Evaluation of oxidative stress in plasma of dairy cows with mastitis

Abstract

Bovine mastitis is associated with an endogenous antibacterial response mediated by the production of reactive species. However, excess oxidative reactions can trigger cellular apoptosis, aggravating the clinical state of the animals. In this context, the objective of this study was to evaluate the plasma redox response of dairy cows with and without mastitis submitted or not to antibiotic therapy. The cows were divided into control group (G1), cows without mastitis; group G2, cows with mastitis without antimicrobial treatment; group G3, cows with mastitis treated with antibiotics. Blood samples were collected after the first milking of the morning. The existence of lipoperoxidation (LPO) and the levels of carbonylated proteins (CPs), reduced glutathione (GSH), ascorbic acid (ASA), and uric acid (UA) were analyzed. The G3 animals showed increase in LPO and CPs. In all groups GSH levels were unchanged. Plasma ASA and AU values were decreased in the G2 and G3 groups. The results demonstrated that antimicrobial treatment seems to aggravate the oxidative damages present in bovine mastitis, reinforcing the importance of the search for therapeutic alternatives in order to minimize this effect.