Mycoplasma elimination possible, but more difficult on farrow-to-finish sites

With the right program in place, eliminating mycoplasma pneumonia is possible on many hog farms. Farrow-to-finish sites are still the most difficult to clean up, however, reported Swine Vet Center’s Paul Yeske, DVM.

He has carried out multiple mycoplasma-elimination efforts on different types of hog farms with good success.

“The farms that are easiest [to eliminate mycoplasma] are the farms that are multi-site production, where we have a farrow-to-wean site…The herds that have all ages of pigs on site, that’s where the challenge is going to be,” he said.

Long-term herd closure

The best method for eliminating mycoplasma from a farrow-to-wean site requires herd closure to allow the animals to develop immunity and stop shedding. Research shows the disease’s causative organism, Mycoplasma hyopneumoniae, can be shed up to 240 days.

“We expose all the animals up front to make sure everybody’s exposed and immune, and then we wait 240 days,” Yeske explained. “At the end, we use some medication as a secondary step to make sure we’ve controlled everything before we bring the negative animals back in.”

The advantage of this elimination program is a short payback period of a few months, he added. A depopulation-repopulation elimination takes a couple of years to pay back the expense.

Farrow-to-finish options

Farms with all ages of pigs on one site require more time and expense to eliminate mycoplasma. A partial depopulation that empties the nursery and finishing stages for a short time is one solution, according to Yeske.

“I think there are ways we can do [elimination] on really any given farm,” he said. “It’s just finding creative ways to do it. And the depopulation-repopulation would certainly be an option.”

Complete elimination

Could mycoplasma be completely eliminated from US herds?

“I think it’s a disease that could be eliminated,” Yeske stated. He cited research that showed a low likelihood of M. hyo reinfection from neighboring finishing units.

“If you have a mycoplasma problem in your system, you likely have a system problem,” he said. “It’s not the neighborhood problem.”

Plus, the future holds new technologies like better diagnostics, new antibiotics and new testing procedures.

“Are there ways we can manipulate these tools to eliminate disease so we don’t have to deal with it?” he added. “What I’ve tried to do over time is, when something new comes out, [to determine] how could we leverage this into a new tool.”

In the past, the pork industry has eliminated diseases like pseudorabies without depopulation-repopulation.

“We had a very good vaccine with pseudorabies, and we were able to do eliminations by test and removal,” Yeske recalled. “Mycoplasma is another bug that lends itself well to herd closure and elimination.”

Watch the interview with Pig Health Today:

Sow pads show promise for reducing shoulder sores, related infections

Everyone needs a good bed — and apparently sows are no exception.

During farrowing and lactation, sows can easily develop shoulder sores, which in turn become infected.  Could a little padding help?

Several producers are answering that question. Working with the Swine Vet Center’s Ross Kiehne, DVM, the group is testing a mat similar to a wrestling mat that’s placed under a sow’s shoulder to provide comfort and allow healing.

They found most shoulder sores will improve when the mats are used, especially when potential sores are first detected, according to Kiehne.

Developing the mat

“We have some producers who are very interested and would like to do what they can for the pigs,” Kiehne said. “If they can make the sows more comfortable, they know [the sows] will do better.”

The prototype mats are a half-inch thick and covered with a canvas-nylon material that can be sanitized. “We don’t know if we can hit them with a power washer but feel we can clean them pretty easily,” he added.

Sows can develop the shoulder sores when lying and lactating on the metal slats of the farrowing crate, Kiehne explained. The skin is a little softer, and the sores start just like bed sores. The sores worsen in the summer when it is wet or humid.

“[Sores] usually don’t lead to any mortality if they’re dealt with,” he added. “But if you left them alone too long, they would start to get an infection…that could be devasting to the sow.”

A mat in every crate?

The question arose about using a mat in every farrowing crate.

“It would have to withstand the washing and the wear and tear of being in [the farrowing room] full-time,” Kiehne said. “I don’t know if it’s ready for that or not.”

He plans to test the mats and see how long they last if left in the farrowing crates permanently.

Another question is if the mats could help with leg issues. “If you had a bad leg, you’d just put [the mat] in a different area,” he said. “That’s tougher because that’s where the manure is a lot of times.

“But any time you can improve comfort and then get them healed…and getting up and down, it is definitely going to improve the longevity of the herd,” Kiehne said.

Watch the interview with Pig Health Today:


Gilt acclimatization is key to eliminating Mycoplasma hyopneumoniae in sow herd

Successful elimination of Mycoplasma hyopneumoniae (M. hyo) from a herd is often driven by sow farm status, according to Alyssa Betlach, DVM, Swine Vet Center. Betlach has researched M. hyo for several years in a PhD program at the University of Minnesota.

Within the industry, M. hyo continues to be a prevalent and economically important respiratory pathogen worldwide. Studies have shown that the disease can add $3 to $10 per pig due to decreased animal performance, including longer time to market and increased antimicrobial usage, she added.

Traits of M. hyo

Three unique features of M. hyo must be considered when developing a control plan. First, piglets are not born with M. hyo but often are colonized from their mothers, who shed it during farrowing. The bacterium colonizes in the lungs of the pigs and causes clinical signs in grow-finish due to the slow, chronic nature of the infection.

Second, M. hyo primarily resides in the respiratory tract by adhering to lung cilia.  Therefore, “When you think of diagnostics and sampling, you need to consider that it resides deep in the lung,” Betlach said.

Third, shedding from M. hyo has been shown to last up to 240 days and transmission is very slow. One pig needs 4 to 6 weeks to transmit the disease to another pig versus the flu that is transmitted from one pig to 14 others in a 2-week period.

Elimination starts on sow farm

Current elimination programs have successfully removed M. hyo from many herds. But the methods for elimination continue to improve by focusing on gilt acclimatization and sow farm stability.

“We need to think about negative gilts,” Betlach said. “If you have a positive farm and you constantly bring in negative gilts, you are adding wood to that fire. Therefore, we need to think of ways to address this.

“Gilt acclimatization is something we should think about,” she continued. “Gilt acclimatization strategies are designed to stabilize the sow herd by promoting ways to minimize shedding at farrowing.”

Acclimatizing gilts

Three types of gilt acclimatization are used, namely vaccination, natural exposure and exposure using a herd-specific lung homogenate. Vaccination for M. hyo is commonly practiced as it can reduce the bacterial load and clinical severity. However, M. hyo vaccination does not prevent colonization and has minimal effect on altering transmission.

Natural exposure through the introduction of M. hyo-positive culls into a gilt development unit has been performed. However, this approach is less than ideal in larger herds, as it takes a long time for adequate exposure and requires a high number of positive culls. Studies have shown that it takes one positive cull to one or two gilts for successful exposure within a 4-week period.

Exposure using a herd-specific, M. hyo-positive lung homogenate has been performed in the field, via intra-tracheal or aerosol techniques. Intra-tracheal exposure is a more labor-intensive method and may not be as feasible in large populations, as approximately 50% to 70% of the herd will need to be exposed to be successful. Therefore, aerosol exposure using foggers has been explored. Recently, this method has been shown to be successful for M. hyo exposure while being more feasible to perform.

Diagnostics for M. hyo

Several sample types are used for the detection of M. hyo. It is important to consider the overall goal that you are trying to achieve, as this will determine what sampling method should be used.

“Serum is commonly used, and the cost is relatively low,” Betlach said. “This sample type is used to detect the presence of M. hyo antibodies and it is easy to collect. However, the ability to interpret diagnostic results can be difficult, especially in vaccinated herds as the presence of antibodies from the vaccine or infection cannot be differentiated.”

Other sample types, such as oral fluids, laryngeal swabs and tracheal sample, are used to detect the presence of M. hyo infection. Oral fluid samples are easy to take, and the results are easy to interpret, in most conditions. Oral fluid samples work best in chronic situations but are not sensitive enough to detect the pathogen in an acute infection.

Laryngeal swabs, which are convenient, require some employee training. Positives can be obtained at 7 to 14 days after infection, Betlach said. In comparison, tracheal samples appear to be more sensitive in acute and chronic situations. This sample type also requires additional training as false-negative results from poor sampling technique can occur. Due to their sensitivity, Betlach uses tracheal samples in elimination strategies.

“Diagnostics have improved over the years,” she added. “For M. hyo detection, it is critical to think about what sample type you are going to use and the time of infection, and to understand the question you want to answer.”



What’s the US emergency response to African swine fever?

The emergency response to a possible outbreak of African swine fever (ASF) in the US stands ready for implementation, according to Beth Thompson, DVM, Minnesota state veterinarian and executive director of the Minnesota Board of Animal Health.

Thompson helps plan for potential foreign animal disease (FAD) outbreaks like ASF. She also must help implement plans when an outbreak occurs, like those for the avian influenza (AI) outbreak in 2015.

Thompson laid out the ASF emergency response plans to a group of Swine Vet Center veterinarians and pork producers. These emergency preparations are determined and then practiced during trial runs by the USDA, state boards of animal health and departments of agriculture.

“USDA has had a handful of exercises specific to ASF,” Thompson said. “At least 14 states involved are working through mitigation and response plans.” This fall, USDA will run a full exercise across several days with more than 14 states, covering different parts of the investigation and response process.

Investigate, diagnose

The first step in an emergency response comes when a state veterinarian is notified of a suspected FAD. A specially trained state or federal FAD diagnostician is sent to the site and two sets of samples are taken.  One sample is sent to the University of Minnesota diagnostic lab and the other is flown to the federal diagnostic lab at Plum Island on the East Coast or to a new USDA lab in Manhattan, Kansas, that will open soon.

After collecting samples, FAD diagnosticians begin gathering information from veterinarians and staff about movement onto and off the property including vehicle traffic, biosecurity, employee travel, etc. for the disease investigation.

The university will send preliminary test results back first, but nothing can be made public until the federal lab makes a confirmation and releases the official results, which can be 12 to 15 hours later.

False positives are extremely rare. During the AI outbreak, the university diagnostic lab tested 16,000 samples with zero false positives.

72-hour standstill

At the point of ASF confirmation, the USDA can initiate a temporary state, regional or national 72-hour standstill to all pig movement. Trucks hauling pigs should get to where they are headed and stay put.

“Then we try to figure out what is going on,” Thompson explained. “We’ve got a whole assortment of ways that ASF can be moving around. We have to look at feed mills, animal movement, and so on.”

The standstill may also include feed trucks, depending on individual states. States also may decide not to impose the 72-hour standstill in certain circumstances.

Depending on what is discovered during the standstill, plans for control zones, depopulation and disposal will be determined and put into action.

“To give you an idea of how this works logistically, during AI, I was part of the first initial response found in Polk County in late February 2015,” Thompson explained. “We went to Willmar on Thursday and quarantined the property. We got depopulation going and did surveys around a 10-km control zone (from the outbreak site). We went home on Sunday and thought we were all done. A few weeks later there were more cases.”

The response to the AI outbreak ballooned with cases erupting around the state. “In one day, we had 520 people working just on the response,” she added.

Thompson’s team is able to quickly ramp up when an emergency occurs. “The Minnesota Board of Animal Health has 44 employees. But the state department of ag has 400 employees, and we can also draw from additional resources within the state up to the National Guard,” she said.

Thompson also works with county and local officials to get more feet on the ground where outbreaks occur.

Backyard pigs, garbage feeding

In addition to being prepared for an outbreak, Thompson said the board is working on education with pork producers of all sizes and types.

“We’ve got a large population of people who raise one or two hogs in their backyard for personal use so there’s a lot of education that our agency can get involved in,” she explained.

Minnesota also has a statute that allows permitted garbage feeding but with strict controls, including monthly inspections of the cooking equipment and trucks. Permits have been granted for two classes of feeders; Class A can feed food waste that contains or has been exposed to meat, and Class B can only feed food that’s never had contact with meat. ASF concerns are mostly tied to the Class A holders who generally service grocery stores and restaurants in the Twin Cities.

“I know there’s a lot of interest in this because of possible ASF transmission in meat,” Thompson said. “I support permitted garbage feeding because I know we can achieve a lot more for animal health through cooperation and collaboration than an outright ban of the practice.”

She added that the permit holders are well versed on safe garbage-feeding rules and have visited pork producer meetings to discuss their cooking processes.

Industry involvement

While the state board of animal health will head up the response to an ASF outbreak, Thompson stresses that the entire industry must be involved to make an emergency response successful.

“What keeps me up at night — the amount of damage ASF can do to this commodity group is astounding,” she added. “Not only what would happen with this commodity group but with the related corn and soybean groups if we got ASF. The effects would be devastating.”


Maintain sound on-farm biosecurity with PRRS ‘season’ approaching

By Brad Leuwerke, DVM, MS

As we creep closer to autumn’s weather change, crop harvest, manure pumping, etc., we also sneak closer to what has become a predictable rise in new cases of porcine reproductive and respiratory syndrome virus (PRRSv) across the country.

For 10 years now, the Dr. Bob Morrison Swine Health Monitoring Project has shown that the swine industry experiences an annual rise in PRRSv cases over an epidemic threshold in the October to November time frame. If history has anything to say, a similar trend should be expected this fall.

Knowing that one of the biggest drivers of profitability for swine producers is reducing nursery and finishing mortality and culls, those swine producers who are able to keep PRRSv out of their herds will have an economic advantage.

As fall arrives and the number of PRRSv cases begins to rise, swine veterinarians will start to get a sense of whether there are any new or more pathogenic “strains” that may become the new virus to be on the lookout for as an industry.

The last two to three years have given rise to PRRSv 1-7-4 and 1-3-4; both viruses caused severe disease in sow herds, leading to aborted fetuses, piglet mortality and sow mortality.

The other challenge these viruses have presented is the difficulty in eliminating them from sow farms. The “traditional” 210- to 240-day closures designed to eliminate PRRSv from a breed-to-wean farm have not been as successful, forcing many producers to make a decision on whether to keep a herd closed longer in hopes of eliminating the virus or to reload the farm and restart the elimination procedures over again in an effort to not miss production targets.

Research on these viruses and how they are transmitted within a herd has shown that these newer strains are shed for a longer period and are shed in higher amounts from infected animals. There also is speculation that new viruses are able to change more quickly within a population. All of these factors have worked to decrease the success of PRRSv elimination in breed-to-wean herds.

The effects of an increasingly pathogenic virus also can be seen in growing pigs. PRRSv 1-7-4 and 1-3-4 infection in growing pigs continues to be severe, causing greater mortality with higher culling rates and increased treatment costs compared to PRRSv strains observed in the past.

Similar to the observations in sow farms regarding the timing of disease, the effects of PRRSv infection seem to extend to longer periods compared to past PRRSv strains. Nursery and finishing sites that are continuous flow struggle tremendously to eliminate the virus and should consider all-in/all-out or, at the very least, site depopulation to eliminate virus from these populations of growing pigs.


The cornerstone of preventing new virus introduction still relies on biosecurity, biosecurity, biosecurity.

Even though newer strains of PRRSv act increasingly pathogenic, sound biosecurity practices — including clean/ dirty lines for site entry, controlled supply entry, organized (clean to dirty) personal movement, dedicated trailers, mortality composting, etc. — help limit virus spread from farm to farm.

Air filtration of breed-to-wean farms continues to be successful. Filtration hasn’t been 100% effective in all cases, but when looking at dense areas where sow herds were breaking multiple times each year, the reduction in the outbreak rate has been extraordinary. Updated technologies, including positive-pressure filtration systems and air conditioning, which reduces the amount of air that needs to come into the barn, continue to move the bar on what can be expected for preventing virus introduction into these farms.

A PRRSv vaccine remains an important tool available to producers for virus control. Recent additions of modified live PRRS vaccines on the market give swine producers further options for vaccines.

In many commercial sow herds, especially those in more densely populated swine areas, a modified live vaccine is used to help maintain immunity at least with the goal of lessening the impact a new virus introduction will have on the herd. In many of these cases, the herds and replacement gilts are vaccinated multiple times each year to maintain immunity.

In growing pigs, millions of pigs continue to be vaccinated for PRRSv (either prior to weaning or at some point while in the nursery). PRRSv vaccines continue to show the ability to reduce lung lesions for pigs that become infected with a non-vaccine strain of the virus. In addition, groups that are vaccinated and exposed to a field virus consistently show closeouts that have less mortality and a lower cull rate compared to nonvaccinated groups that become infected with field strains.

As an industry, we’ll start to see the benefits of new diagnostic technologies, including whole-genome sequencing, which will provide more insight than ever before regarding PRRS circulation and change within a population. Take, for example, herds that are unsuccessful at eliminating a resident PRRSv strain from their herd. Whole-genome sequencing will help determine if that virus continues to be the resident strain or if a completely new virus strain has been introduced into the herd.

It goes without saying that it has been and will continue to be an interesting time for all swine producers. The industry is already starting to make market pigs for June 2020. It’s paramount to keep PRRSv out of the herd. Those producers who are able to limit new virus entry will have a greater opportunity to keep reducing pig mortality and culls, leading to increased profitability.

PRRSv “season” will be here soon, so it’s important to emphasize that the biosecurity practices producers have used for years for PRRSv and other pathogens still apply.

Reprinted with permission of Feedstuffs.

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Is fogging an M. hyo-elimination option for your swine herd?

Paul Yeske, DVM, with the Swine Vet Center in St. Peter, Minn., has seen repeatable success with Mycoplasma hyopneumoniae (M. hyo) elimination, along with the downstream effect of lower cost of production, better average daily gain, better feed efficiency and lower mortality. He estimates the benefit of M. hyo elimination to be in the $3 to $4 range per pig, conservatively, with some herds seeing a benefit of as much as $10 per pig when other diseases are eliminated at the same time. Now, the relatively new protocol of fogging a barn may make M. hyo elimination even more attractive.

This technology came out of the frustration of trying to evenly and efficiently expose animals to the bacterium, Yeske told Pig Health Today. Fogging allows for faster exposure to establish “time zero” for elimination, so gilts can be stable by the time they enter the sow herd.

“That reduction of time for M. hyo to spread from animal to animal in a natural way is probably the biggest advantage,” he said. Previously, Yeske would use intratracheal exposure of seeder animals, but said, “It’s a lot of work and you still have slow spread from animal to animal. Fogging has been very successful for us, although it’s still new technology and there are some lessons to learn as we go forward.”

Research needed

Fogging appears to be an effective method for M. hyo elimination, but Yeske said critical questions need to be answered on the technology:

  • How long can the inoculums be stored?
  • How long can the lungs used for the inoculum be stored if the herd is kept positive?
  • What’s the best media to use for exposure?
  • Should an M. hyo media be used, or can we use phosphate buffered saline?
  • Which products work best for fogging in terms of storage and/or the fogging procedure?
  • What’s the right dosage and volume level?

“So far it’s been very good, even with the experimental method we’ve used, but I think there’s an opportunity for it to be better,” Yeske said, adding that, “We just need to support the researchers to do the difficult work to answer these questions.”

Other methods also effective

Yeske said depopulation/repopulation is the “tried and true” method that works every time but it’s also the most expensive. It’s difficult for people to invest the money unless there are other compelling reasons, such as additional disease challenges or parity re-distribution, he noted.

The herd closure model is to keep a herd closed (no new introductions) beyond 240 days, Yeske said. Hee recommends medicating the sow herd and piglets at the end of the closure, which allowed the pigs’ immune systems to help as much as possible. Timing varies, but this model has been the most successful and has had the least amount of impact on production.

“We’ve been in the 75% to 80% success rate over time and it’s been the most repeatable system,” he said. “Generally, mycoplasma elimination has been done in conjunction with other diseases, such as porcine reproductive and respiratory syndrome (PRRS). It just adds a little more time to standard PRRS-closure and you also get rid of the M. hyo,” he said.

Another method involves whole-herd medication, without a herd closure, but Yeske said the success rate is closer to 50% when medication is done without herd closure.

“If we do limited-herd closure (150-240 days) and then medicate at the end, the process has been more successful and closer to the long-term closure success rates,” he said.

Useful tool for control or elimination

Fogging may not be a silver bullet, but Yeske said it’s a useful tool for M. hyo control, “whether you’re doing ongoing control and acclimating replacements into the herd, or you’re looking at elimination. The technology is fairly inexpensive, so it’s about having your herd veterinarian help set up the program to make sure you’re doing everything the right way.”

Yeske is often asked how likely a herd is to stay negative if a producer goes through the Mycoplasma-elimination process, especially in pig-dense areas.

“We did some research two years ago and found that lateral introductions happen, but they are rare,” Yeske said. “We saw 94% of the herds stay negative, even in pig-dense areas.”

He recommended producers and veterinarians work on herd stabilization, with consideration given to elimination if other issues are impacting the herd.