All across the Midwest, we are starting to experience the changing of the seasons. Weather is changing, kids are heading back to school, and combines are being prepared for the impending harvest. For many swine producers, unfortunately, it is also a time of year which conjures up thoughts of PRRS virus. Porcine Respiratory and Reproductive Syndrome (PRRS) virus is a virus that affects swine, causing significant health and financial challenges to the swine industry. The virus has a reputation of infecting swine herds across the country more frequently during the fall/winter/spring historically, although the virus can infect pigs at any time of year and should always be a concern for your herd.
As producers and veterinarians, we face the challenge daily of attempting to improve our efforts at combating this challenging disease. For Pipestone System, and as an industry, we have become better every year as we look at our rate of new infections in Pipestone System sow farms, as well as infections across a large number of herds in the United States monitored through the late Dr. Bob Morrison’s Swine Health Monitoring Project. This is evidence that the research generated and efforts put forth towards combating this disease are driving progress.
As we look in the toolbox for PRRS control, one tool that has proven effective for aiding our control efforts has been modified live PRRS vaccine. Modified live PRRS vaccine has two primary benefits and warrant strong consideration for your operation. The first of these benefits is seen in growing pig performance. In a controlled research study in which pigs were challenged with a virulent strain of PRRS virus, pigs that were previously vaccinated with PRRS vaccine significantly outperformed the pigs that were not vaccine with PRRS vaccine in wean-to-market average daily gain, and having less pigs that needed to be sold as culls at the end of the group. This economic return for vaccination was $4.35 in this study over non-vaccinated pigs.
The second benefit comes from controlling viral spread in a neighborhood. PRRS virus has been shown to travel via aerosol spread, and often can infect multiple sites in a geographical region when present. One way to help reduce the number of herds that become infected is to reduce the time and degree to which this virus is shed from infected populations. This strategy is used in pig dense areas and areas in which sows are present to decrease viral density in an area. In another controlled trial, is was demonstrated that when challenged with a virulent field strain of PRRS, pigs that were vaccinated with a modified live PRRS vaccine shed significantly less virus from the infected facility. Air samples were collected daily from this facility after pigs were challenged and only 5 days with positive air samples were detected outside of the room with vaccinated pigs, compared to 27 days with positive air samples in the non-vaccinated pigs. Additionally, PRRS virus was only detected in the air out to day 6 post-challenge in the vaccinated group, compared to day 55 in the non-vaccinated group. This shows that PRRS vaccine is a beneficial tool to help reduce the amount of virus that is shed from infected barns and reduce the challenge to nearby barns, helping protect your neighborhood.
As we approach this time of year, it is a good time to evaluate our strategies going into historical “PRRS season.” All of the tools in our PRRS control toolbox, including good biosecurity practices, air filtration, and regional and herd control strategies are all important and cannot be forgotten. PRRS vaccine is just another tool that helps us in our efforts to combat this disease. Modified live PRRS vaccine can be beneficial in improve the health and performance of the growing pig, and control viral presence within regions. Additionally, in an era where pressure is applied on antimicrobial use in livestock operations, we must evaluate our production practices and health control strategies constantly. PRRS virus infections warrant the need for antimicrobial use within infected populations and is one more reason to put forth our best efforts to prevent infection or control disease. We must use all the tools in our toolbox to help control this disease and PRRS vaccine is one of these tools that can help protect your herds.
For any questions or concerns regarding this topic please do not hesitate to contact our Pipestone team of veterinarians and swine specialists at 507-562-PIGS.
Adam Schelkopf, DVM
Pipestone Veterinary Services