This is what they did recently in the diocese of Lyons. When preaching there against sorcery and hearing confessions, I heard many women confess that they had carried their children to St. Guinefort. I thought he was some saint. I made inquiries and at last heard that he was a certain greyhound killed in the following way. In the diocese of Lyons, close to the vill of the nuns called Villeneuve, on the land belonging to the lord of Villars-en-Dombe, there was a certain castle whose lord had a baby son from his wife. But when the lord and lady and the nurse too had left the house, leaving the child alone in his cradle, a very large snake entered the house and made for the child’s cradle. The greyhound, who had remained there, saw this, dashed swiftly under the cradle in pursuit, knocking it over, and attacked the snake with its fangs and answering bite with bite. In the end the dog killed it and threw it far away from the child’s cradle which he left all bloodied as was his mouth and head, with the snake’s blood, and stood there by the cradle all beaten about by the snake. When the nurse came back and saw this, she thought the child had been killed and eaten by the dog and so gave out an almighty scream. The child’s mother heard this, rushed in, saw and thought the same and she too screamed. Then the knight similarly once he got there believed the same, and drawing his sword killed the dog. Only then did they approach the child and find him unharmed, sleeping sweetly in fact. On further investigation, they discovered the snake torn up by the dog’s bites and dead. Now that they had learned the truth of the matter, they were embarrassed that they had so unjustly killed a dog so useful to them and threw his body into a well in front of the castle gate, and placing over it a very large heap of stones they planted trees nearby as a memorial of the deed.
But the castle was in due course destroyed by divine will, and the land reduced to a desert abandoned by its inhabitants. The local peasants hearing of the dog’s noble deed and innocent death, began to visit the place and honor the dog as a martyr in quest of help for their sicknesses and other needs. They were seduced and often cheated by the Devil so that he might in this way lead men into error. Women especially, with sick or poorly children, carried them to the place, and went off a league to another nearby castle where an old woman could teach them a ritual for making offerings and invocations to the demons and lead them to the right spot. When they got there, they offered salt and certain other things, hung the child’s little clothes on the bramble bushes around, fixing them on the thorns. They then put the naked baby through the opening between the trunks of two trees, the mother standing on one side and throwing her child nine times to the old woman on the other side, while invoking the demons to adjure the fauns in the wood of “Rimite” to take the sick and failing child which they said belonged to them (the fauns) and return to them their own child big, plump, live and healthy. Once this was done, the killer mothers took the baby and placed it naked at the foot of the tree on the straws of a cradle, lit at both ends two candles a thumbsbreadth thick with fire they had brought with them and fastened them on the trunk above. Then, while the candles were consumed, they went far enough away that they could neither hear nor see the child. In this way the burning candles burned up and killed a number of babies, as we have heard from others in the same place.
One woman told me that after she had invoked the fauns and left, she saw a wolf leaving the wood and going to the child and the wolf (or the devil in wolf’s form, so she said) would have devoured it had she not been moved by her maternal feelings and prevented it. On the other hand, if when they returned they found the child alive, they picked it up and carried it to a swiftly flowing river nearby, called the Chalaronne [tributary of the Saône], and immersed it nine times, to the point where if it escaped dying on the spot or soon after, it must have had very tough innards.
We went to the place and assembled the people and preached against the practice. We then had the dead dog dug up and the grove of trees cut down and burned along with the dog’s bones. Then we had an edict enacted by the lords of the land threatening the spoliation and fining of any people who gathered there for such a purpose in future. — De Supersticione, Stephen de Bourbon
It’s probably worth noting that the legend of St. Guinefort, like so many saints, grew out of older folklore. There is a pretty solid disentangling of the story at Lapham’s Quarterly. Basically, the ‘faithful hound’ story (which has Welsh, Indian, and other versions) was apparently incorporated into the story of an actual saint, and garbled together. The healing ritual described by de Bourbon is itself probably a sensationalized version of an older pagan ritual, as de Bourbon was a sort of inquisitor, rooting out heresy. So there is probably a “real” saint somewhere … filtered through folklore, superstition, and an inquisitor’s penchant for finding the Devil behind things.
As far as I can tell there were not a lot of animals revered as saints. In fact the only other case I can think of is St. Christopher, who was often depicted as dog-headed (but ultimately still human).
The hagiographies of many human saints involve many animal-related miracles, such as animals raised from the dead or healed, animal companions, and extraordinary encounters with helpful wild animals. For example several Irish saints resurrect animals like geese during their lives, and a number of English saints, working posthumously through their shrines, raised cattle and horses from the dead. Other saints speak with animals, are given warnings by birds, or are offered protection by wild animals.