Such a shame for the driver and the two wheel horses. (that's what the back two are called?) Road rash hurts like an SOB and usually leaves scars.
Although I had to read the title a time or two before figuring it out. I thought it meant a man was dragging a horse carriage and went out of control, then was thinking, "How out of control can a person-pulled carriage get?"
You jump in the saddle,
Hold onto the bridle!
Jump in the line!
A few weeks ago in old town Sacramento a drunk driving woman hit the horse drawn carriage which is a fixture in this area from behind. Threw the passengers and driver out, no serious injuries and the horse took off. He went to his safe place where he is harnessed and had a few cuts on his legs. The carriage was totaled, amazing no one was killed. They finally found the woman a few days later and she was arrested, many charges against her.