Becca Riggs, DVM with Four Star Veterinary Service in Rushville, Indiana, had this experience recently with what turned out to be an unusual presentation of Mycoplasma hyopneumoniae. Dr. Riggs recently spoke to explain the clinical signs she did see, the path to solving the disease case and lessons learned from the experience.
Dr. Riggs, what does Mycoplasma hyopneumoniae normally look like?
We typically see Mycoplasma in the mid to late finishing stage. Infected pigs usually have a non-productive cough which is a little different than an influenza cough. The pigs are also thumping or trying to breathe really hard and are a little lethargic. As they progress through finishing, you will start to visibly see decreasing growth rates, resulting in weight variation in the groups. Fevers are typically mild at 103°F (39°C).
How quickly does Mycoplasma spread? Do you expect a few sick pigs or a sick barn?
It’s more of a sick barn scenario, but it’s doesn’t move through the barn as fast as other viruses like an influenza or PRRS. I’d expect to see a few infected pigs in every pen that are coughing. Or if not coughing, they are standing and have an increase in respiratory effort.
How do you treat pigs in an outbreak?
When we identify sick pigs, there is antibiotic treatment available either through a medicated water system or an individual injectable treatment which may provide faster response to pigs that are really sick.
Pigs would normally be vaccinated early in life and the mother would have received a vaccine typically prebreeding, so the piglets would gain some built-in immunity when born. However, breakthrough infections can occur – sometimes a herd will get unstable and break, or a naïve sow farm might have pop-up infections, or replacement gilts come in and transmit the disease to the herd, or humans may walk it onto a farm.
Ultimately, we get an unstable situation, plus the vaccine immunity may have faded. I think that’s why we see Mycoplasma pop up more often downstream in mid to late finishing. If we can keep the sow farm healthy – either negative or very stable after we break – then we typically don’t have issues downstream. Economically speaking, when you have Mycoplasma in the sow farm, until you stabilize your sow farm, you’re going to have losses in every group of pigs downstream.
Case study: It started with abortions
In late December I received the first call from our client, and they just had four late-term sows abort their litters, which is atypical for their herd. The sows only went off feed while they were aborting then seemed to recover quickly. The sows that had aborted went right back on feed, didn’t have fevers and clinically seemed normal.
While at the farm, a sow was in the process of aborting, and she had a fever of 106°F (41°C) which is a little higher than what we expect for a bacterial infection.
At that point, I was leaning more toward a virus like porcine respiratory and reproductive syndrome (PRRS) or influenza. In the farrowing house, we started seeing more stillbirths than usual and a lot more weak pigs in those litters. Seeing both still led me to a PRRS outbreak as it’s not uncommon to see those clinical signs with PRRS.
Testing and treatment
Next, I took nasal swabs from the sow that had the 106°F fever and another from a sow that had recently aborted. Given the clinical signs, I felt pretty confident that the results were going to be PRRS positive or perhaps influenza.
While we were waiting on the results, we implemented a Tulathromycin antibiotic treatment in the weak pigs in farrowing. We gave the sows aspirin in the water, and we already had Tilmicosin in the feed for the sows in lactation, so we kept on that path until we had the diagnostic results.
To my surprise, the PCR results for PRRS and influenza both came back negative.
Then the farm had six more abortions. So, we ran antibiotic medication in the water in lactation. The strange thing was the older pigs getting ready to wean seemed almost unaffected. Our newest litters had weak pigs, but it didn’t seem like we were getting much crossover into the pigs that were getting ready to wean. I would expect to see issues throughout the farm, because production is all right at the sow farm.
Since we didn’t have a water medicator in gestation, we did a mass Tulathromycin injection to all the sows, including incoming gilts.
Next, we took samples from the aborted fetuses and tested for PRRS, parvovirus, Porcine circovirus type 2 (PCV2) and PCV3. They all came back negative. So, I was racking my brain trying to figure out why we were having all these abortions.
After implementing the medications, things did seem to improve slightly, but we just weren’t back to where we needed to be by any means. We weren’t having quite as many abortions in a steady manner, but we were still having more than we needed for each of the groups coming up.
A new clue
Then we started to see some increased death loss and fevers in the finishers. Since they have some finishers onsite, this new clue started to point us in a different direction.
Next, we necropsied a few finisher pigs and took blood and tissue samples, and it looked like Mycoplasma. We tested the samples for Mycoplasma, PRRS and PCV using PCR and ELISA to determine their antibody levels. The diagnostics came back positive for Mycoplasma.
The next step was to mass vaccinate the sow farm with a Mycoplasma vaccine. PCV was stable, so a combination vaccine wasn’t necessary. After the vaccination, the abortions stopped. We had fewer stillbirths, pig quality improved, litter numbers improved, and farrowing improved as well.
What lessons were learned?
A situation like this can be difficult and frustrating, but in the end when you finally find an answer, it’s important to look back at what you learned from the experience so you can apply it to future disease challenges. My suggestions:
Keep an open mind. Even though a disease might look like something you’ve seen 100 times before and maybe you’re 99% confident with your diagnosis, don’t forget about all the diseases it MIGHT be. It’s important to cast a wide net at the start of an outbreak. Try not to get so zeroed in a specific diagnosis at the beginning because, like with this case, it might be a disease presenting itself differently than anything you’ve seen in the past.
Collaborate. I also collaborated with other veterinarians at Four Star throughout the process. It’s really important to brainstorm ideas, options and treatments with your boss and/or colleagues because their experience in the field can make all the difference. It just takes one suggestion to spark an idea that can help you think about a problem differently.
Monitor. Even though we are back to normal at the farm, we are monitoring our vaccination response and are prepared to go back with a booster if needed every six to 12 months to maintain stability. Outbreaks often remind us how important ongoing diagnostic disease surveillance is.
