We like to cruise too and our dog did very well, but he was glad to see us when we got back. The staff spoiled him rotten (if that were possible) and I was told they argued about who would take him potty.
I missed him terribly and the only way to find out how he was doing was by email that took forever because phone service is not always available at ports and non existant on most ships not to mention the expense. She should be fine and having a buddy with her will make it even better. So take a deep breath and enjoy yourself. She is at the vet so if any emergency comes up she is covered. She may even enjoy her stay meeting all the new doggies.
Enjoy your cruise and tell us about it when you return.