The Dairy industry knows mastitis inside and out (there are mastitis "home pages", newsletters) because when a cow's milk supply falls off someone loses money (estimates are $200 annually per cow in the USA). One of the major causes of mastitis in dairy animals is injury to the breast (udder) tissue. Of course, cows step on each other's teats, or catch them on fences, and lie around in messy stuff. One can study the information of trauma and mastitis in dairy animals and see that much can be extrapolated to human mammary tissue. I suggest it as a handy way to obtain broad info -- especially if you have Internet surfing ability. Any time you have milk that can remain static in the breast -- due to physical injury or anamoly -- you set up opportunity for a mastitis. If only human milk production had a dollar value as noticable as that of Bessy the cow, we'd all know more. Margery Wilson, IBCLC Cambridge, MA USA