**Abstract**

Bovine mastitis is one of the most important bacterial diseases of dairy cattle throughout the world. Mastitis is responsible for great economic losses to the dairy producer and to the milk processing industry resulting from reduced milk production, alterations in milk composition, discarded milk, increased replacement costs, extra labor, treatment costs, and veterinary services. Economic losses due to bovine mastitis are estimated to be \$2 billion in the United States, \$400 million in Canada (Canadian Bovine Mastitis and Milk Quality Research Network-CBMQRN) and \$130 million in Australia per year. Many factors can influence the development of mastitis; however, inflammation of the mammary gland is usually a consequence of adhesion, invasion, and colonization of the mammary gland by one or more mastitis pathogens such as *Staphylococcus aureus*, *Streptococcus uberis*, and *Escherichia coli*.

**Keywords:** mastitis, bovine, *Staphylococcus*, *Streptococcus*
