“The poison of a serpent, the venom of the dog, the sharpness of the spear, doth not well in man. The blood of one dog, the blood of many dogs, the blood of the hound of Fliethas–these I invoke. It is not a wart to which my spittle is applied. I strike disease; I strike wounds. I strike the disease of the dog that bites, of the thorn that wounds, of the iron that strikes. I invoke the three daughters of Fliethas against the serpent.
Benediction on this body to be healed; benediction on the spittle; benediction on him who casts out the disease. In the name of God Amen” –Source
Fliethas is a ruler within the Tuatha, and to some a Fairy Queen. She is a shepard of the fairy cattle, watcher of sacred wells, and a tender to the land and those that dwell on it.
At times, she is invoked, such as the prayer above, when she is needed to heal the ailments caused from fairy mischief and malevolence. You can state the prayer quoted above over a bottle of milk, and she will bless it with her fairy healing. The milk should be drank by the one ailed by various fairy wounds from their darts, blasts, and strikes. White animals, especially cattle and deer, are said to belong to her flock, and all these animals are most sacred to her. It is also worth noting that she also owns a fairy hound (A fairy hound is slightly different from a Cu Sith, which are noted as green or covered in vegetation)