The Queen Mary 2 is the only ship where you can take your dog with you on a crossing or cruise.
They have kennels and a full time kennel master.
The wearecunard.com blog has written about it, as has a lady who runs a blog about dogs and her own pet called Pepper. the blog is called "Pepper in Paris"
On that she has a posting about the trip and what you need to do.
She also has a video of the trip with pictures which she describs as " A dog on the Queen Mary 2! Pepper, a Miniature Schnauzer from New York City travels to Paris, via South Hampton and Hamburg, on Cunard's ocean liner, the Queen Mary 2. Follow all of this adventures... click here to watch on YouTube or on the blog posting.
To read her blog post: