The case for cats and dogs.
Other animals such as common cats and dogs may have been living with with humans for thousands of years. The animals would have served the same practical purposes they do today. Early wood-block illustrations provide evidence that buccaneers indeed kept hunting dogs. There is also evidence that domestic animals were taken on voyages. Some scientists believe that the extinction of the Dodo Bird is directly related to the introduction of pigs, cats, and dogs to the Mauritius Island, the birds only habitat. We can assume that what was good enough for merchant ships was also good enough for a pirate ship. A good mouser on sailing ship is worth it weight in mice eaten.
Pirates were also a superstitious lot. During this time (and still today in some circles) the British merchant seaman considered the possession of black cats good luck. It was a common practice for the loved ones of a merchant marine to keep a black cat in the house while he was at sea. It was believed that so long as the cat was well fed and kept safe from harm, nothing would happen to the mariner.
Sailors also kept cats on board ships to bring them luck. Other superstitions involving sailors and cats claimed if the ship's cat approached a sailor, it meant good luck. If the cat approached halfway and turned away, bad luck would surely follow. If a cat was thrown overboard, a storm would rise and very bad luck would follow
Polydactyl cats (cats with extra toes) were always a good thing on board ships. Sailors were long-known to especially value polydactyl cats for their extraordinary climbing and hunting abilities as an aid in controlling shipboard rodents. Some sailors also considered them to be extremely good luck when at sea. Today, such cats are found throughout England and the Eastern Seaboard of the United States!.
There is no reason to doubt that an English pirate or his lover would not hold the same belief as that of other merchants of the sea.