The Roman deity who protected shepherds and their flocks and was honored on April 21 was Pales.
Pales was an ancient pastoral deity associated with shepherds, flocks, and livestock. Unlike many Roman gods, Pales has no consistently fixed gender: ancient sources sometimes treat Pales as male, sometimes female, and occasionally suggest a plural form. That uncertainty does not change the deity’s distinctive pastoral role.
Pales was honored during the Parilia, a festival held on April 21. The date also marked Rome’s traditional foundation birthday, so a rural rite for shepherds became connected with the civic identity of the city. The festival sought purification and protection for animals, their enclosures, and the people who tended them.
Sheep pens were cleaned and decorated with greenery, while bonfires were prepared with sulfurous smoke. Shepherds offered cakes and milk, and both people and animals could pass through or near the purifying smoke. Pales is sometimes compared with the Greek Pan, but Pan is not the canonical Roman answer here; Flora, Silvanus, and Faunus had related rural associations without matching Pales’s specific festival and pastoral identity.