The other day walking across the bridge I saw one such boy coasting down the hill to the bridge at a good clip. One of his donkeys—on the right in the picture—either stumbled or came out of the harness and was run over by the cart. The axle passed over its hips, pinning it to the ground. I went over to help, and found the cart much heavier than I was expecting. Many carts are made of the removed bed of a bakkie (pickup truck), usually stripped down and half rusted through, and are therefore relatively light. You can see in the picture this one is made out of welded plate steel. It was incredibly heavy. I'm pretty strong (for a PCV anyway), and it was nearly all I (with the help of some Grade 4s) could do to lift the thing and shift it enough to allow the donkey to squirm out.
Luckily the donkey's legs didn't seem to be broken, and so the boy just strapped it back in and, with a few blows of the whip, they were back on their way.