The Real Reason All Our Wolves Get Open Wounds

The facts are, we see wolves with open wounds in the area around their knees, and only their knees. This happens with such alarming regularity that I personally keep at least two open wound salves in my inventory at all times, and I'm sure larger packs go through them even faster. It happens too often, unless...
Whoever shot all the Skyrim guards with arrows has now made their way to Wolvden and is terrorizing our wolves. The reason we don't ever see the arrows is because they despawn by the time our wolves get back home, leaving only the wound for our herbalists to heal. Thus, our wolves are relegated to the backlines until we can heal them, meaning...
They used to be hunters like you, until they took an arrow to their knee.

This is a pretty humoring theory and I kinda like it. The last line has a ring to it too.

Fun fact: The phrase "took an arrow to the knee" means that the person got married; it's of Scandinavian origin

In my opinion, the blood seems to not trickle down (would be shown with blood stains) suggesting a really big paper cut because if it was an arrow there would be more bleeding. However, one question is why they don't scab up and cause further pain, or why it happens in the same spot every time. I suspect a thorny bush at it would stay at the same place every time and not be deep enough to cause a major injury.

(This theory is based on the opinion that wolvden wolves are like in real life)