Turning a man into an animal can to difficult. to make things easier give him aspects of the animal. Give him big donkey ears, a hairy face and a tale. This will give the audience the idea of him being turned into a donkey but not loosing him human qualities. This is also simpler for makeup because most of his face is still free and not much needs to be applied to the face. He can still use facial expressions.
Works Cited: Google search- midsummer night's dream characters