The terrifying bay, heard over a kilometer (0.62 miles) away, even through the howling winds of Pandemonium, heralds the approach of these horrifying beasts. Their paralyzing skill, uncanny intelligence and ruthless ferocity makes them a veritable force on the battlefield that leaves nothing left breathing.
From AD&D to 5th edition these hounds of the lower planes have sewn chaos and destruction anywhere they can be found.
Reading List
Dungeon #88 – Adventure by Robert E. Moore (pg30)
Howler Monkey Cry – National Geographic