My uncle told me of a use of "dogging" over a hundred years ago. Down in Belfast,ME, the city let a contract for care of the poor in a separate residence provided by a farmer.
One of the residents on the "poor farm" had a daughter who got pregnant without benefit of clergy. When the girl's father tried to arrange a "shotgun wedding" but did not own a shotgun, he was told:"Keep your bitches to home when they are dogging."