Sign up now!
Don't show this again
Download the report!Continue to Site >
or wait 7 secs

Thank you for confirming your subscription!

(And remember, if ever you want to change your email preferences or unsubscribe, just click on the links at the bottom of any email.)

We’re glad you’re enjoying Pig Health Today.
Access is free but you’ll need to register to view more content.
Already registered? Sign In
Tap to download the app


Collect articles and features into your own report to read later, print or share with others

Create a New Report


Read Later

Create a new report

Report title (required) Brief description (optional)
follow us

You must be logged in to edit your profile.

Favorites Read Later My Reports PHT Special Reports
Pig Health Today is equipped with some amazing (and free) tools for organizing and sharing content, as well as creating your own magazines and special reports. To access them, please register today.
Sponsored by Zoetis

Pig Health Today | Sponsored by Zoetis


PRRSV in finishers may contribute to the disease on sow farms

Download our special report

This is one of eight reports that appears in a special edition
of Pig Health Today, “Framing the Future of PRRS.”
For a free copy, click here.


It’s time to consider the role finishing pigs play in the spread of porcine reproductive and respiratory syndrome virus (PRRSV) to sow farms, said Montserrat Torremorell, DVM, PhD, University of Minnesota.

Most PRRSV-control efforts have focused on sow herds. As examples, Torremorell cited gilt acclimatization, PRRSV stabilization and herd closure — all aimed at protecting the sow herd and producing a PRRSVnegative pig.

Likewise, she said, biosecurity investments have focused on protecting sows. Examples include air filtration; disinfection of supplies; showering in; bench-entry systems; cleaning, disinfection and drying of weaned trailers; as well as downtime, dedicated personnel and dedicated transport.

Despite these efforts, various studies indicate the annual incidence of PRRSV hasn’t dropped significantly and is still found in 20% to 30% of US sow herds (Figure 1).

The focus on protecting sow herds is a starting point, but to further improve PRRSV control, there needs to be a focus on PRRSV in finisher pigs, Torremorell asserted.

Currently, there’s little effort to prevent infections in finishing sites, yet there is evidence that PRRSV is a growing problem in finishers and that these animals pose a risk for infection to sow farms, she said.


In one study, 38% of finishing-pig groups (243/639) negative for PRRSV at weaning were positive at marketing; 39% (247/639) of groups were positive at both weaning and marketing.1 In another study, 26% (31/120) of groups negative at weaning were positive at marketing.2

Annual losses due to PRRSV based on records from 2005 to 2010 were $664 million, and 55% of that amount was attributed to losses in growing herds. Data from 2016 indicates that losses due to PRRSV were $581 million (adjusted for changes in prices and the national herd size), and the percentage attributed to losses in growers had risen to 62%,3 Torremorell said.

The prevalence of PRRSV in finishers varies widely by region and may be as high as 62% to 84% based on information Torremorell obtained from colleagues at the Ohio State University.4 “So, there’s a lot of PRRSV in the finishing population,” she said.


In addition, emerging data from investigators at the University of Minnesota5 indicate that when pigs are moved to finishing sites near sow farms, they may introduce pathogens to sows through area spread. In other words, when pigs positive for PRRSV move into a farm “neighborhood,” there’s an increased risk that neighboring sow farms will become infected with the virus, Torremorell said, noting that the median number of pigs moving weekly into an area can range from under 2,000 to tens of thousands.

Unfortunately, not much is known about risk factors for PRRSV infection in finishing pigs, she continued, but her personal experience indicates biosecurity is sorely lacking on many finishing farms.

“I don’t go to any sow farms in the US where I don’t have to shower. I can’t say the same for most of the grow-finish sites I visit,” she continued. “We don’t even try to do some of the basic things on finishing farms…and don’t really monitor them.”

The failure to aggressively prevent PRRSV on finisher sites could be due in part to mindset. Producers may figure that if they’ll be emptying the site in the weeks ahead, it doesn’t matter if the animals get infected. “But if you start thinking in terms of implications for the neighborhood, then that assumption isn’t very good,” Torremorell continued.


The veterinarian also addressed marketing strategies that may contribute to PRRSV infection. Anecdotal evidence indicates the virus in previously negative pigs is associated with marketing the first load of pigs. Infection with PRRSV could be linked to contamination of trucks, trailers and drivers, to loading procedures or perhaps to collection of cull animals at multiple sites.

Other marketing practices that appear to be linked to PRRSV infection in finishers include failure to wash the facilities between groups of pigs and poor employee retraining about biosecurity procedures, Torremorell said.

Because information about PRRSV in finishers is limited, the University of Minnesota has planned a study. It will focus on determining the PRRSV incidence among pigs in medium-density areas. The study will also evaluate risk factors associated with PRRSV infection in growers and the production and economic impact of the disease, she said.

“My assumption is that if we can control the risk of infection in finishers, we could potentially lower the risk of infection on sow farms,” an approach that could bring PRRSV control to the next level, Torremorell said.



1 Holtkamp DJ, Kliebenstein JB, Neumann EJ, et al. Assessment of the economic impact of porcine reproductive and respiratory syndrome virus on United States pork producers. J Swine Health Pro. 2013;21(2):72-84.
2 Robb C, Holtkamp D, Yeske P, Lower A, Lowe J, Polson D, Lasley P. Evaluation of biosecurity measures and management variables as risk factors for infection of growing pigs that are negative at placement with porcine reproductive and respiratory syndrome virus. Proc Am Assoc Swine Vet. p:75.
3 Dr. Torremorell’s personal communication with Derald Holtkamp, DVM.
4 Dr. Torremorell’s personal communication with Andréia Arruda, DVM, PhD.
5 Morrison Swine Health Monitoring Program, Feb. 24, 2017.



Posted on April 9, 2018

tags: , , ,
  • Understanding which farm factors drive Influenza infection

    US producers and veterinarians have seen an influx of different types of influenza viruses in the last 10 to 15 years, and that is a major reason why influenza is more difficult to control.

  • Common mistakes to avoid during PRRS elimination

    Eliminating porcine reproductive and respiratory syndrome (PRRS) virus from a breeding herd is not a simple task, and no herd acts exactly like the next, according to Brad Leuwerke, DVM, with Swine Vet Center, St. Peter, Minnesota.

  • African swine fever, PRRS among hot topics at 2021 Leman Conference

    Organizers are excited to hold the 2021 Allen D. Leman Swine Conference in-person as well as virtually, on Sept. 18-21 in St. Paul, Minnesota.

  • Internal biosecurity essential to endemic disease control on pig farms

    Establishing effective internal biosecurity protocols is critical to breaking the circular spread of influenza and other pathogens between sow farms and growing sites, according to Montserrat Torremorell, DVM, PhD, University of Minnesota.

You must be logged in to edit your profile.

Share It
It’s not unrealistic to say that if you checked the nasal cavities or tonsils of any group of pigs, you would find Strep suis. While the strain and impact can vary widely, this commensal bacterium is on virtually every hog farm.

Click an icon to share this information with your industry contacts.
Google Translate is provided on this website as a reference tool. However, Poultry Health Today and its sponsor and affiliates do not guarantee in any way the accuracy of the translated content and are not responsible for any event resulting from the use of the translation provided by Google. By choosing a language other than English from the Google Translate menu, the user agrees to withhold all liability and/or damage that may occur to the user by depending on or using the translation by Google.