Mastitis is a devastating disease condition in the dairy industry throughout the world and is caused due to the inflammation of the mammary gland. The etiological agents causing mastitis varies from one place to another depending on the animal breed, climate, and husbandry practices. However, the etiological agents causing mastitis include an extensive variety of gram-negative and gram-positive bacteria and fungi. Furthermore, the most common bacterial species responsible for causing mastitis include Staphylococcus aureus, Streptococcus dysgalactiae, Streptococcus (Strep.) agalactiae, Strep. Uberis and various Gram-negative bacteria. This review highlights the type of bacteriological etiology causing intramammary infection (IMI) is an essential part of effective mastitis control, prevention, and treatment. It also discusses the diagnostic tests used to test for mastitis in Fiji include Somatic cell count, California Mastitis Test (CMT), and bacteriological culturing. The development of Polymerase Chain Reaction (PCR) technology along with the version of real-time and multiplex PCR has improved the sensitivity and rapidity of mastitis diagnosis. The subclinical and clinical forms of mastitis can be treated with early detection of the signs of mastitis infection. Moreover, it is also essential to create awareness to the farmers about the cost, knowledge about mastitis and the loss it can cause.