Animal ghost

An animal ghost is, presumably, the ghost of a dead magical animal. Mopsy Fleabert wrote a book on British animal ghosts: Animal Ghosts of Britain.

Behind the Scenes

 * The term animal ghost is only given on Pottermore. No examples are given which animals actually can become animal ghosts.
 * It is likely that ghost horses are examples of animal ghosts.
 * Gytrashes are described as dog spirits. It is possible that they are a form of animal ghosts.

Appearances
Pottermore (mentioned only)