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Fogging helps establish Day 0 for M. hyo elimination

The company’s commitment to Mycoplasma hyopneumoniae (M. hyo) elimination is an important component of the equation, and fogging (aerosolised exposure) has been a useful tool in the process.

8 December 2019, at 2:00pm

Maintaining a healthy herd takes time, energy and constant emphasis on biosecurity, Amy Maschhoff, DVM, told Pig Health Today. She oversees the health of The Maschhoffs’ technical operations, which include the company’s genetic and research herds and their downstream flow. She searches for ways to improve herd health, not only at the farm level but for the entire system.

“Our system has eliminated mycoplasma in all of our genetic herds, so I help maintain that negative status,” she said. “We also utilize a health assurance program to monitor those herds for our internal and external customers, to verify the health status we have established and provide what we believe is the best diagnostic evidence available.”

Fogging helps establish Day 0

Maschhoff admits their operation was not the first to think about how to eliminate M. hyo, but she and the health team have spent the last few years refining their procedures on herd closure and elimination. (See the article on M. hyo elimination featuring Melissa Hensch, also with The Maschhoffs, that goes into more detail on the processes.) Elimination methods varied across regions, and as a result, the herd health team identified which methods worked best.

“Our system spent a lot of time trying to determine how to establish Day 0, and we’ve utilized fogging to meet that objective in the last couple of years,” she said. “We didn’t start the clock well on a couple of our closures, so moving forward, we wanted to make sure we established a Day 0.”

Fogging takes the place of intratracheal inoculation, which requires much more labor, is more intrusive and doesn’t guarantee every animal will be exposed to the bacterium unless every animal is inoculated. Veterinary interns led research projects on M. hyo elimination for several consecutive years, and their findings yielded helpful information on fogging procedures and exposure timelines.

The Maschhoffs’ methods

The methods used by The Maschhoffs helped the business become 92 percent negative for M. hyo, with the final remaining herds presently going through elimination programs.

  1. Get the right donor animal: Donor gilts must first be confirmed M. hyo-positive via intratrachael swab. “We will humanely euthanize the animal, and upon necropsy we observe the lungs and look for M. hyo lesions,” Maschhoff said. A portion of the lung is then sent to a lab for diagnostic validation of its M. hyo status. “Typically, a veterinarian is there choosing the sections of the lung to be used for the homogenate. You’re going to see that lung consolidation and reddening color. That is the section of the lung that we’ll choose because it’s highly likely M. hyo is living there. After lab confirmation, we’ll take that section and put it in a blender.”
  2. Make the homogenate: The Maschhoffs often strain the blended lungs, then add an M. hyo-base medium for growth of the bacterium (mollicutes). One research project last summer showed very little difference in effectiveness of media. “A homemade saline solution is the cheapest to make and is just as effective. You can actually take water and salt and make your own saline solution,” Maschhoff said. (An abstract will be presented at the 2020 American Association of Swine Veterinarians meeting.) The homogenate is stored in a commercial media, but a homemade saline solution is used with the homogenate in the fogger. It’s poured into falcon tubes and stored in an ultra-low freezer to maintain the M. hyo. Before use, it’s removed from the freezer and thawed in the same manner as an oral vaccine. A portion is again sent to a lab to confirm the M. hyo is still active before it’s put in the fogger.
  3. Fogging: The goal is to expose every animal to the aerosolized homogenate to establish Day 0 and start the clock on the elimination program. Maschhoff explained that a farm employee actually challenged the health team with the idea to fog the animals rather than performing the intratracheal swabs. He mentioned they fog rooms using disinfectants, so if M. hyo is mucosal, why couldn’t they use an M. hyo homogenate in the same way? Research proved the hypothesis worked. The farm has used different types of foggers with equal success.
  4. Piggyback with elimination of porcine reproductive and respiratory syndrome (PRRS): If a herd breaks with PRRS, it’s smart to consider eliminating M. hyo at the same time PRRS is eliminated, Maschhoff said. Although that wasn’t always the case in every herd, it made sense to eliminate both issues together since the herd was going to be closed for 35 to 40 weeks. However, if just M. hyo is eliminated, The Maschhoffs found the effort was still cost-effective.
  5. Check and double-check: Farms going through an elimination plan have a thorough, dated timeline of what to do at each point during the closure. “We have a template, and then we, as the herd vets within the regions, can take the template and make an outline that’s specific for each farm, so the managers know how and when to execute each step,” Maschhoff said. “There’s a lot of coordination within our system, and we try to explain why each step is important.”

A step forward

M. hyo elimination may not be what the team predicted, and it may not be perfect, but “you can absolutely see a difference in the barn,” Maschhoff said. “You don’t hear that barking cough anymore, and mortality numbers are lower, especially in late-term finishing. That’s a win-win on overall costs and for the people who work in the barns every day.

“The goal isn’t just to make a pig but to make a healthy, cost-efficient pig that has the genetic improvements you want to pass on,” she added.

The health team is looking at what bugs they should tackle next. “We definitely have ideas on how we want to continue to improve the health of our pigs,” Maschhoff said.