Glad to hear that you are soon to be on your way.
We did the route from Venice to Igoumenitsa in Sept 2005 and our dog came with us.
We were supposed to keep her housed in kennels/cages on the top deck as animals are not allowed in the cabins but we managed to smuggle her down.
We had a great deal of fun sneaking her up and down to the deck for walkies, poos and wees.
Peggy (our dog) is very small and easily fitted under my coat as we dodged the ships crew in hallways, stairs and public areas.
Have a safe journey and keep us informed of your progress.