The French archaeologist Patrice Méniel has demonstrated, based on examination of animal bones from many archaeological sites, a lack of hippophagy (horse eating) in ritual centres and burial sites in Gaul, although there is some evidence for hippophagy from earlier settlement sites in the same region (Méniel 1992 pp.38-45, 77-78, 131-143).
Tacitus (Germania) mentions the use of white horses for divination by the Germanic tribes:
Horse oracles are also attested in later times (see Arkona reference below).
There is some reason to believe that Poseidon, like other water gods, was originally conceived under the form of a horse. In Greek art, Poseidon rides a chariot that was pulled by a hippocampus or by horses that could ride on the sea, and sailors sometimes drowned horses as a sacrifice to Poseidon to ensure a safe voyage.
In the cave of Phigalia Demeter was, according to popular tradition, represented with the head and mane of a horse, possibly a relic of the time when a non-specialized corn-spirit bore this form. Her priests were called Poloi (Greek for "colts") in Laconia.
This seems relater to the archaic myth by which Poseidon once pursued Demeter; She spurned his advances, turning herself into a mare so that she could hide in a herd of horses; he saw through the deception and became a stallion and captured her. Their child was a horse, Arion, which was capable of human speech.
The Welsh legend of Rhiannon and the Irish legend of Macha, although first recorded in Christian times, may indicate memories of horse worship. The white horse of Rhiannon is another example of cultic use of white horses, which seems to be an Indo-European phenomenon (Hyland p.6).
The temple fortress of Arkona, at Cape Arkona on the German island of Rügen, was the religious centre of the Slavic Rani in the Early Middle Ages. The temple, dedicated to the deity Svantevit, housed an important horse oracle in Slavic times, where the behaviour of a white stallion could decide peace or war - recalling the above account by Tacitus.