Sentence:  The creature coming toward me went instantly still. On the other side of the fire, one of them jerked upright and popped its <WSD>ruff</WSD> as wide as it would go. The other lunged to the side of the second and clamped one clawed hand around its muzzle. 
Meaning of the word marked with <WSD> tags:  A collar of lengthened or distinctively coloured fur on or around the neck of an animal.