Recently, the respiratory diseases of swine have managed to emerge as a significant economic problem and present a substantial challenge to both veterinarians and producers. The porcine respiratory disease complex is most often due to the interaction of multi-factorial etiologies. The purpose of this study is to investigate important etiologic agents associated with porcine respiratory diseases and to provide control strategies for such diseases. We propose applying clinical pathology, histopathology, microbiology, and epidemiology methods to diagnose the porcine diseases and useful preventive approaches will be hopefully provided. The result of this study could improve the diagnostic abilities and strengthen the prevention network for the sustainable operation of animal production industry.