Associations between Pleurisy and the Main Bacterial Pathogens of the Porcine Respiratory Diseases Complex (PRDC)

Area of Science:

• Veterinary Medicine
• Animal Pathology
• Molecular Diagnostics

Background:

• Porcine Respiratory Diseases Complex (PRDC) is a significant economic concern in swine production.
• PRDC involves multiple bacterial pathogens, including *Mycoplasma hyopneumoniae*, *Actinobacillus pleuropneumoniae*, *Pasteurella multocida*, *Glaesserella parasuis*, and *Streptococcus suis*.
• Pleurisy lesions caused by PRDC can lead to carcass condemnation, impacting the pork industry.

Purpose of the Study:

• To evaluate the utility of slaughterhouse-based diagnostics for identifying PRDC pathogens.
• To correlate the severity of respiratory lesions with the presence of specific bacterial agents using qPCR.
• To assess the potential of qPCR as a surveillance tool for PRDC.

Main Methods:

• Selection of 1015 pig carcasses from three commercial farms.
• Evaluation of respiratory conditions using the Slaughterhouse Pleurisy Evaluation System (SPES).
• Collection of 106 pleural and lung fragments for quantitative Polymerase Chain Reaction (qPCR) analysis to detect five key bacterial pathogens.

Main Results:

• Moderate correlations were observed between lesion severity and the presence of *Pasteurella multocida* (R=0.38) and *Actinobacillus pleuropneumoniae* (R=0.28) in pleural samples.
• Lung lesion severity showed moderate correlations with *Pasteurella multocida* (R=0.43) and *Mycoplasma hyopneumoniae* (R=0.35).
• A strong correlation (R=0.82) was found between *Pasteurella multocida* and *Mycoplasma hyopneumoniae* in pleural tissues.

Conclusions:

• qPCR is a valuable tool for identifying and quantifying PRDC causative agents in field surveillance.
• The study highlights the complex interplay between bacterial pathogens and lesion development in PRDC.
• Slaughterhouse diagnostics combined with molecular methods can provide comprehensive insights into PRDC prevalence and impact.