PRRS Intervention Study

Initial findings of a project examining different intervention strategies for porcine reproductive respiratory syndrome (PRRS) show that no intervention leads to the worst outcomes, Dr Zvonimir Poljak told delegates at the 28th Centralia Swine Research Update at the University of Guelph on 28 January 2009.

30 April 2009

3 minute read

Dr Zvonimir Poljak, Ontario Veterinary College (OVC), in cooperation with the Ontario Pork Industry Council Swine Health Advisory Board (OSHAB), has carried out a project to assess production and economic outcomes from intervention strategies typically used in porcine reproductive respiratory syndrome (PRRS) outbreaks in Canadian sow herds.

Swine veterinarians in Ontario and Quebec were contacted and asked to provide computer records from sow herds that experienced PRRS outbreaks between 2004 and 2008. Currently, 60 per cent of the data is from Quebec and 40 per cent from Ontario.

Production parameters were determined:

during the outbreak
six months before the outbreak, and
six months after the outbreak.

For each herd, the average number of pigs weaned per week during the outbreak and six months after the outbreak were compared with production during the six months before the outbreak.

To date, 25 outbreaks have been analysed, with the following distribution in each category:

no intervention (28 per cent)
early homologous (serum therapy) exposure (4 per cent)
late homologous exposure (20 per cent)
homologous exposure and tilmicosin (12 per cent)
tilmicosin alone (28 per cent)
vaccination with commercial vaccine (8 per cent)

The average duration of an outbreak was shortest (10 weeks) in the late homologous exposure group and longest (22 weeks) in the commercial vaccination group. The 'no intervention' strategy yielded the most dramatic production and economic losses – the decrease in the number of pigs weaned per week during an outbreak was proportionally largest, and average production during the six months after the outbreak was declared over was lowest, in the 'no intervention' strategy group. However, because the estimates were based on a very small number of herds in each intervention category, the results need to be interpreted with caution.

The project is continuing throughout 2009 and data from new outbreaks will be added in order to provide better information to the industry.

This summary was written Janet Alsop, veterinarian for Disease Prevention-Swine of OMAFRA.