Author: Tim Lundeen

The Swine Disease Reporting System (SDRS) is a tool developed by a consortium of veterinary diagnostic laboratories in cooperation with the Swine Health Information Center to share information on endemic and emerging swine diseases so veterinarians and producers can make informed decisions on disease prevention, detection and management.

Dr. Paul Yeske with the Swine Vet Center explained that the monthly SDRS reports allow the swine industry to monitor trends and predict when herds might be at a greater risk of an outbreak.

The SDRS – led by the Iowa State University Veterinary Diagnostic Laboratory with participation from the University of Minnesota Veterinary Diagnostic Lab, the South Dakota Animal Disease Research & Diagnostic Laboratory, the Kansas State Veterinary Diagnostic Laboratory and the Ohio Animal Disease & Diagnostic Laboratory – helps veterinarians better understand the epidemiology of particular pathogens moving among swine populations, Yeske said.

For example, in the last four years, whenever there has been an increase in porcine reproductive and respiratory syndrome virus (PRRSv) activity in grow-finish units, there tends to be an increase in positive cases in sow herds a month later. So, when PRRSv activity is trending up in the grow-finish barns, nearby sow farms may want to make sure they’re doing everything possible relative to their biosecurity protocols to reduce the risk of the virus spreading into nearby sow units.

(This is the breakdown of the different phases of production showing the turn up in PRRS in wean to finish.)

SDRS also reports data on a geographic basis, so users can look at what regions are hotspots for a disease and then act accordingly to minimize pathogen spread, he added.

Yeske likes to compare the monthly SDRS report against the weekly Morrison Swine Health Monitoring Project reports because they use different approaches to examine data. “The Morrison project is based on farms reporting clinical signs they’re experiencing, while SDRS uses diagnostic data from university veterinary labs.” said Yeske. It is interesting to see it from two different perspectives can identify similar trends.

He noted that the SDRS has a bias in that it is based on diagnostic data, so the data is derived from people looking for a problem, but it is still valuable to look at as an industry because at least you know what people are out looking for and then what they’re subsequently finding when looking at a particular population.

SDRS also reports viral sequencing, so users can compare the virus strains they’re dealing with in their herd compared to what is circulating in the broader industry, Yeske said, noting that more recently, PRRSv strains 1-4-4, 1-7-4 and 1-8-4 have been the top three viruses circulating, along with the vaccine virus.

Porcine epidemic diarrhea (PED) virus, mycoplasma and influenza are also tracked by SDRS. Yeske adds, “PED incidence has been occurring more in the January time frame, so producers can be aware and start to monitor for early signs of the virus as winter approaches. Similarly, mycoplasma tends to drop off in the summer and go up in the winter, so steps can be taken to reduce the risk of mycoplasma entering a herd and hopefully head off any outbreaks before they happen.”

The SDRS predictive model is based on the three previous years with some statistical analysis, Yeske explained. In the report, for each pathogen, there’s a shaded zone where the report authors believe normal activity should be, so if the trend line jumps out above that shaded zone, there’s more activity going on, or if it drops to the underside, there’s less activity.

Surprises

Yeske said the biggest surprise in the current reporting is that the swine industry has started to turn the corner on PRRSv on grow-finish operations. He said in the previous few years, PRRSv has started to increase in grow-finish in August and early September, but this year, the virus has held off until September.

For PED, he said there was more activity last winter and spring, but that went back under control over the summer, so the overall PED numbers have come down and “we’ll have to see what happens this winter.”

Long-term value

Yeske said the long-term value of reviewing  the monthly SDRS reports is the ability to get that predictive interpretation and to see what is happening across the swine industry, not just in a single herd or system. “Sometimes, it feels like you’re the only one that’s breaking (with a disease), and well, the reality is a lot of herds are breaking, so there is value in understanding what is going on with the rest of the industry,” he added.

On the SDRS website, Iowa State also has a dashboard that allows users to dial in and take a closer look at the data and proactively notice trends in a particular geography for a particular pathogen. These tools can help users maintain awareness of pathogens that are affecting their herds but may not be getting industry-wide attention.

Yeske noted that last winter, the SDRS reports showed increased activity of acute pleuropneumonia (APP), which hadn’t been seen for a while but was spreading among grow-finish operations.

There is value in accumulating diagnostic information, Yeske said, because SDRS brings together data from multiple sources and puts them in a single place where additional analytics can be applied to create better disease management tools. In the past, these data were in individual research projects or individual reports that stakeholders would need to search for, but now, with the SDRS dashboard, users can view the monthly report and get a summary of what is happening across the industry.

Deeper diagnostics

In addition to the surveillance data from PCR sampling for influenza, mycoplasma, PRRSv and PED, the SDRS reports also look at tissue cases – where the diagnostic labs do more specific tests on submitted tissue samples, Yeske said. These tests show everything that is found in a particular sample and how those relate to each other. For example, on enteric cases, is the most common pathogen rotavirus, an Escherichia coli or a clostridium? And because of the overlap many cases have, which is more dominant, and which may be secondary infections?

Typically, when a veterinarian sends in a tissue sample, he/she is trying to solve a health challenge that needs more diagnostics than ongoing monitoring may provide.

Overall, the value of tools such as the monthly SDRS report is to provide producers and veterinarians information on the disease trends occurring across the swine industry and within particular geographies so that they can make informed decisions about disease prevention and management.

Visit The SDRS website for various reports, dashboards and podcasts that summarize key content and data.

Many successful truck wash operations utilize an internal audit system where someone is responsible for monitoring processes as trucks and trailers move through the wash, according to Dr. Erin Kettelkamp with the Swine Vet Center.

What should these audits or assessments include? Kettelkamp uses an evaluation form that helps her gain a good understanding of the day-to-day practices at a truck wash. Her goal is to understand the flow of traffic throughout the day, how many trailers are getting washed each day, whose trailers are getting washed, and the logistics associated with individual truck movement. From there, she wants to understand the company’s expectations for washing standard operating procedures (SOPs) and whether the behaviors – what is actually being done in the truck wash – match the written SOPs.

“If the goal at the end of the day is to have a very clean trailer, it’s important that we’re measuring and assessing that process,” Kettelkamp said, noting that inspecting a trailer while it’s still in the wash bay helps ensure the wash crew has gotten into the hard-to-reach areas, and if necessary, allows them to rewash missed areas without having to pull a trailer back into the wash bay.

She said some of those hard-to-reach areas include the ceilings in the lower levels where there can be spray residues, along the support rails where dust can accumulate, and behind gates and hinge points. Kettelkamp said in trailers with multiple decks, the ramps don’t always get pulled out fully during the wash process so shavings and other materials may hide there and re-contaminate the trailer.

Depending on the configuration of a trailer, the nose of the trailer may have different angles and supports that a washer – normally facing the front of the trailer while washing – may miss because they may not turn around and find the non-standard hiding spots.

Kettelkamp said the focus of the wash crew should be to remove all organic material in order to implement an effective wash. “First and foremost, we have to do a really good job with the initial power wash. We can layer on all the disinfectant we want, but if we’re not getting the initial wash done right, then disinfectant and all those other steps really aren’t going to help us any,” she said.

For the disinfectant step, she said a variety of disinfectants are used throughout the swine industry, and as long as they’re verified to be efficacious against all of the major pathogens, they tend to do a good job if the trailer has been thoroughly power-washed first.

This includes the outside of the trailer, especially the wheels, wheel wells and belly of the trailer, which should all get a good full rinse. She suggested that during the winter, if the snow and slush is not getting cleaned off the outside of the trailer, and if trailers are being pulled out of wash bays that haven’t had time for the ice to melt off, the wash crew is probably not doing a very complete job.

Kettelkamp said a best practice should be to have trailers washed between each use, but from a logistics standpoint, the industry hasn’t been able to move in the direction of fully washing between every downstream trailer movement. She said a general expectation would be that trailers coming into contact with a sow farm or other high health site should be washed, cleaned and disinfected before every use.

Automation

Kettelkamp noted that there’s been some discussion about automated truck wash bays for the cleaning of feed trucks and other vehicles that may be entering pig production sites. These systems may help decontaminate wheels, wheel wells and the bellies of vehicles that do not come in direct contact with animals. The poultry industry has installed some of these automated systems, but Kettelkamp is not aware of any in use in the swine industry.

Otherwise, washing trailers is back-breaking work, especially when scraping and washing triple- or quadruple- deck trailers, so some type of automation could help in those situations.

Baked trailers

According to Kettelkamp, some swine companies have been “baking” trailers as an extra step in the process. To do so, the wash bay or other room is heated until the surface of the trailer reaches a temperature of 160°F for at least 10–15 minutes to deactivate viruses such as porcine reproductive and respiratory syndrome virus (PRRSV) and porcine epidemic disease virus (PEDV).

She noted that the process can also be effective if the trailer is heated to a lower temperature that is held for a longer duration to dry out and bake the trailer.

A full cycle time for a truck to enter a bay and heat the room long enough for the surface of the trailer to reach 160°F for 15 minutes can take more than 1 hour, depending on the external weather conditions, Kettelkamp said.

Surrounding truck wash biosecurity

Beyond looking at the cleaning practices of trucks and trailers, Kettelkamp said it is a good idea to look at the biosecurity of foot traffic and vehicle traffic around a truck wash.

Wash facilities should be set up in a linear arrangement or potentially in a circle, where dirty trucks or vehicles may enter on one side or through one driveway and nothing gets past a line until it goes through the wash and disinfection process before it can be on a designated clean side of the wash.

That way, she explained, cross traffic between vehicle employees and/or maintenance trucks on the site is minimized. There should be clear lines of demarcation of “this is dirty” versus “this is clean” and our washes should be managed that way, she said.

The site for the truck wash also should be carefully chosen so clean vehicles are parked upslope from unwashed trailers; in the case of rainfall, runoff from dirty trailers should not flow to where clean trailers are parked, exposing them to recontamination, Kettelkamp said.

“We should have the same thought processes and practices for entering a truck wash as we do for entering a sow farm. How do we minimize cross contamination within our buildings or setup and how do we keep trailers clean and minimize foot traffic in and out? What are our designated dirty areas? What are designated clean zones for foot traffic on a wash?” she said. “We know we’re dealing with a lot of fecal material, but if we’re tracking it all around the site and potentially re-contaminating other areas, including trailers that were initially clean, we’ve got to think of a better way to mitigate that risk.”

Developing truck wash SOPs, validating, and assessing how well those SOPs are employed and considering how vehicles and personnel move around a truck wash are all key aspects that will help improve site biosecurity.

The hot, humid days of summer often bring the challenge of coccidiosis in pre-weaned piglets in the farrowing barn, but that challenge has now become more prevalent year-round, according to Dr. Laura Bruner with the Swine Vet Center in St. Peter, Minn.

In the last couple of years, coccidiosis in young pigs has been a hot topic because the disease management tools available in the past have not been available due to supply chain issues, she added.

Typically, the classic presentation of a coccidia infection on a sow farm is a yellow and pasty diarrhea that develops around 7–14 days of age in piglets. The diarrhea is very noticeable – it’s thicker, not a watery diarrhea that would go through the flooring – and it builds up in the crate and environment, she explained.

Coccidiosis generally does not cause mortality in piglets but does cause significant loss of gain – so it wouldn’t be surprising for pigs with a heavy coccidia infection to weigh 1–2 lbs. less at weaning than uninfected pigs. “It definitely hurts the gain of the pig, and when you talk about gain in pigs, that’s everything. How fast can I get them to market?” Bruner said.

Along with coccidia challenges, secondary infections are possible because enteric cells of the gut become disrupted, which allows other enteric bacterial and viral pathogens to invade the intestinal lining. These secondary infections are more likely to cause mortality, especially if the pig becomes really chronic.

Prevention and control

It takes seven days for coccidia to mature and sporulate oocytes, which are then shed allowing infection to spread. Anti-coccidial or anti-protozoal medications such as ponazuril (trade name Marquis) have been developed for other animals such as horses and companion animals that kills coccidia at the right time in its life cycle so sporulation does not occur.

With a valid veterinarian-client-patient relationship (VCPR), veterinarians can recommend these medications for use in piglets. Oral administration of ponazuril to piglets starting on day 3 would break the sporulation cycle and eliminate coccidia from the farrowing unit environment.

However, due to supply issues, product availability is low and what is available typically goes toward horses. This has left the swine industry without many preventative tools, Bruner said.

Given that coccidia are exceptionally hardy organisms that build up in the environment, if a producer never has a way to decrease coccidia shedding or decrease the environmental load in their barns, it just continues to build up. “I think that’s part of the reason why we’ve more recently had problems in the winter, when we wouldn’t typically have them, because we haven’t been able to knock down that cycle,” Bruner added.

There are other products developed for cattle and poultry species that have been tried under the VCPR provisions that allow the use of medications off-label, but those products are not coccidiacidal – so they don’t kill the coccidia – but are coccidiostatic, meaning they inhibit coccidia’s life cycle but don’t eliminate it.

Generally, coccidiostats need to be fed continuously to keep the coccidia at bay so disease can be prevented until the pigs are weaned off the farm. Bruner added that this option is labor intensive and not that effective, since the piglets really need to consume the coccidiostat for the entire period they’re in the farrowing unit, meaning the return on investment for this practice is not good.

By providing a coccidiostat, Bruner said clinically, the disease effects get better but the coccidia are not gone. “I think all it’s really doing is decreasing the environmental load to give you a chance to sanitize your way out of it,” she said, leaving the industry kind of stuck between a rock and a hard place.

Whitewashing

To sanitize against coccidia, historically, producers would use a very strong bleach or ammonia solution when cleaning a farrowing room between groups, but those solutions can create human safety concerns.

Instead, producers have moved to whitewashing – spraying hydrated lime and coating the crates and all of the contact areas that piglets would touch – to try to eliminate coccidia with a really high pH solution.

Bruner said whitewashing has been fairly effective, but the right amount of hydrated lime needs to be applied in a thick coating on all contact surfaces for it to work well.

With coccidia challenges extending throughout the year, producers may have to start applying whitewash earlier in the year, such as in March or April, and not wait until June or July when it gets hot and there already are coccidia problems, Bruner said.

Another key step, Bruner said, is to routinely inspect sanitization efforts – after sanitizing the room, ask “how good of a job did I do?” and then after the room is sprayed with whitewash, ask again, “how good of a job did I do?” Inspect what you would expect to see and how well you covered contact surfaces.

Post-weaning

After weaning, coccidia is less of a problem, but if secondary infections were present in the farrowing crate, there can be lingering effects in addition to other post-weaning stresses.

There is a portion of the population that doesn’t recover from a coccidia infection, but for the most part, it is mostly a weight-loss issue, depending on how fast the pig’s intestinal tract can heal. Any post-weaning infections with rotavirus or E. coli will just add fuel to the fire of health challenges.

According to Bruner, the key to managing coccidiosis is knowing when it will be at its peak and getting ahead of environmental contamination. Coccidia enter the farrowing house from animals – typically from gilts that may be shedding – so in theory, batch systems would have fewer issues.

Once coccidia gets into a farrowing house, it is hard to get out, but staying on top of sanitization practices and inspecting procedures to ensure full coverage will help minimize any health and performance challenges.

While biosecurity remains the best option for managing Actinobacillus pleuropneumoniae (APP) outbreaks in swine finishing barns, the recent APP outbreaks in the Midwest has spotlighted biosecurity gaps in this phase of production, according to Swine Vet Center veterinarian Dr. Ethan Spronk.

APP is a gram-negative bacteria that requires swine as its host. There are 15 known serotypes, with serotypes 1, 3, 5 and 7 the most common, Spronk said, noting that serotype 15 is a newer strain currently challenging the industry.

Clinical signs of APP include sudden death in finishing hogs, especially in the mid-weight to early marketing periods, with occasionally bloody discharge from the nose. Prior to death, pigs experience respiratory distress, open-mouth breathing or gasping for air. On necropsy, lungs are found with dark purple abscesses with adhesions. Death is often caused by cyanosis – decreased oxygen supply to tissues – from the adhesions and abscesses in the lungs, Spronk noted.

APP develops very quickly once it starts, he said, and it is usually set off by a stress event – poor ventilation, high outside temperatures, other viral or secondary challenges or outbreaks, as well as sorting and/or loading for marketing purposes.

APP is spread on fomites, such as all the equipment – i.e., boots, coveralls, sorting panels, shockers, etc. –used for sorting/loading or mortality removal, he said.

Treatment of APP is a whole-herd or pen antibiotic injection, Spronk said, noting that products that have been the most successful include enrofloxacin (Baytril^® or Enroflox^®), tulathromycin (Draxxin^®) and ceftiofur (Exenel^®/Naxcel^®). See product labels for use directions, etc.

There are also autogenous vaccines that offer cross protection among APP strains, he noted.

Biosecurity protocols

The recent APP outbreak is focusing attention on finishing unit biosecurity, Spronk said, explaining that due to porcine reproductive and respiratory syndrome (PRRS) and porcine epidemic diarrhea, a high degree of attention has more typically been placed on sow farm biosecurity, but finishing barn biosecurity practices haven’t gotten the same attention until now.

At least nine central Iowa pork production systems have been affected, but there doesn’t appear to be a common link among the systems. Iowa State University has been diligently seeking to better understand the epidemiology of the current outbreak as it seems to be moving differently through pork flows compared to prior outbreaks with more lateral breaks versus the usual sow farm flow outbreaks.

One concern identified in Iowa, Spronk said, was the presence of rendering trucks on affected premises, or epidemiological links were identified to positive sites that did have rendering trucks, a common service provider or marketing crew.

These findings highlight the need for good biosecurity on swine finishing sites, Spronk said. Barns should be set up with a “clean/dirty line” at entry, and personnel should wash hands and change boots and coveralls on entry to a barn. When doing chores in barns, personnel should think through how they move through the barns, working the smallest, healthiest pigs first and moving toward the oldest pigs, he added.

Separate equipment and clothing should be used inside the barn when removing mortalities, with dedicated sleds/carts outside the barn to move dead animals to the rendering box. Mortality collection points should be far enough away from buildings to avoid the potential for cross traffic with where the rendering truck would travel, Spronk said.

He suggested that adopting composting or incineration could be better options for mortality management instead of rendering to avoid disease spread, especially as the industry considers the potential for foreign animal diseases such as African Swine Fever (ASF).

Spronk noted that if producers experience sudden or high death loss in their finisher units, it is important to contact a veterinarian because it is critical to determine which disease(s) are present. While ASF has a different pathogenesis, it shares some visible symptoms with APP, so it needs to be ruled out. Also, PRRS and influenza can be coinfections with APP that can trigger an APP outbreak.

According to Spronk, in the past, APP would have been flow dependent, so on an APP-positive sow farm, those pigs would get exposed in the farrowing crate and then when a stressor hits them in finishing, a disease outbreak would occur. A lot of systems moved to eliminate the virulent APP strains because outbreaks would be so costly producers couldn’t live with them.

Depopulation is the best way to clean it out completely, he said, noting that the cost of medication programs to control APP is expensive, so removing the positive sows from a system is the better option.

APP has been extremely costly to the industry, with the highest value mortality happening right before marketing. Once it gets into a system, it is harder to stop APP, Spronk concluded, leaving the best option to be prevention through good biosecurity and keeping the disease out of a pig production system.