"Hound" refers to one of the various canines found in Crawl. While they are among the weaker kinds of monsters you can find, they are all faster than the average character and tend to run in packs. They can mostly be found in the Dungeon and the Lair (especially in the hound-themed Lair ending), though a couple varieties can be found in more unusual locations. Many of them can be summoned with the spell Call Canine Familiar.
h Jackal - Low-level pack-hunters that inhabit the early Dungeon. Individually weak, but a pack can bring down a low-level adventurer if they catch him out in the open.
h Hound - Swift and solitary dogs found in the earlier portions of the Dungeon. Quite delicious.
h War dog - War-trained dogs with painful bites and a pack mentality. Found both in the Lair and in the company of Grum.
h Wolf - Wild creatures found in Ice Caves and near spriggan encampments. Has multiple attacks.
h Warg - Huge, bestial wolves who live in the Orcish Mines with their orcish masters. Resistant to poison.
h Hell hound - Demonic, fire-breathing dogs found mostly in and around the Hells. Occasionally appears elsewhere.