I believe that this was in the same light, the “milk sacks” being a part of the reproductive or animalistic aspect of creatures. Most cultures used slaves or women from the underclasses to act as milk maids, people who weren’t seen as being intellectually equal.
As with all historical studies, there is some debate regarding how significant the genital issue was to them and exactly what it implied. And there isn’t a lot of intensive research in that specific field. But, I digress.
Thanks for the toe tip, tip!