Can't find blood trail

[SulphuricChipmunk]

Ok, so what happened with me is that I got attacked by a wolf right outside my shelter (the gas station, by the back entrance). I got up, went inside, slept for at least 8 hours, went back outside the next morning and while I could clearly see my own blood trail from the attack, I couldn't see the wolf's. Is it intentional that wolves might not leave a blood trail after a fight, is it a bug, or something else.

[selfless]

Animal blood trails fade depending on weather, but none remain for 8 hours.  Your blood is more permanent. 

I don't know why...