>>398451451. Zoonotic infections are a real thing and it will probably end up killing the animal since they haven't evolved under the immunological pressure having mucous membrane contact with a species that routinely spread pathogens worldwide for the past several millennia
2. Domestic animals do not have the cognitive capacity to even be capable of having informed consent for sexual contact with another species
3. Unintended physical harm can occur due to incompatible reproductive anatomy