(names of familiar spirits residing in animal hosts)
As is true of so many aspects of Western occultism, the witch's familiar had its origin in shamanism. Every shaman has his own totemic beast, with whom he believed himself to be related by blood. The great spirit of that animal's species, a larger all-white beast that possessed the power of speech, watched over the shaman and protected him from harm, and also taught the shaman occult secrets.
In the Middle Ages, the Inquisitors of the Catholic Church believed the pets of accused witches to be possessed by demons. A witch was supposed to feed her familiar spirit with her own blood, which the animal sucked from her body at a special nipple that became known as a witch's mark. This nipple might be anywhere on the body. It was identifiable to the witch-finders of the Inquisition because it was completely insensitive to pain. A long needle might be thrust into it without the awareness of the witch, if her eyes were covered or averted during the operation.
Remember, in rural Europe five centuries ago sanitation was poor. Any peasant woman might be expected to have numerous unhealed sores, boils, or bites from fleas or other vermin. Add to these blemishes her natural birth marks, moles and skin cancers, and you can see that it would not be difficult for a diligent nun to locate a so-called witch mark on an accused woman's body, if she searched long enough.
The witch did not voluntarily keep a familiar, it was thought, but was compelled to do so by her dark lord, the Devil. The familiar was the Devil's way of insuring the continuing obedience of witches to his evil purposes. The familiar kept tabs on the witch, and constantly urged her on to ever greater acts of mischief. Even so, it was thought that the witch and her familiar were a team, both working for the Devil, bound together by the witch's unholy pact.
The spirit who remained in close association with the witch was the familiar, not the cat or dog or other pet that was thought to be the spirit's physical host. When an old woman suspected of witchcraft was seen by her neighbors talking to her pet cat, the common opinion was that she was conversing with her familiar demon, and plotting evil for her neighbors.
The years of the European witch-crazy were hard for elderly woman, and even harder for cats, particularly black ones. Black cats were associated with Satan because of their color. Cats became the most popular suspect for a witch's familiar because of their uncanny manner of seeming to see things that are not there, and their knowing gaze -- anyone who looks into a cat's eyes can almost believe that some unearthly intelligence resides there. Cats were also natural pets for rural women because they could feed and care for themselves, and kept down the mouse and rat populations in the house and barn.
There is a theory that the great plagues that afflicted Europe during the witch-craze were caused by the systematic extermination of cats. Bubonic plague was spread to humans from the bites of fleas that rode on the backs of rats. Without a stable cat population to control the rats, they spread everywhere and carried the infected fleas with them. I suspect that the growth in the human population of European towns and villages, which overtaxed the already poor sanitation and garbage disposal facilities, was a more significant cause of the plague, but the cat theory is seductive because it seems almost to be a kind of divine retribution for the witch madness that resulted in the deaths of so many innocent women.
Is it really possible for a modern witch or magician to cause a spirit to possess an animal? Yes, but it is usually not convenient to do so. Familiar spirits are very useful. I have one myself who watches over me, teaches me secret matters, and performs other personal services. However, a spirit that is bound into the body of a beast is less versatile since the pet cannot always be with the magician, and on some occasions it may be impossible for the pet to be present. A familiar spirit who is unbound can roam free, and will appear anywhere it is needed at the bidding of its master.
Sometimes it is convenient to localize the familiar upon a particular image or object. This makes the evocation of the familiar easier and more certain. It also insures that the familiar can be controlled, should there ever be a need to imprison it within the object. The best choice is something portable that the magician can carry on his or her body, such as a locket or ring. When a familiar spirit has been made to reside within a ring, for example, it is a very easy matter for the magician to call the spirit out of the ring, or to send it back into the ring. The focus of a physical object which the spirit can use as a kind of matrix enables the spirit to manifest more tangibly and with less effort.
Many who read these words will dismiss the entire subject of familiar spirits are fantasy. I can assure you, familiars are real. The touch of a familiar is as clear and undeniable as the touch of a human being. Only those who have themselves felt a familiar's caress on their cheek, or a familiar's hand upon their shoulder, as I have done, will understand that this statement is completely and literally accurate. There is nothing intangible, ghostly, vague, uncertain, or equivocal about a familiar spirit. They are as real as the shoes on your feet or the hair on your head (which will probably stand on end, the first time you feel a familiar touch you!).