you may be surprised because i am mature man and i cant tell you what it really is. two of my dogs nipples look bigger and they a pink compared to the rest and i squeezed them a bit just to feel if they were swollen and milky stuff came out. my dog can jump out and we are in the middle of raising our fences so it could be possible. but is milky distarge normal or could she be pregnant? i dont know what to do. maybe i have to go to the vet and he will tell be definitely what is with my dog. because i dont know what to do in such situations on my own.