Immune and inflammatory biomarkers in cases of bovine perinatal mortality with and without infection in utero

The objective of this study was to compare acute-phase protein [serum amyloid A (SAA) and haptoglobin (Hp)] and immunoglobulin G1 and M concentrations in blood plasma of cases of bovine perinatal mortality due to infection in utero or traumotocia and in unexplained cases. Plasma samples were collected from 110 stillborn calves with bacterial infection (INF_B, n = 16), with viral or parasitic infection (INF_V/P, n = 31) during pregnancy, with lesions of fatal traumotocia (TRAUM, n = 22), and from unexplained deaths (UNEXPL, n = 41). Plasma immunoglobulin and SAA concentrations were measured by ELISA, and Hp concentrations were measured by the guaiacol method and ELISA. Concentrations of SAA in the INF_B group were higher than in the UNEXPL group and tended to be higher than in the INF_V/P group. A reference range (0-29 mg/L) was established for SAA in stillborn calves. Concentrations of Hp tended to be higher in the INF_B group compared with INF_V/P group. Concentrations of IgM tended to be higher in the INF_B group compared with the TRAUM and INF_V/P groups. Concentrations of IgG1 were numerically, but not significantly, higher in the INF_V/P and INF_B groups compared with the other groups. The results demonstrate upregulation of immune and inflammatory responses in stillborn calves exposed to bacterial infection in utero. The immune-inflammatory parameters did not differ between calves with viral or parasitic infections and traumotocia. These immune-inflammatory profiles did not contribute to the diagnosis of unexplained stillbirth. This is the first report of an elevated acute phase protein response in stillborn calves. Measurement of SAA and IgM concentrations may be used in the diagnosis of bacterial infections in stillborn calves.