This is one of those things that used to happen all the time and has really fallen by the wayside. For all that vets tout the flexibility of the job and finding a different career within vet med, it’s becoming a lot more uncommon for that to come to fruition.
I went into vet school wanting to pursue lab animal. I didn’t match and spent five and half years in SA GP before getting a job in lab animal without needing a residency.
I considered applying to residency programs after a couple years out, but like others have said, programs are becoming increasingly unfavorable to that approach. They want fresh grads with recent connections/education that they can shape. They don’t want practitioners with “bad habits” (quote from large LAM program).
The other factors are lifestyle-related but still very important: giving up your clinician salary for resident money, especially if starting a family or paying off student loans. Location was also a big one for me as we’d already bought a nice house in a good neighborhood with good schools and it would have been really hard to stomach a move to a really bad area with awful traffic.
It worked out well for me, but I’d definitely recommend doing at least an intern year if you aren’t sure; it buys you one more year to consider your options without effectively closing the door.