"Alle țe filț of his magh ['maw'] salle breste out atte his fondament for drede." ["Cursor Mundi," c.1340]
... to put ginger up a horse's fundament, and formerly, as it is said, a live eel, to make him lively and carry his tail well; it is said, a forfeit is incurred by any horse-dealer's servant, who shall shew a horse without first feaguing him. Feague is used, figuratively, for encouraging or spiriting one up.