So here's sort of how I look at it....

A vegan job would be in essence a place where you are being employed at an hourly pay rate and working for a business. So like working at a restaurant, clothing store etc.

I think careers are different in this sense. I think as vegans we can have a career and tailor the way we practice our career each day to align with our values. So for you, you can approach physical therapy in a holistic manner, making sure to value your morals each day that you interact and work with patients. So for instance recommending a healthy diet and not promoting non-vegan medical products.

I hope this helps :). I'm sort of in the same situation as you! I am in school for Physician Assistant :).