Examination of lung lesions at the slaughterhouse is a useful tool to estimate the importance of respiratory disease at farm, regional or national level. The objective of the present work was to describe the prevalence of gross lung lesions at slaughter, with a special focus on pleuritis and cranio-ventral pulmonary consolidation, and to identify major risk factors for these lesions. Data from 107 farms involving approximately 11,000 pigs enabled gross lung lesions to be correlated with serology to different swine respiratory pathogens as well as with production system characteristics and vaccination schedules. Pleuritis and cranio-ventral pulmonary consolidation lesions were recorded in 26.8% and 55.7% of slaughter-aged pigs, respectively. Among lungs with pleuritis, 50.1% had lesions compatible with Actinobacillus pleuropneumoniae (App) infection. Antibodies to porcine reproductive and respiratory syndrome (PRRSV), three subtypes (H1N1, H1N2 and H3N2) of swine influenza virus (SIV), App and Mycoplasma hyopneumoniae (Mhyo) were highly prevalent (>82%) in most of the farms. In a multivariable analysis, it was estimated (R(2)=0.40) that the percentage of animals with pleuritis compatible with App infection depended on the existence of an all in-all out by room management system and App and PRRSV herd seroprevalence. Moreover, it was possible to foresee (R(2)=0.59) that cranio-ventral pulmonary consolidation lesions (EP-like lesions) were affected by the type of farm ventilation, the presence of respiratory symptoms during the fattening period and Mhyo and SIV H1N2 herd seroprevalence.
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