I agree that the argument from non-consensuality does not hold water, but there is a different argument - interspecies sex carries the risk of contracting a dis

I agree that the argument from non-consensuality does not hold water, but there is a different argument - interspecies sex carries the risk of contracting a disease. This carries the act from the land of consenting adults (plus a non-consenting-but-who-cares animal) to endangering the whole population - germs that cross the inter-species barrier tend to be nasty ones.