Serum acute phase proteins as biomarkers of pleuritis and cranio-ventral pulmonary consolidation in slaughter-aged pigs.

The purpose of this study was to investigate the relationship between the existence of lung lesions in pigs at slaughter and the concentration of the serum acute phase proteins (APP), haptoglobin (Hp), pig-major acute protein (Pig-MAP) and C-reactive protein (CRP). A total of 24 pig farms were selected out of a larger farm database previously screened to study risk factors associated with pleuritis and cranio-ventral pulmonary consolidation (CVPC) lesions at slaughter-aged pigs in Spain. The farms were classified as "pleuritis negative (P-) or positive (P+)" and as "CVPC negative (M-) or positive (M+)" and divided into four groups according to a 2X2 factorial design (P-M-, P-M+, P+M-, P+M+). Also at slaughter, blood from 20 randomly selected pigs from each farm was collected. Obtained serum samples were used to measure acute phase proteins. All APP concentrations were significantly higher for M+ farms than for M- ones. However, only Hp and Pig-MAP showed significantly higher concentrations for P+ farms than for P- ones. Pig-MAP was the most sensitive biomarker since it was able to clearly discriminate between P-/P+ and M-/M+ groups (p<0.001 in both cases). Hp was an excellent marker for pleuritis and good for CVPC lesions. CRP was able to discriminate for CVPC lesions but not for pleuritis. The present results indicate that Pig-MAP and, possibly Hp, may be used as potential markers to characterise and discriminate respiratory lesions in swine herds at slaughter.