I've seen a bit like that in a picture in a book with artifacts from ancient Egypt.
HOW do you get that bit back in their mouth the 2nd time?!?!?
As for the first two pictures, I really don't see a large bit to be worried about, without any backround story. Atleast the donkey looks to be in good health. There are plenty of animals who are skin and bones who can't even begin to look healthy who have loads much worse that this guy does. He also appears to have a padded harness, rather than the rope that you often see, digging into the animal's skin.