Everyone experiences pain in life. Sometimes, if the pain is excruciating enough, it results in transformational change. The current pain level of porcine reproductive and respiratory syndrome (PRRS) in the U.S. is extreme, says swine veterinarians Scott Dee and Gordon Spronk. That’s why they are calling for transformational change in a viewpoint article in the Journal of the American Veterinary Medical Association.
Dee and Spronk say it’s time to create a world without PRRS.
“We aren’t in the spring of our careers anymore,” Spronk said during an exclusive on The PORK Podcast. “We’re in the fall of our careers, and maybe it’s time to be reflective and hopefully speak into and encourage the next generation of pork producers that their life can be better. And not only their life, but the life of the pig, will be better if we had a world without PRRS.”
Why Now?
For more than 38 years, Spronk and Dee have been working side by side to fight PRRS. Why should the industry move to eradicate PRRS now?
“I have a long history as a veterinarian, but my family also raises pigs. We’re in the middle of a generational transfer,” Spronk explains. “It’s important for the next generation who will take over this operation to be encouraged about the potential of productivity, and what could clearly be achieved if we didn’t have PRRS circulating in our sow farms.”
The U.S. swine herd is currently dealing with variants such as PRRSV L1C.5 and L1C.2 that are spreading rapidly. These variants are more infectious than previous isolates, as well as highly pathogenic.
“These highly pathogenic isolates are moving around in areas between wean-to-finish barns, meaning that you can have your sow farm negative produce a group of negative pigs, place them negative, but then they become infected with lateral transmission,” Spronk says. “And our national swine herd mortality is to the level that it’s concerning from a productivity standpoint and competitiveness with other international competitors, namely Brazil.”
Field observations indicate pre-weaning mortality levels ranging from 56% to 100% post-infection, resulting in losses of $1 million to $3 million per 10-week period post-weaning, not to mention compromised animal welfare and compromised mental health among workers.
“The thing that really gets me about this one is the welfare aspect,” Dee says. “It’s the suffering that the animals and the people working on the farms go through. It’s worse than I’ve ever seen it. We know that only pigs can get PRRS, but people suffer when they watch animals die and work so hard to treat them. That to me, is a welfare aspect, along with the economics and the production issues that make this situation so difficult right now.”
What Does A World Without PRRS Look Like?
Dee says there are examples in negative barns of what a world without PRRS looks like – higher productivity, higher health pigs are more fun to raise.
“It’s a flourishing U.S. national herd with reduced antibiotic use, lower mortality, predictable productivity, and with satisfied employees working in a welfare-friendly environment,” Dee says. “In other words, a more profitable and competitive national industry for generations to come.”
Dee believes this could lead to freedom from other domestic diseases such as porcine epidemic diarrhea virus and strengthened prevention of foreign animal disease.
When Dee served as president of the American Association of Swine Veterinarians in 2005-2006, he called for national elimination of PRRS.
“It was the right thing to call for but it was ahead of its time,” Dee points out. “We were missing two things. We were missing a clear understanding of area spread. How do we prevent the virus from moving from farm to farm? We know a lot more about that. The other is US SHIP. We didn’t have a united platform that we could all work together on to kind of collectively come together with decisions as an organization rather than just an individual. Now it’s time to have that conversation again.”
Dee and Spronk outline six non-negotiable practices the industry needs to adapt to survive.
Non-negotiable #1: The U.S. swine industry must eliminate PRRS virus.
The successful disease elimination of pseudorabies, classical swine fever and foot-and-mouth disease can be applied to build strategies to eliminate PRRS virus from our national swine herd.
“PRRS costs our industry approximately $1.2 billion per year. Global competitors like Brazil, Romania, Chile and Denmark have either successfully sustained freedom from PRRS virus or are striving to achieve/have achieved national elimination. The longer we wait, the harder it will be to compete in the global marketplace,” Spronk says.
Non-negotiable #2: The U.S. swine industry must improve its biosecurity.
The U.S. must continue to raise the level of biosecurity across the national herd, through an evidence-based approach known as Next-Generation Biosecurity (NGB), Dee says. NGB targets prevention of viral entry into the breeding herd (bio-exclusion) via direct routes (pigs and semen) and indirect routes, i.e., mechanical routes, aerosols and feed.
“The same concept must be applied to the wean-to-finish sector through both the practice of bio-exclusion to protect standing growing pigs and the practice of bio-containment to protect the region,” he says. “This latter point stresses the need for strategies designed to reduce viral excretion from infected populations, such as the use of vaccines and the participation in voluntary animal health programs.”
Non-negotiable #3: The U.S. swine industry must restrict the use of live virus inoculation.
Live virus inoculation (LVI) involves the harvesting of farm-specific viruses through injection of serum from viremic animals to induce homologous immunity in susceptible animals.
“This practice is neither safe or efficacious, as the use of LVI in sows induces pregnancy loss across all stages of gestation, and does not produce sterilizing immunity,” Dee says. “In addition, when evaluating the productivity of PRRS-virus-infected breeding herds vaccinated with modified live virus vaccines (MLV) versus those administered LVI, MLV herds returned to baseline production significantly sooner and had significantly less total reproductive loss, versus herds given LVI.”
Routine application of LVI in pregnant females should be avoided and limited to a safer use as a one-time application to stable population of non-pregnant replacement gilts housed in a biosecure gilt development facility during a PRRS virus elimination program, Dee adds.
Non-negotiable #4: The U.S. industry must change its behavior regarding the movement of PRRSV-infected pigs.
Between-farm movements of animals and transportation vehicles enhance regional spread of PRRS virus, with vehicles transporting pigs to farms being responsible for most infections. To control the spread of the virus at the regional level, they are calling for change in how PRRSV-infected pigs are moved between sites.
“The co-mingling of infected and non-infected pigs at weaning must be avoided, infected pigs should not be placed near naïve populations of negative sow farm populations or standing growing pigs, and transport vehicles should be sanitized between movements,” Spronk says. “This is simple common sense. We know what we need to do, we just must do it.”
Non-negotiable #5: The U.S. industry needs an improved genetic response to PRRS virus.
Exciting advances are underway in the field of swine genetics pertaining to PRRS virus, Dee says. One approach is the editing of the CD-163 region of the macrophage to prevent viral infection at the cellular level, while the other involves genetic selection to improve the general immune response and robustness of the pig following challenge.
“Each approach has its own strengths and limitations,” Dee says. “I think we do have to temper our enthusiasm that there’s not a silver bullet for this disease. One size doesn’t fit all.”
Non-negotiable #6: The U.S. swine industry needs to participate in US SHIP.
Modeled after the National Poultry Improvement Plan and originally based on mitigation of African swine fever and classical swine fever, the US Swine Health Improvement Plan (US SHIP) has the ability to stimulate collaboration and reduce the impact of domestic diseases such as PRRS virus, they say.
Prior to US SHIP, a platform like this was not available, Dee says. However, the industry can now use this to communicate and collaborate more effectively.
“We are clearly ready,” Dee says. “There’s no question in my mind, after 38 years dealing with this thing, we are so ready. It hurts to sit still. Now is exactly the time to take all the information, all the collaboration that’s coming, and get going, because we know what we need to do. We just have to do it.”
Watch their exclusive interview on The PORK Podcast here or listen anywhere podcasts are found.
Read the viewpoint in the Journal of the American Veterinary Medical Association.
