Evaluation of homocysteine and neutrophil-to-lymphocyte ratio as biomarkers in bovine respiratory disease

Bovine respiratory disease (BRD) is a prevalent infection characterized by severe systemic inflammation and oxidative stress. This study aimed to evaluate serum homocysteine levels and neutrophil-to-lymphocyte ratios (NLR) as potential biomarkers of systemic inflammation in cattle with BRD, alongside routine hematological parameters, and to investigate the diagnostic relationships among them. Blood samples obtained from 30 diseased and 20 healthy cattle, diagnosed with BRD via clinical examination and scoring indices, were analyzed for homocysteine, NLR, and hematological data. According to the findings, homocysteine levels in the study group were statistically significantly lower compared to the control group, whereas the NLR was significantly higher. While distinct decreases in RBC and HCT values were detected in the diseased group, no significant difference was observed in WBC and Hb levels. In correlation analyses, although physically interrelated classical hematological parameters demonstrated strong positive correlations, no relationship was found between these parameters and NLR or homocysteine. In this study examining the dynamics of inflammation in BRD, it was postulated that the observed decrease in homocysteine may stem from aggressive metabolic consumption during the synthesis of cellular antioxidants and acute-phase proteins, which increase secondary to inflammation. In light of the current clinical findings, it can be suggested that NLR is a cost-effective and highly practical auxiliary diagnostic tool for the diagnosis and prognostic monitoring of BRD in the veterinary field.