Irish ferries, dog question?

We've a couple of trips to France organised.....
We only book one way as the return date is unknown....
So far we always use Stena, but looking at other users.....
Now looking at the return trips and wondering if anyone can answer the following re: Irish Ferries, and in particular the Oscar Wilde?

1. Is it possible to leave our dog in the MH on the crossing rather than the kennel option
2. If yes to question 1, then what is the visiting arrangements on board.

Jon

Thanks for that Mark.
Sort of rules out Irish ferries for us.
We will use stena as usual.

Thanks @lookaround..... We have used Stena before, our dog needs to be on board the MH for the crossing as she gets stressed in kennels.
So Irish Ferries are ruled out on that ground.