Just the words porcine reproductive and respiratory syndrome (PRRS) can strike fear into the minds of producers and their veterinarians. And as more strains are exposed, PRRS seems harder to control than ever. Four veterinarians took the stage at the 2024 World Pork Expo to share their knowledge on PRRS and other endemic diseases.
Dr. Guilherme Cezar is with Iowa State University’s Veterinary Diagnostic and Production Animal Medicine. He says every case that’s submitted to the lab is aggregated and the eight endemic pathogens that are tested and submitted give a big picture look at swine diseases in the U.S.
“Last year, PRRS had the highest number of cases tested so we’re investigating more,” he says. “When you look at the diversity of PRRS there are many strains.”
On a brighter note, he said there hasn’t been a single case of transmissible gastroenteritis (TGE) reported in the U.S. since 2021 so it appears the disease has been eradicated.
The same can’t be said for porcine epidemic diarrhea virus (PED). “We saw more activity this past winter, especially on the wean to finish side,” says Cezar. “Lateral breaks caused increased activity.”
Dr. Lisa Becton, associate director of the Swine Health Information Center says the goal of the Swine Health Information Center is to reduce the impact of emerging diseases on U.S. swine herds. “We look at animal health data and work to identify what’s not normal,” she says.
The Center originated in 2015, two years after PED appeared in the U.S., explains Becton. “We didn’t realize the disease was coming or the impact it would have on the industry so we knew we needed a way to identify emerging diseases and what pressures were out there.” The Center funds the swine disease reporting system as well as the Morrison Swine Health Monitoring program.
As an example, she said a porcine astrovirus was recently discovered, which instigated further research.
“The research helps us determine if this is something we need to be involved with or if it’s an incidental finding,” she says. “Our goal is to identify changing trends… and whether or not we have the appropriate tests.”
In the Field
For the last 16 years, Dr. Laura Dahlquist has worked with the Swine Vet Center and some of the most influential veterinarians to help producers have healthy sows and pigs.
“We build plans and protocols for testing,” she says. “We value healthy sows and producing pigs that everyone would want to raise.”
She noted that the newer strains of PRRS have been devastating in sow farms. With those strains, the decision to depopulate would be made right away, “but we still need to look at the history (can we keep the herd negative after depopulation?) and are there things we can do to improve the biosecurity, including education and training of the staff? Also, what’s the area like around the sow farm and does the farm have gilts for repopulation? Can I get the sows culled quickly? Are there other sow farms in the area that we want to protect?”
It’s critical those questions are addressed before depopulation is implemented, she says. Some herds can be stabilized if they aren’t dealing with a bad strain and there aren’t other farms nearby, but she is less likely to try stabilization because of recombination of the virus if animals are positive.
“We now see high-pathogen PRRS and it’s difficult to clean up,” says Dr. Deb Murray, veterinarian with New Fashion Pork. “If you can tell early on how severe it’s going to be, that can help your decision of whether or not you should depopulate. We’ll sequence three to five times early in the process and if we see a tiny change, that means it’s changing quickly – that tells you it’s going to keep doing that and you’re going to have a tough time getting rid of it.”
New Fashion pork has 60,000 sows and produces 1.2 million pigs/year.
“My passion is solving problems – I’d rather prevent a disease than have to go in and treat it,” she says. “We want them to come in healthy and stay that way so we work on biosecurity.”
All four veterinarians reminded producers to keep the basics in mind in controlling endemic disease. Make sure feeders and waterers are working properly. A feed outage, water issue or improper ventilation can open the door for disease challenges. Nutrition is the other part of the equation and plays a large role than people realize, says Dahlquist.
“We start with the simple things,” says Murray. “We look at building design and barn design. And just because something used to work doesn’t mean it’s working now.”
The farm staff needs to know the importance of herd health, points out Dahlquist. “Provide clarity and training for the staff, validate through assessments and observation, then review the process and find ways to make it better.”
Testing also is critical in determining what viruses are circulating in the farm, particularly since co-infections are common.
“There’s never just one virus…and we need to know how many we’re dealing with,” says Murray. “It’s like pealing back an onion: Nine times out of then there are more things there than you know.”
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