Wean to Market PRRS Control Strategies

By Dr. Bryan Myers
As I begin to write this article, it is 6:00 AM and it is 38 degrees outside and I can’t see my neighbor’s house because of the fog.  Unfortunately, the first thing that comes to mind is this is a day that PRRS virus thrives in.  According to initial research done by Pipestone’s Director of Research, Dr. Scott Dee, PRRS virus can spread for at least 5.5 miles in the air under optimum conditions.  Look all four directions from your barn and think about how many other barns there are within 5.5 miles.  Although we can’t control the weather conditions, we can do some things that may help decrease the effects of a PRRS virus introduction.  The short list, (although far from being all inclusive) includes PRRS vaccination, biosecurity plans, pigflow and control of secondary diseases.

PRRS Vaccination:  Vaccinating for PRRS virus in wean to finish pigs is a key control strategy for minimizing the effects of a PRRS infection.  Although PRRS vaccine will not prevent the introduction of PRRS virus, the clinical signs and detrimental effects associated with PRRS can be diminished.  Studies have shown that PRRS vaccination will not only reduce PRRS transmission, but will improve performance through increased average daily gain and reduced culls when a group of pigs has been infected with PRRS.  PRRS vaccine is one of the best tools in the toolbox to help prevent losses associated with PRRS on a continuous flow finishing site.  Ask one of our veterinarians if PRRS vaccination is a good decision for your farm.

Biosecurity:  All areas outside of your barn should be considered contaminated.  The ground that you walked in on was also traveled on by feed trucks, gas trucks, market trucks and others too many to mention.  Having a clean-dirty line is an effective tool to prevent “walking the virus into the barn”.  Leave your outside clothes and shoes on the dirty side and change into designated barn clothes and shoes on the clean side.

Control of Secondary Diseases:  Although many diseases can cause significant issues on their own, often times when they are associated with PRRS virus the clinical effects can be much more severe.   Diseases such as Mycoplasma and Circovirus have very effective vaccines and when vaccinating for correctly clinical disease can be prevented.  Prevention of bacterial diseases is aimed at environmental control and injectable or water antibiotics as necessary.

Pigflow:  Once infected with PRRS virus, pigs can shed the virus into the environment for weeks and even months.  Pigs infected with PRRS today can shed the virus to new pigs that may arrive at your farm two months later.  Although vaccination, as discussed above will minimize the shedding, some virus may get out into the environment infecting other pigs.  Decreasing the number of age groups present on a site will improve the chance of eliminating virus from the site if infected.  Changing pigflow to get to all in – all out by site will help with PRRS control as well as controlling other disease such as Influenza.  Even if you can’t get to all in – all out by site, decreasing the number of ages on a site from three to two makes a big difference.  It may be beneficial for your operation to receive weaned pigs every 8-9 weeks instead of every 4-5 weeks.

Dr. Bryan Myers

Thirty years after PRRS virus was first diagnosed in the U.S., it continues to be the number one disease concern plaguing the swine industry.  There are no easy solutions to controlling or preventing PRRS.  Contact your Pipestone veterinarian for the best PRRS prevention strategy for your farm.