Abstract: Background and Objective: Mastitis causes significant economic losses in dairy industry globally. The present study evaluated levels of Blood Urea Nitrogen (BUN) and lipid peroxidation (LPO) along with enzymic activities of lactate dehydrogenase (LDH), alkaline phosphatase (ALP)and glutathione peroxidase (GPx) in the serum samples, lipid peroxidation (LPO) and activities of glutathione peroxidase (GPx) in skimmedmilk of dairy animals (cows and buffaloes) showing sub-clinical mastitis (SCM) and clinical mastitis. Methodology: A total of 100 lactating animals were divided into two groups i.e., cattle and buffaloes, each group contain 50 animals. Each group is further divided into three subgroups healthy (10), sub-clinical mastitis (20) and clinical mastitis (20). Blood serum and defatted milk were used for enzyme activity estimations. Results: The LDH and ALP activities along with LPO levels were significantly higher (p<0.05) in SCM and CM the milk as compared to healthy milk from udders. Non significant differences were observed in BUN values. The mean activities of GPx were significantly reduced (p<0.05) in SCM and CM milk than in healthy milk. Increased lipid peroxidation in serum and milk indicated direct correlation between oxidative stress and tissue damage in clinical and sub-clinical mastitis in dairy animals. Conclusion: From the present study, it may be suggested that optimum antioxidant intake carry sufficient potential in affording protection against sub-clinical and clinical mastitis in the dairy animals.