A retrospective study of factors associated with eliminating circulating pseudorabies virus in sow herds

John Deen, DVM, PhD, Dipl ABVP-SHM; Gene A. Erickson, DVM; Gail Scherba, DVM, PhD

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Objective: To define risk factors associated with sowherds that have not been successful in stopping circulation ofpseudorabies virus (PRV, Aujeszky's disease).

Methods: Officials in charge of eradicating PRV in themajor swine-producing states in the United States completed surveysto compare herds in which virus circulation had been successfullystopped (cases) to those in which it was not (controls) in anunmatched case-control design. Unsuccessful herds were definedas breeding herds that were diagnosed with PRV but that continuedto have replacement animals become infected. The diagnostic andvaccination methods, characteristics of the farm and livestock,and eradication methods attempted were investigated. Multiplelogistic regression analysis was used to compare and select statisticallysignificant variables.

Results: Offsite and all-in-all-out (AIAO) finishingwas more frequent among successful than unsuccessful herds. Thefrequency of other practices, such as sorting back pigs from oneAIAO group to another, did not differ between successful and unsuccessfulherds. In a higher proportion of successful herds, sows were culleddirectly from the farrowing room and conversely, a lower proportionof successful herds mixed cull sows with the finishing pigs. Unsuccessfulherds were more likely to have other infected herds within 3.2km (2 miles). Unsuccessful farms were more likely to raise giltsin their own facilities and did not cull out of the farrowingroom but instead retained the sows. They also did not regularlyclean and disinfect the livestock trucks or use a syringe dedicatedto PRV vaccinations.

Implications: The picture of the problem herd that developsfrom this analysis is of a herd that is slow to take up new technologies,particularly biosecurity and disease control technologies.

Keywords: pseudorabies virus, Aujeszky's disease virus, eradication

RIS citationCite as: Deen J, Erickson GA, Scherba G. A retrospective study of factors associated with eliminating circulating pseudorabies virus in sow herds. J Swine Health Prod 1999;7(4):147-150.

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