The dogs came on, holding together, each dog keeping the tail of the preceding dog in his mouth, as the priests do when they are going to sing praises with the Vahishpavamâna hymn. After they had settled down, they began to say Hin.

In plain words: The dogs arrived in a line, each holding the tail of the dog in front in its mouth. This is how priests walk when they go to sing a sacred hymn. Then they sat down and began chanting the sound "Hin."