Why not just a simple braid, or get a little fancier and use doubled strands, giving you six strands? Unless you have a real monster or one that like to chew, that should be more than enough.
I was at the docks where our local commecial fishermen berth and make repairs and watched a fellow tie up his golden retreiver with some 3/4″ line. He was barely down in the hold before the dog had chewed through the rope and wandered down the dock. I was amazed how easily the mutt bit through the line.