Vet school didn't pan out for me; I ended up leaving halfway through second year. At this stage in my life, I'm kind of stuck not knowing what to do. My BS in biology isn't enough for me to snag a job paying anywhere near enough to service the $100k+ in debt that I have, so I languish away, barely paying anything, on PAYE. I don't even really make enough where I am now to move somewhere where I could find those jobs, so I'm pretty trapped. Due to that debt and the fact that I've now been out of academia entirely for over three years, I'm extremely hesitant to pursue more schooling at this time. Ultimately, I don't think vet med was the career for me to begin with---I have certain psychiatric concerns and personality traits that just don't mesh well with the demands of the profession, particularly in the realm of GP/ER (likely where I would have ended up with my grades being what they were)---and it sucks that I only learnt that after I already had sunk so much time and money into the vet school thing. But I honestly should have left before I was too deep into the hole; I began having reservations as early on as the first semester.
Anyway, if I could do it all over again, knowing what I know now... I probably would have still gotten my BS in biology, but would have very strongly considered doing a minor or possibly even a second major in computer science, then pursue graduate school in biostatistics, computational biology, or bioinformatics instead. I've been coding as a hobby since before high school, so I honestly don't know why that career route never crossed my mind in the first place. It can be about as lucrative as vet med with an MS or PhD with considerably less financial investment.
I have so many regrets that I kick myself for. Every. Day. I'm glad that you're considering backup careers in case things don't turn out the way you're hoping for vet school; many pre-vets don't, unfortunately. Sometimes life throws us curve balls, so it's always apt to be prepared for such things.