In the Dominican Office, as in the Roman, of course no use is made of Alleluia from after first Vespers of Septuagesima until Easter Sunday. In place of that heavenly word, after the initial Glory be of each Hour, we sing the earthly words Laus tibi, Domine, Rex æternæ gloriæ.
From this day until Easter (excepting 3rd class feasts until Ash Wednesday - and from that day on never save on the few feasts of 1st and 2nd class: the Chair of St Peter; St Matthias; for Dominicans, St Thomas Aquinas; for Australians and the Irish, St Patrick; St Joseph; the Annunciation), no Te Deum is said at Matins, nor Gloria in excelsis sung at Mass. (To avoid such festal joy entirely during the penitential season before Easter, the Mozarabic and Ambrosian Rites moved all such feasts out of Lent.)
At Lauds of ferias from now till Easter, the second, more penitential set of psalms are used, beginning every day with Psalm 50, the Miserere. On Sunday, moreover, Psalm 117 is sung next at Lauds (not as usual at Prime, where Psalm 53 substitutes), thus entirely omitting the joyful Psalms 92 and 99.
The old, longer daily canticles of Lauds, those used before the reforms of Pope St Pius X, also reappear: on Monday, Confitebor tibi, the Canticle of Isaias; on Tuesday, Ego dixi, the Canticle of Ezechias (Hezekiah); on Wednesday, Exsultavit cor meum, the Canticle of Anna; on Thursday, Cantemus Domino, the triumphant Canticle of Moses at the Red Sea; on Friday, Domine audivi, the Canticle of Habacuc; on Saturday, Audite cæli, the terrible Canticle of Moses against faithless Israel. On Sunday, however, lest the Hour be too burdensome by reason of length, in place of the traditional Benedicite is sung the shorter Benedictus es, also from the Canticle of the Three Young Men.
Furthermore, in the Dominican Rite, on all ferias (as has been the case since the end of Christmastide on the 13th) the preces - threefold Kyrie and Pater noster - are said at Lauds, at Terce, Sext, and None, and at Vespers, before the Dominus vobiscum and collect.
Once Lent begins, the ferial days thereof take precedence of all 3rd class feasts, which are reduced to a Memorial at Lauds.
Already, from Septuagesima Sunday, the way the short responsories at Terce, Sext and None are read changes: the respond (the initial line) is not repeated at once as usual, but instead the versicle is said directly, then the second half of the respond (after the asterisk) as usual, then the Glory be, then the respond in full, thus:
(This variation is proper to the Dominican Rite.)