what is the correct way for it to be sold? do you need a shtar, (assuming the animal cannot be picked up). or is kinyan kessef enough? like if the non Jew pays you $2.00 cash are you fully covered?
Heard on a yutorah shiur (I think R Sobolofsky?) that we do the same combination of mechanisms as with selling chametz. Cash, handshake, real estate, you name it. (I heard a story of a fellow in Baltimore who owned some ewes and kept them on some farmland that didn't belong to him. As he had to sell part of them to a non-Jew via land he owned, he brought them onto his yard, a couple blocks away from the Agudah shul, and Rabbi Heinemann shlit'a presided over the sale.)