Simple SummaryThe aim of the present study was to investigate a measurable biomarker for the detection and differentiation of mastitis in cows. We chose procalcitonin as a candidate because it is synthesized during inflammation of bacterial origin. We tested the marker in milk and serum in healthy cows and those with subclinical and clinical mastitis. The results show that procalcitonin is suitable for the detection and differentiation of mastitis in cows and thus can be a potential biomarker.AbstractMastitis is one of the most common diseases of dairy cows. Procalcitonin (PCT) has been described as an endogenous inflammatory biomarker for bacterial infections. The aim of this study was to find possible correlations between PCT concentrations in the serum and milk of cows with mastitis and their clinical signs and disease progression. In total, 88 dairy cows were examined, of which 30 animals were diagnosed with clinical mastitis, 30 had subclinical mastitis, and 28 were designated as a healthy control group. The diseased animals were re-examined after 12 days. All PCT levels in this study were determined by a species-specific ELISA. All three groups could be differentiated from each other based on serum and milk PCT levels. The animals with clinical mastitis showed the highest mean concentrations of PCT (serum: 2641 pg/mL; milk: 1326 pg/mL), and the lowest PCT concentrations were found in the healthy control group (serum: 1166 pg/mL; milk: 176 pg/m). Over the course of the disease, results from the kinetics study showed that PCT levels remained high for the entire observation period. The results from this study showed that the PCT concentration could be used to differentiate between clinical mastitis, subclinical mastitis, and healthy cows.