Properly prepare gilts to match farm’s Mycoplasma status

After living with Mycoplasma hyopneumoniae (M. hyo) for years, producers now know that maintaining a stable M. hyo status is key to reducing the disease’s impact.

“The more we know about M. hyo, the more we realize how important it is to have a gilt properly prepared for either a negative or a positive farm and not mix those statuses,” said Cary Sexton, DVM, Four Star Veterinary Service in Kinston, North Carolina.

Synchronize M. hyo status

“First, you need to understand the status of the sow farm the gilts are going to,” Sexton said. “Then, the gilts need to be properly prepared, either exposed and vaccinated or both if going to a positive farm or kept clean if going to a negative farm. I would recommend working with your veterinarian to determine the proper sow-farm status.”

Most commercially available genetic stock now has a negative status, he explained. Any sow farm with a different M. hyo status will need a plan to synchronize health of the gilts before they are mixed with the herd.

“There are multiple ways to synchronize, but it has to be some type of exposure,” Sexton said. “Exposure should be at weights around 40 pounds to make sure it’s long enough for the animals to get through an infection and clear the active shedding phase. If you put shedding gilts into a stable-positive farm, it could turn clinical.”

The most common exposure methods are direct inoculation with a live M. hyo culture or fogging with lung homogenate material.

“Direct inoculation is the most labor intensive,” he said. “You have to catch each animal and inoculate it. In a barn with 1,000 gilts, it is a full day of work versus fogging that only takes a couple of hours after the environment is readied for the procedure. The most difficult part is getting exposure done consistently on an every-group basis.”

Mounting immune response

After exposure, gilts must be closely monitored for illness, including secondary infections.

Animals sickened by exposure need to be treated to help them recover and to ensure the infection doesn’t become chronic, Sexton explained.

“You want them to get exposure and mount an immune response while continuing to grow. Ultimately, they will stop shedding or shed at a very low level by the time they are ready to move onto the sow farm,” he said.

Because M hyo is a very slow-growing pathogen, it may take 7 months to complete this process. Producers must plan for adequate time and space to handle gilts for these extended periods. This time lapse increases with natural exposure as each new exposure results in resetting the time clock.

Eliminating M. hyo

Interest in M. hyo elimination is growing as producers learn about its benefits. A negative herd could see a $5-to-$7-per-market-hog improvement from when it was M. hyo positive, particularly in the growing-pig segment of production.

Two types of operations are more interested in eliminations, according to Sexton. A farrow-to-finish farm will recoup the most benefits by owning hogs to market, while a farrow-to-wean operation sees a benefit in the health of weaned pigs sold to customers.

Improvements in testing methods for M. hyo also help make eliminations successful. Deep-tracheal swabs examined by polymerase chain reaction are reliable and repeatable, he added.

If an operator is considering an elimination program or wants a change in the M. hyo status, Sexton recommends first determining the herd’s status. Then he or she should meet with a veterinarian to discuss options for the farm.

“Have a conversation about wanting to make a change in M. hyo status or looking for a different source of genetics,” he said. “You need to [identify] the cost-benefit ratio of each option. Is it worth the time and money to do an elimination? Or is there a way to get exposure of these animals to produce a stable-positive farm? You may be surprised which one rises to the top.”


Managing Mycoplasma’s persistence in finishing

A dry cough heard in a finishing unit usually indicates Mycoplasma hyopneumoniae (M. hyo) is causing respiratory distress and reducing growth in pigs almost ready for market.

“We’ve been seeing M. hyo in finishing where it pops up in mid- to late-finishers,” reported Bryant Chapman, DVM, Four Star Veterinary Service (FSVS). “It decreases feed intake and potentially causes mortality, especially if it has a secondary disease with it as well.”

Working from the FSVS clinic in Chickasaw, Ohio, Chapman helps clients reduce the effects M. hyo can exert on a farm if left unchecked. The cost of finishing pigs infected with M. hyo is estimated at $3 to $5 per head more than pigs without the disease.

Immediate response

“Mycoplasma is a slow-moving bug and is slow to show itself, which is why we see it in finishing,” he explained. “Clients will call and say ‘I have healthy-looking finishing pigs, but they have this dry, non-productive cough.’

“Depending on when the hogs will be marketed, we rely on antibiotics. Feed-grade and water-grade medications given over a period of time do fairly well to decrease the symptoms at the finishing level. And we do follow-up with injectables on a few animals needing it.”

Because M. hyo is a respiratory pathogen, dusty conditions and poor ventilation will exacerbate the symptoms. It also appears more in the winter when buildings are closed up.

Seeking the source

“Some farms we work with on finishing, the clinical signs show up at the end stage when they get compounding factors like porcine reproductive and respiratory syndrome (PRRS) or the flu and we find M. hyo via testing,” he added.

To test M. hyo in finishing, Chapman recommends using lung tissue from freshly euthanized pigs rather than oral fluids from live pigs, which is a less sensitive test.

Typically, the source for an M. hyo outbreak is at the sow farm. Sometimes, the outbreak in finishing is the first indication that a sow unit may be infected with M. hyo, especially if the sow unit went through an elimination for the disease. Tracheal or laryngeal swabs for testing verify the disease outbreak.

Depending on the severity of the outbreak and the herd’s health status, sow farms may work out a control program with their veterinarian to use vaccinations and exposures. Or they may decide to undergo an elimination of M. hyo.

Pros, cons of elimination

“Many farms choosing to go through an M. hyo elimination have either been exposed to or associated with PRRS,” Chapman said. “If they are going to do a PRRS elimination, they will just go that extra length of time to eliminate mycoplasma.”

Eliminating two diseases at once is a positive, but the time needed to eliminate both is 8 to 9 months.

A successful elimination is also helped by the farm setup. “If you have the availability and resources to stock enough females for a closure, or you can have off-site breeding facilities for a closure, it might be feasible,” he explained. “But if you have to completely shut down females for 8 or 9 months without any prep for a pause in production, that would be pretty painful for a farm.”

Hog farms have used different methods to eliminate M. hyo and other disease from their herds. Generally, all methods are costly, and the level of success is 50% to 80%, Chapman said.

Some farms have been able to keep M. hyo out of the system. He works with a few farms that are negative and have not found it in their finishers.

In the end, producers dealing with M. hyo will need to decide based on a cost/benefit analysis what path will be best to handle the pathogen in their own unit, he added.


Check with your Four Star veterinarian to determine the best steps forward following a mycoplasma outbreak on your farm.