In the past two weeks I’ve been involved in working with producers, veterinarians and allied industry on a number of filtered sow unit issues. In addition, I’ve spoken with a large number of people on the issue of filtered air for sow units and program planning for future conferences with filtration on the agenda.

Much of the discussion, especially for those without direct experience in filtration systems, has involved clarification of what filtration involves and how to assess whether the expense is justified. As the popular press has reported, many sow units in southern Minnesota and northern Iowa have invested in air filtration systems as part of their PRRS risk strategies.

Note that I said filtration is part of risk strategy. The mistake many have made is to think of air filtration as a PRRS prevention solution. Filtration is only 1 tool in the process of reducing the risk of breaking with PRRS. The addition of 100% air filtration to a sow unit will not prevent PRRS from getting into the unit.

Filtration will prevent PRRS from getting into the unit from air that enters the unit coming thru the filters. It won’t keep out PRRS that comes in from air leaks or biosecurity failures such as employee disregard for biosecurity protocols, wet and contaminated packages, etc.

The important message for those of you who may be considering air filtration for a sow unit is that filtration is only 1 tool in a risk reduction strategy. It won’t prevent PRRS by itself.

If you are considering filtration, the first step is to do a PRRS risk assessment – what are you risks of getting the virus into the unit from a variety of directions. If having PRRS contaminated finishers nearby or having a higher risk of airborne introduction of the virus is identified, then think about filtration as a means to reduce the risk. At the same time, if you don’t reduce the risk from all of the other identified risk factors, don’t invest in filtration as you haven’t done a good job of reducing the overall risk to the sow unit.