Here's a prayer to silence a dog:
Field maiden, farmyard girl! O golden king of earth,
here where they need thee, come from the field with thy
family to close the mouth of a dog, to plug the nozzle of a
whelp. Bind silk across its eyes, tie a bandage round its
ears, a mushroom up one nostril thrust, an apple up the
other one, lest it should scent the breath of man, perceive
the smell of a full-grown man, lest it should hear a passer-
by, lest it should see a wanderer.
Try it and let me know if it works! There's two more in the book, if this one doesn't do the trick.
Abercromby, John Abercromby, baron, 1844-1924. The Pre- And Proto-historic Finns, Both Eastern And Western, With the Magic Songs of the West Finns. London: D. Nutt, 1898. p. 216.