Detecting subpopulations after PRRS virus infection in large breeding herds using multiple serologic tests

SAD: Swine Health Center, 621 Pacific Avenue, Morris, Minnesota, 56267; HSJ, BKP, TM, CP: Clinical and Population Sciences, 1988 Fitch Avenue, Room 225, University of Minnesota, St. Paul, Minnesota, 55108; SH, LT: Abilene Animal Hospital, 320 Northeast 14th Street, Abilene, Kansas 67410 ince its inception, nursery depopulation (ND) as a potential method for controlling postweaning porcine reproductive and respiratory syndrome (PRRS) has met with both success and failure.1 While the majority of the farms that have used ND reported improvements in nursery performance, in certain cases postweaning PRRS problems have persisted due to the inability to control transmission of virus in the breeding herd.2 While the use of commercially available PRRS vaccines has frequently improved weaned piglet performance, in some cases problems have persisted. Therefore, it appears that preventing the transmission of PRRS virus among adult swine is important to the success of both ND and vaccination regimes, and it becomes critical to determine the factors that predispose viral shedding within the breeding herd.