Line 70, Canto 32 "doglike"

In Dante Alighieri's "Inferno" in Canto XXXII on Line 70, it says:
"And after that I saw a thousand faces
made doglike by the cold; for which I shudder-
and always will- when I face frozen fords."

Now this is during his travels across "The Ninth Circle of Hell, the First Ring, in which Traitors to their Kin are immersed in the ice, heads bent down."

First question. When he says "heads bent down" does that mean they are stuck in the ice with their head at the greatest depth compared to their body? (so legs stick out of the ice while the heads are submerged like the people of The Eighth Circle, Third Pouch, where the Simonists are set, heads down, into holes in the rock, with their protruding feet tormented by flames.)

Second question. When it says that their faces became doglike what qualities of a dogs face do you suppose he refers to?