score:7
A quick google of "Pet friendly cruise" brings up Which Ships Offer Pet Friendly Cruises? which states
When it comes to cruise ships that allow pets, there's only one: Cunard's Queen Mary 2
But then goes on to state
.. you can bring your dog or cat, but that doesn't mean your fuzzy family members will be able to snuggle with you in your cabin. They'll be confined to their own digs in an onboard kennel on Deck 12, where dedicated crew members feed, walk and clean up after them in addition to lavishing them with treats and toys
Every other link seems to show day cruises only and I don't think that is what you are looking for.
I also found Is There Such a Thing as a Pet-Friendly Cruise?, and the key quote from this is
The main reasons other cruise lines donβt allow animals on board: hygieneβships have strict sanitation codesβand port regulations. Each country has its own entry requirements for animals, so navigating multiple-country cruises would be a headache for ships and pet owners alike.
Finally, Want To Bring Your Pet On A Cruise? Pet Friendly Cruises talks from the perspective of service animals on ships (and is basically the same advice as the previous links). But as you are talking about pets, the advice there is moot.