There is a long tradition of animal mascots aboard ships. For centuries many Royal Navy and merchant vessels carried cats or dogs, which not only provided companionship for the crew but also traditionally served as rat-catchers.
In A kiwi on our funnel by Gerry Wright, there is an account of mascot dogs on two Royal New Zealand Navy minesweepers serving during the Indonesian Confrontation in 1965.
All the Inshore Flotilla ships carried a mascot dog. [HMNZS] Hickleton's dog was named Hickleberry Hound, 'Hick' for short, and was a keen visitor to the naval base wet canteen with his minder ME1 Edwards and the crew. [HMNZS] Stanton's dog, recruited by Ordinary Seaman Fisher, was a bitch named 'Sandy'. The role of these two unofficial shipmates was to provide moral support at sea; a task at which they excelled.... Unfortunately for Sandy, after about a year of service, she was on heat at the time of one of the few graunch transfers between the Hickleton and Santon at sea. The opportunity was not missed by either animal and soon after Sandy began showing signs of the transfer. Sadly, both dogs were later lost overboard at sea during the night under suspicious circumstances. Sandy was not replaced but Hick jr. was to later appear in Borneo.