Age differences and the stress induced by administration of dexamethasone had no effect on development of intestinal lesions.