Respiratory disease is a big concern in finishing pigs. Respiratory diseases are often more of a concern moving through the changeable weather of fall, the lower ventilation rates of winter and back to the temperature fluctuations of spring.
There are many respiratory organisms that can cause issues. Most are mixed infections with Mycoplasmal pneumonia, viral pathogens and secondary bacterial infections. Mycoplasma is one of the consistent findings in cases of swine respiratory disease and is an infection of the lower respiratory tract (lungs).
Due to prevalence, mycoplasma and circovirus vaccines have become the “must have” antigens for many finishing vaccination programs, with other organisms added to this platform to provide a comprehensive vaccination program.
Case Study No. 1
We were called to a 1,500-sow, farrow-to-finish farm to evaluate a respiratory disease concern. At this three-site operation, farrowing is on one site, the nursery on a second site and finishing on other distant sites. The concern was coughing pigs and a “stall-out” in later finishing. It began with a small number of pigs showing a dry, non-productive cough. Over a two-week time period, this escalated to a 30-40% incidence of cough.
Coughing began around 19 weeks of age. The percentage of pigs coughing in the group decreased near market or approximately four weeks after clinical signs began to heat up.
We drew blood for serological testing and preformed postmortem exams on several pigs. Sera and tissues were submitted for a diagnostic laboratory workup and revealed the pigs were positive for porcine reproductive and respiratory syndrome (PRRS), H3N2 swine influenza virus (SIV) and mycoplasma. The workup showed visible and classic microscopic mycoplasma lesions in the lungs.
From previous laboratory work and lack of findings in the tissues, it was felt that the positive PRRS and SIV serum samples were due to previous infection during the growing phase.
These pigs were being vaccinated at weaning with a one-dose mycoplasma vaccine. The vaccine was changed to a two-dose product and timing was altered to a vaccination at processing and a booster dose at weaning.
The two-dose mycoplasma vaccination program has reduced the coughing syndrome to levels seen earlier in the finishing period. Post-mortem exams improved from 25% pneumonia-like lesions to 10% after the changes. The new program has shown good results across all seasons.
Case Study No. 2
We were called to a 900-sow, farrow-to-finish, single-site farm with a history of respiratory disease in the finisher. This unit was designed with connecting hallways from breeding-gestation through finishing.
A cough was seen around 20 weeks of age as a dry, non-productive cough that began with a few pigs that grew into an outbreak affecting 60% of the finishing group. Postmortem exams were conducted and tissue samples were submitted for lab analysis.
The lungs showed approximately 30% pneumonia in the front, lower areas of the lung. The tissues were positive for PRRS, pasteurella and Mycoplasmal pneumonia, meaning that the active infection included all three pathogens.
A review of the vaccination program showed the pigs were given two doses of a two-dose mycoplasma vaccine at processing and weaning. This would normally be considered a strong mycoplasma control program. As a single-site farm, the concern was the full spectrum of ages receiving increased exposure to all organisms.
Moving the vaccination program to later in the nursery has not been very beneficial. Without changing the existing vaccination program or product, we added a feed-grade antibiotic purge. A purge is the use of a feed or water antibiotic effective against mycoplasma to reduce the growth and numbers of organisms in the pig. The treatment feed was given for 14 days at approximately 16 weeks of age (four weeks prior to clinical signs). Subsequent groups have been completed without the increase in the late-finishing coughing, and lesions on postmortem exams have shown marked improvement.
Respiratory concerns are farm dependent, so getting an accurate herd health diagnosis and developing a specific action plan are important.
Do not rely on a mycoplasma control program that looks good on paper to guarantee success, as some adjustments are often necessary for individual farms. The control of mycoplasma needs to address proper ventilation, antibiotic therapies and the vaccination of pigs. The correct combination of control measures is important to maximize pig health.