Receiver operating characteristic curve analysis to determine the diagnostic performance of serum haptoglobin concentration for the diagnosis of acute puerperal metritis in dairy cows

Acute puerperal metritis (APM) in dairy cows is characterized by fever and fetid vaginal discharge within 21 days in milk (DIM). Increased serum haptoglobin concentration (Hp) can support the diagnosis of APM. However, there is a dearth of information of the test performance of Hp as a measure for APM with a consistent definition and considering parity. The objective of this trial was to study the test performance of Hp to distinguish healthy cows from cows with APM. A total of 33 of 60 (55.0%) primiparous cows and 43 of 133 (32.3%) multiparous cows developed APM. Primiparous cows with APM had the greatest Hp. However, in primiparous cows Hp did not significantly differ between healthy cows (DIM 2: 1.49 ± 0.64 mg/mL; DIM 5: 2.13 ± 0.66 mg/mL; DIM 10: 1.46 ± 0.85 mg/mL) and cows with APM (DIM 2: 1.78 ± 0.62 mg/mL; DIM 5: 2.48 ± 0.64 mg/mL; DIM 10: 1.60 ± 0.81 mg/mL). In multiparous cows, Hp was greater in cows with APM (DIM 2: 1.27 ± 0.68 mg/mL; DIM 5: 1.89 ± 0.94 mg/mL; DIM 10: 1.23 ± 0.78 mg/mL) than in healthy cows (DIM 2: 0.99 ± 0.68 mg/mL; DIM 5: 1.10 ± 0.80 mg/mL; DIM 10: 0.83 ± 0.68 mg/mL). Sensitivity and specificity of Hp to diagnose APM in multiparous cows ranged from 72% to 79% and 54% to 71% on DIM 2, 5 and 10, respectively.