As pointed out in the previous article on Mastitis, treatment of mastitis should be accompanied by the initiation of various sanitary measures. Treatment without improvement of the sanitation in milking of the herd is almost certain to be unsatisfactory in the long run, because of subsequent reinfection of treated animals. The treatment should be considered as an adjunct to a control program rather than depending on it to control the disease alone. The average practitioner of veterinary medicine is called on more frequently to treat an acute case of mastitis in a herd where little or no sanitation in milking is practiced and too often the owner is unwilling to take the steps necessary to control the disease. However, there is an increase in the number of dairy herd owners who, through costly experience, are now willing to take all measures to control mastitis.