Inflamatory Markers in Cows Affected by Subclinical Mastitis Due To Escherichia Coli and Staphylococcus Infections

The investigation of serum amyloid A (SAA), IL-6, and IL-8 concentrations in serum during episodes of clinical and subclinical mastitis is of significant value. The objective of this study was to assess the diagnostic value of Serum Amyloid A (SAA), IL-6, and IL-8 in the early detection of subclinical mastitis in cows infected with Escherichia coli (E. coli) and staphylococcus infections. This cross-sectional analytical study, conducted in 2023 at the Veterinary Laboratory in Urmia, Iran, evaluated inflammatory markers in 79 dairy cows with clinical and subclinical mastitis. The cows were divided into three groups: healthy cows, cows with subclinical mastitis, and cows with clinical mastitis. Each of these groups was then evaluated for Serum Amyloid A (SAA), IL-6, and IL-8. The diagnostic value of the inflammatory markers was determined by calculating the areas under the curves (AUCs) of the receiver operating characteristic (ROC) curves. In general, among patients with a positive culture test result (57%), 19% were found to be infected with E. coli, 22.8% with Streptococcus uberis, and 15.2% (12 cases) with Staphylococcus aureus. A strong correlation was observed between the mean SCC and the values of IL-6 (P<0.005), IL-8 (P<0.005), and SAA (P<0.005). Furthermore, a strong correlation was observed between SAA and IL-8 (P<0.005). The value of IL-6 exhibited a moderate correlation with both IL-8 (P<0.005) and SAA (P<0.005). The sensitivity and specificity of SCC (0.98), SAA (0.90), IL-6 (0.95), and IL-8 (0.87) were high for the diagnosis of mastitis in cows. The present study demonstrated that mastitis in dairy cows is associated with an increase in inflammatory cytokines, including amyloid A, IL-6, and IL-8. The findings of this study indicate that fluctuations in these biomarkers may serve as a potential indicator for disease diagnosis.