Porcine Respiratory Disease Complex (PRDC)

The vast majority of respiratory problems in swine are due to a combination of disease pathogens called PRDC, involving a mix of viral and bacterial pathogens. Signs of swine respiratory disease include coughing, sneezing, fever, labored breathing, nasal discharge, lethargy, and pigs that are off-feed.

Bacteria often involved in PRDC include Pasteurella multocida, Mycoplasma hyopneumoniae, Streptococcus suis, Haemophilus parasuis, Actinobacillus pleuropneumoniae, and Salmonella choleraesuis. Common viral components of PRDC include porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), pseudorabies virus (PRV), porcine circovirus type 2 (PCV-2), and porcine respiratory corona virus (PRCV).

By themselves, most bacterial infections are not that difficult to control, but a combination of these bacterial and viral pathogens in an intense management system often presents a serious and costly health challenge.

Pasteurella pneumonia is caused by the infection of the lungs with Pasteurella multocida. These common gram-negative bacteria colonize the mucus secretions of the respiratory tract of pigs, especially nasal mucus. P. multocida is not a primary agent of swine pneumonia, yet it is the most common bacteria isolated from pneumonic lungs, particularly in market-weight pigs.

Because P. multocida can often be found in nasal and tonsil swabs of healthy animals, strains likely differ in virulence, with less virulent strains common among healthy animals but the more virulent strains producing diseased herds. Nose-to-nose contact between pigs is the most common means of transmission.

Common signs of Pasteurella pneumonia include coughing, thumping (sudden abdominal contractions), labored breathing, and fever. However, subacute infections are more common, characterized by coughing in grower/finisher pigs. The chronic form is actually most common, helping allow Mycoplasma organisms to flourish, resulting in mycoplasmal pneumonia.

The best control strategy for Pasteurella pathogens is prevention because antibiotics tend to be more effective when used as preventatives rather than as therapeutics. Antibiotics used for Pasteurella control must achieve adequate concentrations in lung tissues of treated pigs. Alpharma’s line of chlortetracycline-based feed-grade antimicrobials (Aureomycin®, Aureo S-P 250®, AureoZol®, and ChlorMax®) provide effective, easy-to-administer Pasteurella control for the entire herd, delivering much higher lung levels of drug compared to oxytetracycline-based feed-grade products.