Why, oh why are people just so uncaring for their pets? :{
Well done for rescuing and helping them.
If the nipples are hard and crusty, then I am sure that a nice warm bath will help her. Sometimes sows can get stuff embedded on and around their nipples ... I am not entirely sure what it is but it usually responds to being gently removed when bathing.
Having said that, if the nipples are a funny shape and curling around .. sorry I couldn't enlarge your photo ... then an infection should be ruled out first of all.
Hope all goes well xx