According to Pig333, a pig veterinary resource, a sudden outbreak of coughing among a herd of pigs could signify a problem in their living environment or more seriously, an infection. In piglets, coughing is considered a sign of failure to thrive, while in adult pigs coughing may be an indicator of an underlying condition. It is important to address the pig's health immediately to catch any illnesses in the early stages.
According to Pig333, a contagious and infectious pathogen may have entered the pig's environment, causing it to cough. The most common bacterial pathogens that can cause coughing in pigs are streptococcus, bordatella, haemophilus, pasturella and actinobacillus. Mycoplasmas, bacterial parasites, are pathogens that can also cause coughing, as are viruses. The most common viruses that cause coughing in pigs are swine flu, porcine reproductive and respiratory syndrome (PRRS) and porcine circovirus type 2 (PCV2).
Strongyloides ransomi, an internal parasite commonly known as threadworm, can cause coughing in pigs. According to The Pig Site, a pig industry news organisation, the parasites are uncommon among weaned, growing and fully grown pigs, but do pose a threat to sows and piglets. Iowa State University's College of Veterinary Medicine states that threadworm larvae can attack a host by penetrating the skin or by being ingested in feed. In piglets, the worm is transmitted in colostrum when nursing or even when the piglet is in the womb on an infected sow. Checking the pig's faeces for threadworm larvae and removing all faeces from the pig's living quarters within four days is a preventive measure for controlling threadworm infection.
According to the North Carolina Swine Veterinary Group, a dry, nonproductive cough is the first symptom of mycoplasmal pneumonia in pigs. Mycoplasmal pneumonia is caused by the organisms Myscoplasma hyopneumonia and Pasturella multocida, which are typically found in the pig's lungs. Mycoplasmal pneumonia usually does not cause death unless the pig has an additional health condition, and it can be treated with antimicrobial medication in feed. Vaccinations are also recommended as a preventive measure.