Robbers didn't take your bulls? Strange I say, because when I was travelling with 3x dogs, 2x bovines and 2x pigs (in v3.52), they did take ALL lashed animals (the dogs were unleashed before fight, and I've found them later).
I'm also curious about who dragged you, but from my experience it's rare if there are only three robbers. Usually there are 5 or 6. Sometimes it looks as if there are two, I kill them with arrows, but usually they are just a vanguard it seems, the others being far away enough to be disinterested.
The dogs may be not dead, because they ran away temporarily, or were unconscious and left to die. But it may be they are treated as a non-threat by AI, once you are down.
Though I think it may be the algorithm doesn't take all circumstances into consideration, and always drops the character away, even if it is the sole survivor. By the way, the things dropped may be protected partially from taking. Also although they took all my animals in my case, they left some masterwork items I had in inventory (like a handaxe) and other stuff.
Additionally there may be some roleplaying as an explanation - that it is the character, wounded and delirious, who just wandered away before regaining his senses. The text doesn't say that the character is dropped, it says "You come to your senses in unfamiliar surroundings".