The dog as keeper of the home, guardian of the threshold sacred to the women, is common in antiquity. As women's companions, black dogs were thought to be demon lovers in disguise because women petted and caressed them. A black dog was believed to be the witch's helper in gathering the ingredients for charms. In the context of Christian legend, to be called a son of a bitch is insulting not because one is a dog but because one is a devil, the spiritual son of the pagan Goddess. Our culture doesn't remember all the parts of this story and ignores others, yet the superstition that dogs can see the spirits of the dead persists around the world to this day.
History is written by the winners.
It is a lot easier to spread a story if you are powerful. How we communicate is always interrelated with power. Women's stories especially suffered as Christians took control of the West. The inherent wickedness of women was written into the Bible from its opening tale of the fall of man. In the sixth century, churchmen even denied women had souls.