The following is an excerpt from the book The Healing Clay by Michel Abehsera:

A person who observes nature can witness the fact that animals instinctively use earth to cure themselves.  Indeed, we owe much of our discovery in this field to animals.  There is a sea resort in the Siberian forests of the Oussouri where the discovery of the curative properties of the earth was the result of observations of wounded animals, wild pigs, roe-deer, red deer and other animals who came to wallow in the benefactory mud.  Dr. Em. Grommier has told the story of the elephant "Fil," who, with his kindred, purged himself with silicic-magnesic clay-marls and daubed himself with mud.

The French Army used it recently for veterinary purposes - when horses were afflicted with hoof gangrene, they were put in a stable, the floor of which had been dug up and kept wet so that the horses could kick in the mud.  The animals went instinctively to the clay-mud where they found a remedy for their disease.

Animals seem to know instinctively the usefulness of contact with clay when they are ill or wounded.  Those living wild to not hesitate to dip the affected area in mud.  Domestic animals, too, turn to clay.  A cat that is abscessed, wounded or ill will lie on a clay case (a large bin of clay covered with a cloth).  Even when not ill, she will prefer this bed to one more comfortable.

Domestic and farm animals can be treated with clay.  The method of treatment is the same as for human patients, the only difficulty being in the docility of the animal in accepting the treatment.  Farm animals can be persuaded to dip themselves into a mud bath prepared by digging a large enough hole filed with clay and water.  Cows have been cured of foot-and-mouth disease (apthous fever) with applications on the feet and daubs in the mouth.  In certain countries, seriously ill animals are saved by daubing them completely with a mixture of clay and vinegar.  Good results are also obtained by replacing vinegar with very salted water (sea salt).

For internal use, clay is also effective.  It can be added to the drinking water (4 soupsoons per quart of unboiled water) and even mixed with food.  It can be used in the fur - particularly for cats, who constantly lick their fur, thus absorbing it easily.