Risk factors associated with pleuritis and cranio-ventral pulmonary consolidation in slaughter-aged pigs

A study carried out by researchers of the CReSA and IRTA reports pleuritis and cranio-ventral pulmonary consolidation lesions in 26.8% and 55.7% of slaughter-aged pigs in Spain, respectively. Among lungs with pleuritis, 50.1% had lesions compatible with Actinobacillus pleuropneumoniae (App) infection.

Pleuritis and cranio-ventral pulmonary consolidation are the most frequent findings in pig lungs at slaughter and are associated with significant economic losses, primarily due to reduction in growth performance and feed efficiency. Moreover, the facilitation of concomitant infections in these animals and the increased treatment are additional economic losses that must be taken into account. Several environmental factors and infectious agents have been associated with the occurrence of lung lesions in swine, and Mycoplasma hyopneumoniae (Mhyo) and App are considered to be the most important primary bacterial respiratory pathogens.

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 in Spain, 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.

Results obtained in this study can be summarized:

  • Pleuritis and cranio-ventral pulmonary consolidation lesions were recorded in 26.8% and 55.7% of slaughter-aged pigs in Spain, respectively.
  • Among lungs with pleuritis, 50.1% had lesions compatible with App infection. Antibodies to Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), three subtypes (H1N1, H1N2 and H3N2) of Swine Influenza Virus (SIV), App and Mhyo were highly prevalent (>82%) in most of the farms.
  • In a multivariable analysis, it was estimated that the percentage of animals with pleuritis compatible with App infection depended on the existence of all in-all out by room management and App and PRRSV herd seroprevalence.
  • It was possible to foresee that cranio-ventral pulmonary consolidation lesions (Enzootic pneumonia-like lesions) were affected by the type of farm ventilation, the presence of respiratory symptoms during the fattening period and Mhyo and SIV H1N2herd seroprevalence.

This study will be published as “Risk factors associated with pleuritis and cranio-ventral pulmonary consolidation in slaughter-aged pigs (L. Fraile, A. Alegre, R. López-Jiménez, M. Nofrarías, J. Segalés)” in The Veterinary Journal. It concludes that pleuritis and cranio-ventral pulmonary consolidation are frequent lung lesions in pigs at slaughter in Spain, suggesting substantial economic losses. Measures focused on the control of App and Mhyo, as well as other pathogens such as PRRSV and SIV H1N2, combined with management improvements at farm level (all in-all out strategies and ventilation), should have a significant impact in reducing both pleurisy and EP-like lesions occurrence.

To contact with the author of this study:

Lorenzo Fraile Sauce
Researcher
Epidemiology Unit (CReSA)
Email: lorenzo.fraile@cresa.uab.cat
Telephone no.: +34 935814495
Fax: +34 935814490
Edifici CReSA. Campus UAB
08193 Bellaterra (Barcelona) España


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