In a females normal heat cycle, thier nipples will enlarge, but they carry no milk. Only a female who has been bred or has experienced a false pregnancy without being bred will have milk in thier nipples. If your female has milk in her nipples, but ther was no breeding done, she would have to be going through a false pregnancy. Can you squeeze anything from the nipples in question? If a milky,bloody,puss like substance comes out, she has an infection and will need to be on antibiotics. If nothing comes out when you squeeze them and they are hard lumps, I would say she has mammary tumors and a biopsy needs to be done.