Pet Ghost is a resource.
See also: Petsmount Ghost.
Pet Ghosts are the ghosts of pets which have died. The pet either died due to negligence on the owner's part (see Keeping Your Pet Alive) or was put down on purpose by a Hunter in order to provide food for a Pink Dragoone, or to access the Pet Sanctuary.
A pet killed by a Hunter loses all the statistic bonuses it had gained from feeding. This makes them stackable in one's inventory, so that several butchered Bow Meows, for example, occupy only one item slot. The ghosts of pets which die due to the owner's negligence keep their stats.
Pet Ghosts can be brought to life again in several ways.
Firstly by obtaining a Resurrection Powder (either buying it from the Resource market, or completing the Pet Sanctuary dungeon) then exchanging the pet ghost and the powder with Sorim Ait outside Amakna Castle at [3,-5] for an alive pet with the same stats but 1 HP. Butchered pets will not recover lost stat points.