Legally you have the right to refuse to partake in dissections. In reality? Good luck. I submitted to the faculty dean with the support of the faculty of science a request to do my biology credits sans dissections both on moral and health risk grounds as I had an allergy to the preservative used in specimens. They just ignored all letters and attempts to contact them forcing me to pick between dealing with the problems of pursing the career or changing majors. I ended up picking to do the latter. That said, I know some schools use cadavers donated for science in place of animal dissections. You would have to ask around at different surgical schools though. I discovered the big university here uses animals, but the smaller one uses cadavers for some reason. No idea why they can get them and the bigger ones couldn’t but yeah, look around and ask. I’m assuming you are ok here with humans who donated their body to be used for dissection and it’s just animals killed for that sole purpose which is the issue?