I found it thought provoking too! I don't recall anywhere in scripture where animals were demon possessed. Those poor pigs, to rather die than have a demon! Who says they aren't SMART??? LOL
I think the scriptures are clear that unsaved people do have demons. (the man who "cleaned" his house and was possessed by demons worse than those he cast out) Demons manifest themselves in the personalities of the unsaved. They are not all violent. I believe that ghosts are nothing more than demons who have not found a new host. It would make sense too for those who claim that they have lived other lives.... they just have a demon who has indwelt people through the ages and affects their consciousness.
Any other thoughts on that? I am moving this weekend so all of my things are packed up!
LOL God Bless!