In the 1909 Breviarium S.O.P., the feast had the rank of "simplex", which would be considered a commemoration according to the rubrics of the 1962 Office. At Vespers and Lauds, an antiphon, versicle/response and collect pray are given in the Proper of the Saints. They are the same as those from the saints feast day on May 5.
The collect prayer, which is taken from his feast day, recalls the role he played in the historic defense of Christendom from Muslim invaders in the 16th Century. Given the plight of so many Christians today, this time in the Middle East, but elsewhere as well, who are suffering such gruesome persecution, I will be making these commemorations and asking St. Pius' intercession on their behalf.
Commemoration at I Vespers:
Magnif. ant.: Pious deeds vindicate his name of Pius; henceforth all generations will call him blessed, alleluia.
℣. Blessed Pius pray for us, alleluia. ℟. That we may be made worthy of the promises of Christ, alleluia.
Collect
O God, for the defeat of the church's foes and the restoration of divine worship, you were pleased to choose the blessed Pius to be Sovereign Pontiff; grant that we may be shielded by his watchfulness, and so abide in your holy service that, overcoming the wiles of all our enemies, we may enjoy unending peace. Through our Lord...Commemoration at Lauds:
Bened. ant.: Pius, wonderful shepherd, be mindful of your sheep; plead before the supreme Judge for the lands of the faithful, alleluia.
℣. The just man shall blossom as the lily, alleluia. ℟. And he will flourish before the Lord for ever, alleluia.
Collect: O God, for the defeat...Commemoration at II Vespers:
Magnif. ant.: He who exalts the humble exalted Pius, and placed him on the apostolic throne, alleluia.
℣. Blessed Pius pray for us, alleluia. ℟. That we may be made worthy of the promises of Christ, alleluia.
Collect: O God, for the defeat...St. Pius V, pray for all Christians being persecuted throughout the world.