Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: December 10, 2001
Publication Date: N/A
Respiratory disease in pigs is one of the most important health concern for swine producers today. The term "porcine respiratory disease complex" (PRDC) is used to describe pneumonia of multiple etiology causing clinical disease and failure to gain weight. The etiology of PRDC varies between and within production systems and is the result of a combination of primary yand opportunistic infectious agents and adverse environmental and management conditions. It is common to categorize pathogens as either primary pathogens, capable of subverting defense mechanisms and establishing infection on their own, or opportunistic pathogens, which take advantage of the virulence mechanisms of the primary pathogens to establish infections. Primary agents in pigs include viral agents such as porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), pseudorabies virus (PRV), and possibly porcine respiratory coronavirus (PRCV) and porcine circovirus type 2 (PCV2); and bacterial agents like Mycoplasma hyopneumoniae, Bordetella bronchiseptica, and Actinobacillus pleuropneumoniae. The most common opportunistic agent is Pasteurella multocida, but other common opportunistic agents include Haemophilus parasuis, Streptococcus suis, and Actinobacillus suis. Non- infectious causes (management and environmental factors) are significant contributors to respiratory disease, either by increasing transmission and spread of the pathogens or by creating unfavorable conditions which result in increased stress for the animal or damage to the respiratory tract.