An inflammation of the mammary gland may result in clinical mastitis with varying degrees of visible signs of the disease or subclinical mastitis where no visible symptoms occur. Pathogenic bacteria entering the udder via the teat orifice move into the teat canal and cause an infectious response. Contagious bacteria (Streptococcus agalactiae and Staphylococcus aureus) are more difficult to control than environmental pathogens such as coliform. The goal of a sound mastitis control program is to minimize bacteria that enter the udder plus minimize the growth of bacteria in the udder