Environmental is pretty huge. Includes CO2 emissions and antibiotic-resistance superbugs (and superbugs caused by C02 emissions for that matter). You could call that ethics but it is broader than animal welfare.
Health is mentioned a lot, although that seems to be a reason people who are not vegan think they might go vegan. I think my health has improved along with going vegan but my diet is not pristine at all and I did not magically become thin.