For decades, swine health research often focused on a single pathogen. However, experts pointed out during a recent Boehringer Ingelheim webinar hosted by Farm Journal that producers are actually dealing with the interplay of multiple health challenges over time. Nick Gabler, DVM, professor in animal science at Iowa State University, started researching these factorial health challenges about a decade ago.
He believes the sow farm is the true starting line when it comes to swine health. Although disease often manifests in the nursery or finisher, the root cause frequently traces back to the sow farm.
“We’re seeing that sow farm health has a big impact on that first three to four weeks in the nursery,” Gabler says. “There’s a lot of multi-factorial health challenges there. That’s where I see opportunity for the swine industry to clean up the sow farm and create a downstream impact on health and performance of the pig.”
The Multiplier Effect
Most research focuses on the onset of an infection. However, the economic impact isn’t just about how many pigs get sick, but how quickly and efficiently they recover, Gabler says. A pig that “lingers” in a subclinical state is often more expensive than one that recovers quickly, as it continues to consume resources without gaining weight.
This approach of dynamic pig health, or understanding the full picture of the problem, requires producers and veterinarians to ask some tough questions.
“What is the pathogen or stressor involved?” Gabler asks. “When is it coming into your operation? How does it interact with your management decisions (feeding, marketing, people movement, truck movement, medication and vaccine use)? What pathogens are present?”
Just as importantly, it’s important to consider if the pig can recover and get to full value in time, he says. In short, it’s understanding the big picture and then intervening where you see the most benefit.
But that’s not easy math.
“One plus one does not equal two with the disease world. One plus one equals three, and a lot of times, four,” says Clayton Johnson, DVM, director of health for Carthage Veterinary Services. “That’s tough for a farmer to hear that the pieces of the puzzle don’t fit together well, but that’s the honest answer you’ve got to give them sometimes.”
No Two Pigs Are Alike
Dynamic pig health understands that no two pigs are going to get sick in the same way, says Lance Mulberry, an economist with KnowledgeVentures.
“Between no impact to mortality, there is a huge range of effects that can happen,” Mulberry says. “Dynamic pig health is a shift in mentality away from thinking of our herd as one unit, where every pig gets sick at the same time, has the same impact and recovers at the same time, to a population with complexity. This impacts that opportunity cost at the end because you’re going to have some pigs that just struggle a lot – I call those opportunity pigs.”
In a low-margin industry, the difference between profit and loss often lies in the “opportunity pigs” or the 20% to 30% of the herd that struggles to reach target weights due to health burdens.
“If you’re a producer and you’re trying to optimize your profits, you’re trying to hit a moving target that is changing from day to day and week to week,” Mulberry says. “When we throw disease in, especially a co-infection, we are making that target – that optimal profit point – move even more. Hitting that target in the best of scenarios is difficult to do, but with disease it can become a real challenge. Anything we can do to get a better idea of what is happening to individual pigs will make optimizing profit a little bit easier.”
PRRS is the “Trojan Horse” of the Barn
Even when pigs from different sources appear healthy and have no “bad actors” on a diagnostic report, mixing them often triggers disease, Johnson says. Mixing populations is a major catalyst for dynamic health challenges.
Porcine reproductive and respiratory syndrome (PRRS) remains the primary driver of coinfection complications because of how it systematically dismantles the pig’s defenses.
“PRRS makes everything else harder,” Johnson says. “PRRS is an excellent Trojan horse. It comes into the immune system and affects macrophages whose job is to be the police on the street looking for the bad guys.”
PRRS gets in those macrophage cells and causes apoptosis.
“Those ‘police on the street’ are now dead men walking,” Johnson explains. “They’re not out there finding the bad guys and bringing them to the immune system anymore. That allows PRRS replicate within the pig, pretty unchecked for several weeks, until eventually, the pig’s immune system figures out what’s going on and builds antibodies.”
During that period, imagine an entire city without police, Johson continues.
“On night one, it’s not a big deal. Night two, not as much of a big deal. But night three, once the bad guys have realized there’s nobody to catch them, that’s where you start to see problems,” he says.
The list is long of pathogens that can’t wait to take advantage of that situation. In short, it’s an “unwinnable battle” because the pathogens have the upper hand.
“We have to figure out a way to change the rules of the game in order to put the pig in a position where it can have the upper hand,” Johnson says.
The “Silent Thief": Subclinical Disease
Not all losses are visible. Subclinical infections are diseases that don’t cause obvious clinical signs or mass mortality. For example, subclinical Lawsonia (ileitis) can significantly worsen PRRS outcomes, even if the producer never sees a bloody gut.
“Subclinical diseases are like your taxes. They take it out before you get the money,” Johnson says.
Dynamic disease contributes to opportunity pigs and prevents producers from optimizing those opportunity pigs.
“What happens at the end of every all in/all out group of pigs?” he asks. “You have somewhere around 15% to 20% of your pigs left. What do you do? You dump them. You sell them all, no matter what weight they are right then, and you take a huge penalty by doing that.”
To minimize subclinical impact around diseases like Lawsonia, Fernando Leite, DVM, associate director of technical marketing at Boehringer Ingelheim, encourages producers to consider how they can optimize immunity and protection to the pathogens the pigs will likely face in the field.
It’s important to keep in mind that not all protection is equal. Using vaccines that are homologous to the field strain where possible can significantly reduce viral load and lesions compared to heterologous vaccines.
The Windshield vs. the Rearview Mirror
Edison Magalhães, DVM, assistant professor of animal science at Iowa State University, encourages producers to incorporate more real-time data into health decisions. Closeout reports are “rearview mirror” metrics, but real-time data on water and feed consumption acts as a “windshield” that allows producers to see a health challenge before it becomes a wreck.
When coinfections and health challenges occur, the temptation is to change every variable. However, Gabler warns this prevents producers from finding the root cause.
“If you try to change too many things at once, you’re never going to get to what the true cause was,” he says.
Read more:
When “Something is Off": Identifying the Subtle Shift of PCV2d
It’s Time to Unravel How Multiple Swine Pathogens Interact in the Pig
