Someone posted a question about animal ghosts–saying they could not find anything out there about them. There are numerous pages up about ghost animals such as this one from New Zealand but the Gutenberg Project has one you can download by Elliott O’Donnell.
There are also numerous books in print about animal ghosts or pet ghosts…here are a few you might want to check out. The debate is always ongoing because science looks for proof that such entities exist and ultimately you have to investigate and make the decisions on your own but Spiritualists and the Rosacrucians both talk about such entities.
There are many other similar titles but I know these to be some of the better ones out there.