Abstract
Abstract Porcine respiratory disease complex comprises the interaction of two or more infectious agents. The major bacterial agents involved were investigated in 115 finishing pigs at a farm in São Paulo State, Brazil: Actinobacillus pleuropneumoniae (serology, bacterial culture, and multiplex PCR), Mycoplasma hyopneumoniae (Mhyo) (nested PCR), Pasteurella multocida (multiplex PCR), Haemophilus parasuis (PCR multiplex), and Streptococcus sp. (bacterial culture). Macroscopic and microscopic lung lesions were evaluated, and zootechnical indices were recorded. Mhyo occurred in 113 animals (98.3%), seventeen of which were co-infected with Streptococcus sp. The finding of emphysematous lung was associated with significantly lower final and carcass weight at slaughter. Although vaccinated against Mhyo with an inactivated immunogen, almost 100% of the animals were infected. Mhyo infection with and without Streptococcus sp. co-infection was related to lung lesions of varying degrees and lower slaughter and carcass weight.
Highlights
Respiratory diseases are a critical issue in intensive pig rearing[1]
The major bacterial agents involved were investigated in 115 finishing pigs at a farm in São Paulo State, Brazil: Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae (Mhyo), Pasteurella multocida, Haemophilus parasuis (PCR multiplex), and Streptococcus sp
Pneumonias result in low zootechnical indices, high pharmaceutical costs, and carcass condemnations at the slaughterhouse, where, in Brazil, approximately 50% of animals present some type of lung injury, with these lesions accounting for 50% of all carcass condemnations[3]
Summary
Respiratory diseases are a critical issue in intensive pig rearing[1]. Confined populations are subjected to an environment that may be stressful and reduce immunity, contributing to the occurrence of respiratory disease[2]. The etiology of respiratory problems in pigs is complex, usually involving interaction of two or more infectious agents[5], bacterial and/or viral, in addition to factors such as handling and environment, affecting pigs in the growth stages and their value at slaughter[6, 7]. Porcine respiratory disease complex (PRDC) describes a syndrome that encompasses several bacterial agents, including Mycoplasma hyopneumoniae (Mhyo), the agent of enzootic pneumonia in swine; Pasteurella multocida, responsible for pleurites and which, together with Bordetella bronchiseptica, causes atrophic rhinitis; Actinobacillus pleuropneumoniae, causing swine pleuropneumonia; Haemophilus parasuis, the agent of Glasser's disease; and Streptococcus suis, causing pneumonia and pleuritis[7]
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