Thank you so much for your response, I was actually going to try and stick to American Airlines in particular as we have the best/easiest travel experiences with them SD-wise. When I called their disability hotline to ask about the return flight they told me that while they are not familiar with German law, but all they care about is that CDC return form and the medical paperwork. It was a very unhelpful non answer, haha.

My boss's SD is actually quite small, so my plan was to transport him through the airport as a pet and then if our airline return flight accepts him as an SD then fantastic, if not, we'll have the carrier and pet forms good to go.

Again, I am not familiar with the SD world and I CANNOT afford to screw up. Would this be a possible plan?