The present invention include a method of protecting an animal against Lawsonia intracellularis infections, the method including administering a dose of live virulent L. intracellularis to the animal, allowing a subclinical L. intracellularis infection to develop in the animal, and administering one or more antibiotics to the animal, wherein the one or more antibiotic is administered in a dose sufficient to abbreviate the subclinical L. intracellularis infection.
