Dogs and cats are quite sensitive to ghosts

No shit Sherlock.. my dog and cat were constantly freaking us out.

Animals staring pointedly at a specific area in the room and trying to peer around you if you moved into their line of sight. Dog would bark happily, tail wagging and jumping up at thin air as though a known human was there playing with him. Cat sitting on back of chair, growling and hackles raised for no reason.

I hated being alone in the house when they did this. Gave me the willies.