pastor (n.)

c. 1300, "land covered with vegetation suitable for grazing;" also "grass eaten by cattle or other animals," from Old French pasture "fodder, grass eaten by cattle" (12c., Modern French pâture), from Late Latin pastura "a feeding, grazing," from Latin pastus, past participle of pascere "to feed, graze," from PIE root *pa- "to feed." To be out to pasture in the figurative sense of "retired" is by 1945, from where horses were sent (ideally) after their active working life.

late 13c., pastron, "shackle fixed on the foot of a horse or other beast," from Old French pasturon (Modern French paturon), diminutive of pasture "shackle for a horse in pasture," from Vulgar Latin *pastoria, noun use of fem. of Latin pastorius "of herdsmen," from pastor "shepherd" (see pastor). Metathesis of -r- and the following vowel occurred 1500s. The original sense is obsolete; the meaning was extended by 1520s to the part of the horse's leg between the fetlock and the hoof, to which the tether was attached.