The effect of porcine proliferative enteropathy on the introduction of gilts into recipient herds

Porcine proliferative enteropathy (PPE) caused by Lawsonia intracellularis (LI) is one of the most important enteric diseases in growing swine. The acute form of this disease, proliferative hemorrhagic enteropathy (PHE), has become a common problem when replacement breeding stock are introduced into a herd. In the cases described, animals of different immune status were moved between supply and recipient herds. An LI-free breeding-stock herd (Herd A) supplied gilts to four herds, one of which was LI-free (Herd B). During a 1-year period, PHE was observed in replacement animals after they entered the LI-infected herds (Herds C, D, and E); however, no problems were reported in Herd B. After an outbreak of PHE occurred in Herd A, replacement animals from this herd no longer developed PHE in the three LI-infected recipient herds. However, an outbreak of PHE occurred in Herd B when LI-infected replacement gilts were introduced.