Mycoplasma control starts with stabilising sow herd

Stabilising a sow herd requires a programme that minimises shedding in gilts at the time they farrow.

19 March 2019, at 12:00am

Economic losses caused by the bacterium Mycoplasma hyopneumoniae run between $3 to $10 per finishing hog due to reduced pig performance, according to Elise Toohill, DVM, Carthage Veterinary Service.

“You get closer to $10 a pig if you have an extremely unstable sow herd or if you have other viruses associated with your pigs like PRRS (porcine reproductive and respiratory syndrome) and influenza,” she added. in conversation with Pig Health Today.

Mycoplasma can sometimes be managed effectively with vaccines, feed medications and injectable antibiotics. More recently, some producers and veterinarians have teamed up to eliminate the disease altogether - a costly initiative but one that can yield a high return on investment when maintained.

But in the end, no Mycoplasma-management tool or protocol is perfect. “Even elimination, while it works, is very costly and difficult to get done,” she said.

Stabilise the sow herd

Toohill suggests using another control method to enhance other control options. “Stabilising your sow herd will not only help clinical signs but will also help all control methods be more effective,” she said.

Stabilising a sow herd requires a program that minimises shedding in gilts at the time they farrow.

“Unlike some viruses, the piglets cannot be infected by Mycoplasma in utero,” Toohill explained. “They are exposed in the farrowing crate by shedding sows and gilts.”

Once infected, animals stay positive for up to 254 days from time of infection.

“(You) have to get gilts exposed 254 days before they farrow to minimise the likelihood that your weaned pigs will be positive,” she said. “When we do the maths, the gilts must be exposed by 80 days of age.”

Exposing young gilts to Mycoplasma

Ironically, exposing gilts to Mycoplasma can be difficult, even using live-animal acclimation. Mycoplasmais spread through nose-to-nose contact with a high positive-animal to negative-animal ratio. Toohill said six positive animals are needed to make one negative animal become positive.

“That’s why over the last few years we try to inoculate animals directly, because we know how many animals are truly positive and how they got positive,” she said.

Using a homogenate made from Mycoplasma-positive lungs, Toohill has tried intratracheal and aerosol inoculation.

“Intratracheal inoculation is quite labour extensive and takes several minutes for every animal,” she explained. The process requires three people to hold the pig and send the inoculate into the gilt’s airway and lungs.

Inoculating by aerosol

“A new method we’ve used over the last year is aerosol inoculation,” Toohill said. The homogenate is aerosolised into the air around the gilts. They use a tarp to reduce the air space so the “fog” remains around the gilts for 30 to 60 minutes.

“You can get more animals exposed a lot quicker, and it seems to be a more uniform and natural exposure,” she added.

Mycoplasma is an expensive disease and there is definitely value to stabilise or eliminate it,” Toohill concluded. “(It is a way to end) the vicious cycle of challenging your herd with Mycoplasma. Piglets are exposed in the farrowing house and that determines the clinical signs at finishing or at selection for multiplication.”