Prevention of the spread of porcine reproductive and respiratory syndrome virus in endemically infected pig herds by nursery depopulation
Dee, S.A.; Joo, H.S.
Veterinary Record 135(1): 6-9
1994
ISSN/ISBN: 0042-4900 PMID: 7985341 Document Number: 432497
An attempt was made to prevent the spread of the virus of porcine reproductive and respiratory syndrome (PRRS) on 3 Minnesota pig farms with a history of chronic nursing pig problems, including poor growth rates and increased mortality of post weaning pigs. The PRRS virus and different bacterial pathogens were isolated from all 3 farms during the initial investigation, and all the farms had a high prevalence of PRRS virus-seronegative breeding animals. All the pigs tested within one week after weaning when they were 18 to 22 weeks old, were seronegative, whereas 80 to 100% of the pigs tested at 8 to 9 weeks had antibody titres ranging from 1:64 to 1:1024 by an indirect fluorescent antibody test. The seroprevalence among the finishing pigs on the 3 farms ranged from 25 to 50%. An eradication protocol was established on each farm, involving emptying the nurseries, followed by pumping out the slurry pits and cleaning, washing and disinfecting 3 times in 14 days. After the nurseries were repopulated there were improvements in nursery mortality and average daily weight gain, and no seropositive animals were detected in the nurseries on any of the farms; the seronegative status was maintained for the 6-month testing period.