C-reactive protein quantification in porcine saliva: A minimally invasive test for pig health monitoring

Study objectives were to investigate whether C-reactive protein (CRP) in pig saliva could be quantified using an adapted, time-resolved immunofluorometry assay (TR-IFMA), and to determine whether the assay could distinguish healthy from diseased animals. The test method had intra- and inter-assay coefficients of variation of 5.75% and 9.73%, respectively, the limit of detection was 0.47 ng/mL and the coefficient of determination was 0.98. Analysis of CRP concentrations in paired serum and saliva samples from 50 pigs gave a positive correlation (r = 0.702, P < 0.01) and the salivary CRP concentration was able to distinguish healthy from diseased animals in 62 samples from pigs with naturally occurring or experimentally-induced inflammation. The results suggest that this minimally invasive, straightforward and sensitive assay may be useful in pig health and welfare monitoring.