Survey of pulmonary lesions and pleuritis in slaughter-aged pigs in Italy

Cranio-ventral pulmonary consolidation (EP-like lesions) and chronic pleuritis (CP) are common findings in slaughtered pigs. Pleural lesions involving dorso-caudal lobes are suggestive of pleuropneumonia due to Actinobacillus pleuropneumoniae (App). The aims of the present study were to investigate the prevalence of lung and pleural lesions at abattoirs in Italy and to identify major factors potentially associated with the prevalence and the severity of the lesions.

The lungs of 4896 pigs, 9 to 10 months old, belonging to 50 Italian herds (25 vaccinated and 25 unvaccinated for App) were scored at the slaughterhouse for lung and pleural lesions according to Madec’s grid and to the Slaughterhouse Pleuritis Evaluation System (SPES) respectively. For each batch the EP-like average value, the SPES average value, i.e. the sum of each lung score/number of scored lungs, and the APP index, i.e. the frequency of pleuritis lesions with a SPES score ≥2 in a batch*mean pleuritis lesion score of animals with SPES ≥2 were calculated. Twenty blood samples were collected at 10, 18 weeks of age and at slaughter from each batch and tested for M. hyo (ELISA IDvet), App-ApxIV, PRRS (ELISA IDEXX) and SIV (HI test for H1N1, H3N2, H1N2). Each farm was visited by a swine veterinarian and data about farm characteristics, herd size, pig flow, type of floor and ventilation, description of RD on the farm, history of pleuropneumoniae in the previous 2 years and vaccination programs were collected using a questionnaire. The association between the questionnaire results, seroprevalence and lung lesions were analyzed using non-parametric tests.

EP-like lesions were detected in 2188 (44.7%) lungs and the average value was 0.95 (st. dev. 0.38). Chronic pleuritis were recorded in 2614 (53.4%) lungs. Dorso-caudal pleuritis, suggestive of recovered pleuropneumonia, was found in 1214 lungs (24.8%). The mean SPES value of all lungs was 0.8 (st. dev. 0.35). The mean APPI of all studied batches was 0.6 (st. dev. 0.35). The mean SPES and APPI values per batches were statistically associated with App seroprevalence (P< 0.05, Pearson r 0.28 and 0.37 respectively) and higher in farms with history of App (P< 0.05) isolation.

Chronic pleuritis and cranio-ventral pulmonary consolidation are frequently observed in pigs at abattoirs in Italy, suggesting a detrimental economic effect on pig production. The results of this study highlight that a history of App isolation and its seroprevalence are risk factors for dorsocaudal chronic pleuritis.

Disclosure of Interest: None Declared.