Showrunners Joe Wiseman and Joe Port said that season 4 would feature an animal ghost for the first time, adding that the “Very small” animal would become a “Sort of ghost pet.” Adding animal ghosts seems to mean the mansion should be much busier, since the spirits of every animal that ever died on its grounds should number in the millions. Although Ghosts is hardly a paragon of realism, it is hard to see how the show will simply ignore this oversight. Ghosts changed some of the original British show’s formula, but the show still sticks with some rules.
For example, any ghost who completes their purpose on earth can be “Sucked off,” to use the parlance of the sheltered ghosts, into the afterlife. This might be used to excuse the lack of animal ghosts on the show’s property, as the same rules could apply to animals. If this is the case, it would make sense for Ghosts season 4 to reveal that the vast majority of animals pass into the afterlife without pause, which explains why it is so rare for the characters to encounter an animal ghost. However, the series may not offer even this much explanation.
