Commentary Inf XXXIII 28-36

Ugolino's dream turns out to have been completely accurate: Ruggieri, out hunting on Mount San Giuliano, is after Ugolino (the wolf) and his children (the cubs). He has set, ahead of the chase, the waiting ambushers, the Ghibelline leaders of Pisa, and with his hounds he is driving his victims toward them and to their destruction.

For the canine imagery in Cocytus and especially in this canto, see Brugnoli (Brug.1989.1).