Risk factors associated with endemic reproductive deficiencies caused by PRRSV infection
Angela K. Baysinger, DVM, MS; Cate E. Dewey, DVM, PhD; Barbara E. Straw, DVM, PhD; Michael C. Brumm, PhD; Jack Schmitz, DVM, PhD; Alan Doster, DVM, PhD; Clayton Kelling, DVM, -PhD
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Objective: To describe chronic reproductive losses and determineassociated risk factors in swine herds positive for porcine reproductiveand respiratory syndrome virus (PRRSV) in the midwestern United -States.
Methods: Twenty-seven PRRSV-positive breeding herds were monitoredfor 6 months before and 1 year after the PRRSV outbreak. Herds were statisticallyanalyzed and assigned to one of two herd PRRSV statuses: either "recovered"if measured reproductive parameters returned to pre-outbreak levels, or"chronic" if > 2 reproductive parameters did not return toat least 90% of pre-outbreak levels. Data regarding herd attributes andmanagement practices prevailing in the herds were collected via a producersurvey. Multifactorial logistic regression analysis was applied to determineassociations between management practices or herd attributes and the PRRSVstatus of the -herd.
Results: Seven of 27 herds (26%) were categorized as chronic PRRSV-positivebreeding herds, while the other 20 were categorized as "recovered."Two logistic models were produced for the chronic herds: one containingmanagement factors statistically associated with a chronic PRRSV status(raising own replacement gilts, isolation of new breeding stock, numberof sows per farrowing room, and inventory of growing pigs), and one identifyingherd attributes (parity and sow inventory) that were associated with a chronicPRRSV -status.
Implications: PRRSV-positive herds can have chronic reproductivelosses in which some reproductive parameters will not return to 90% of prediagnosislevels. Certain herd attribute/management factors are associated with increasedor decreased risk.