The nurse will appreciate the reason for all of this painstaking care if she calls to mind the fact that the breast tissues are highly vascular and excessively active at this time and therefore very susceptible to infection, and also that the baby’s suckling is often very vigorous and accompanied by a good deal of chewing and gnawing of the nipples. Unless the nipples have been toughened, and sometimes even when they have, the skin becomes abraded or cracked as a result of the baby’s suckling, thus creating a portal of entry for infecting organisms, in addition to the milk ducts which lead back into the breast tissues. Unless the nipples are kept clean, constantly, they may become infected by organisms from the baby’s mouth or on the patient’s hands, bedding or gown with a breast abscess as a result. The important thing, then, is to keep the nipples clean and not allow anything unsterile, excepting the baby’s mouth, to come in contact with them at any time. [Illustration: FIG. 120.—Protecting cracked nipples by having the baby nurse through a shield. (From photograph taken at Johns Hopkins Hospital.) ] It is sometimes the practice to swab the baby’s mouth with boric soaked cotton or gauze before each nursing, but many doctors hold that this is injurious to the delicate mucous lining of the baby’s mouth. The opinions for and against this routine seem to be about equally prevalent. [Illustration: FIG. 121.—Nipple shield used in Fig. 120. ] If the nipples become painful or cracked, one can easily understand that continued suckling would only aggravate the condition and increase the danger of infection. But the baby must nurse, if possible, and so in the majority of cases a nipple shield is used (Figs. 120–121) as a protection, and after nursing the fissures or abraded areas are painted with bismuth and castor oil paste; compound tincture of benzoin; balsam of Peru; argyrol, silver nitrate or sometimes only alcohol. The application is made with sterile swabs prepared by twisting a wisp of cotton about the end of a toothpick. If the crack or abrasion is extensive enough to cause bleeding, even nursing through a shield is sometimes, but not necessarily discontinued, while the other treatment is the same as for a nipple that does not bleed. Sound, uninjured nipples, then, are to be kept clean and protected from infection and those which are abraded or cracked are to be kept clean and also protected against further injury.