Yep my ducks will go after small snakes and the chickens too, but some of our Blk snakes are 6'long and very big around and go after the ducks eggs. I don't think they will tangle with big blackie. I'm glad your dog survived being bitten TLWR that had to have been scary.
We have some pretty large Blk rat snakes around these parts 6' and they come into the duck/chickens house quite often I've gotten pretty brave about getting them out, I done gloves and use a rake to hold the snake down till I can pick it up behind the head then I carry it down the road a ways...