I’ve heard a few accounts of people encountering ghosts of pets and other domesticated animals, as well as wild animals or animals that may never have been animals to start with, including some tales of family guardians/totems.
Sometimes these stories get debunked as with the woman who thought her cat had returned, because sand being dragged in from a nearby lot where her cat had liked to go, but found it was only falling of her granddaughter’s stuffed toy.
For myself, I’ve had a possible experience with ghost animals. This happened sometime between 1999 and 2003. I was staying the night at a friend’s house, and they had two dogs; a corgi with a cropped tail, and a lab. The corgi slept with my friend and the lab slept with the parents.
During the night, curled up in my sleeping bag, I felt a dog step over me and it’s tail smacking me. I figured it was the lab (since the corgi had very little tail) and just went back to sleep whenever it happened. I looked around once, but didn’t see anything, so I assumed the dog had gone back downstairs. In the morning I told my friend the lab had been coming up and bugging me. The parents however kept the door closed (as they later confirmed), therefore lab couldn’t have left their room.
However, my friend then explained to me that the room we’d been sleeping in had once been used to breed dogs. The former owner apparently was not very good about this, and several of the dogs had died in that room. So obviously, my friend figured, it may have been the spirit of one of these dogs that I’d encountered.