Greatmaw hounds were four-legged aggressive creatures who inhabited Barasin Refuse Yards on the planet Balmorra

Balmorra Planet

during and after Cold War. Greatmaws had two huge bony tusks that protruded from their jaws, each of their front paws had two huge claws. Despite their aggressivness they were strictly territorial creatures and weren't attacking until someone venture directly in their territory.
The Greatmaw Hounds were somehow related to the Sith Hounds

Sith Hound Creature Non-sentient

, some scientists thought they were actually the same creatures. The most noticeable visual difference between the two species was the size of their tusks - the tusks of the Greatmaws were several times larger.
While Sith Hounds were almost exclusively found among their Sith masters, Greatmaws were more common in their natural environment.
During the Dread War

Dread War Event Galactic War (3642BBY - 3636BBY)

on the moon Oricon

Oricon Planet

Greatmaws - called Dread Hounds or Dread Beasts - were trained and used as guard beasts by the members of the Dread Guard

Dread Guard Organization Dread Empire

.