Animal transport takes many shapes. Here's an example of goat mushing in Cambodia, from the flickr-site of those fine folks who make Carryfreedom bicycle trailers. Ouk Chan Bophay of Hosea Ministries writes:
The two guys who are working on making the trailer in the picture are my co-worker. We are working for an organization called Hosea Ministry in Cambodia.
We are working in one village (Veal Thom) that government keeps all kind disability people and the reason that we use goat instead of bike because people in that village hates goat as it eat everything that people grow and also goat is useless, so we try to do something to make people use their goat more than just for sold and eat.
Oh, the guy that riding in the picture is a villager in that village (Veal Thom) he is a disable man (he lost one leg during the war).
Those wheels seem to need some serious truing. But in any case, Carryfreedom not only makes trailers, but also has an open source-initiative for making plans for simple, diy bicycle trailers.