Another "previous page" mishnah! In a place where they had the practice to sell "small" domesticated animals - sheep and goats - to non-Jews, they were permitted to do so. And in places where they didn't have the practice - they were not allowed to. But large livestock was not permitted in either place. Though some allowed the sale in the event of some damage to the large animals. Plus, the concern of these work-animals working on Shabbat. Also, a Jew cannot keep their own large animals in the stable of a non-Jew's inn, because of concerns of bestiality - an uncomfortable concern to be sure. Also, the question of selling a cow via a broker vs. selling directly (which seems like it should be prohibited). To what extent must the Jew be conscientious about selling things to non-Jews who might use those same things in ways that are objectionable in Judaism (eg - animals that would work the land during a sabbatical year). With many permutations that seem to depend on the seller's clear assumptions about the buyer.