Milk is one of the most important foods of human being and is recognised globally as a complete diet due to presence of essential components required for human health. India is a premier milk producing country of the world and fabulously rich in dairy cows. Diseases of dairy cows achieve greatest importance and amongst which mastitis possesses highest clinical and economical significance. Mastitis is an inflammation of the parenchyma of the mammary gland regardless of the cause and is characterized by a range of physical and chemical changes in the milk and pathologic changes in the glandular tissue [3]. Clinically mastitis is classified into two categories-clinical mastitis and sub-clinical mastitis. Sub-clinical mastitis is characterized by the no visual changes in the quarter (s) and milk, or the existence of inflammation without presence of gross signs [14]. Subclinical mastitis (SCM) in cows is more prevalent in India (varying from 10-50%) than clinical mastitis (1-10%). Average loss of milk yield due to subclinical mastitis is up to 17.5%[12]. Subclinical form of mastitis in dairy cows is more important due to 15-40 times more prevalent than the clinical form, its long duration, difficult to detect, perpetual economic loss for longer duration, adverse effect on milk quality which usually goes unnoticed and of not properly attended, leads to clinical form of mastitis [13]. Inadequate sanitation, hygiene and veterinary services were found to be predisposing factors associated with prevalence and spread of subclinical mastitis in cows [15]. Diagnosis of subclinical mastitis is much more difficult as there are neither visual abnormalities in the milk nor inflammatory changes in the mammary gland.