A RETROSPECTIVE STUDY INTO CHARACTERISTICS ASSOCIATED WITH THE SEROPREVALENCE OF PSEUDORABIES VIRUS-INFECTED BREEDING PIGS IN VACCINATED HERDS IN THE SOUTHERN NETHERLANDS

Vaccination programs to eradicate pseudorabies virus (PRV) are being c onsidered in several countries. Knowledge of factors that influence PR V transmission within vaccinated breeding herds may contribute to the success of these programs. A multivariate analysis of variance of the PRV-seroprevalence in sows in 209 herds (average seroprevalence 67.0% per herd) in the southern Netherlands revealed the following risk indi cators: (I) presence of finishing pigs; (2) production type ( producer s of finishing piglets had a higher seroprevalence than producers of b reeding stock); (3) vaccination of the sows during nursing (in compari son with vaccinating all sows simultaneously at 5 month intervals, or vaccination during the second half of gestation); (4) pig density in t he municipality where the herd was located (seroprevalence increased w ith higher pig density); (5) herd size less than 100 sows; (6) average within-herd parity (seroprevalence increased with higher within-herd parity); (7) replacement pigs raised on the premises; (8) vaccine stra in administered to the sows. Purchase policy (breeding pigs purchased between 10 weeks and 7 months of age, or use of home-bred gilts only) did not significantly contribute to the multivariate model.