So it depends on whether you want to do emergency as a non specialist, or be a boarded criticalist.
If wanting to be a criticalist, after vet school you will need to do a 1 year rotating internship followed by a 3 year residency and then your speciality board exams. Research during school will help you with this, as well as spending time shadowing/volunteering in ERs to get experience with the ECC environment and caseload.
If wanting to be an ER doctor without being boarded, there aren’t really many requirements. You can either do a 1 year rotating internship before going into it, or you can go straight from graduation to an ER with strong mentorship. Many people recommend a rotating internship or at the very least one of the corporate mentorship programs, and I’m inclined to agree with that. I heavily considered this option, although I eventually decided to go the ECC specialist route (above). With the current staffing situation, having the type of mentorship you need to set yourself up for success as a new grad is becoming trickier. Of the two friends of mine who went straight into ER practice, I think both of them were very overwhelmed at the beginning (even though both had significant ER experience while students). If you choose this option you NEED to spend a significant amount of time in ERs before graduation. I can’t imagine walking into ER as a new grad without having a solid ER base. The practice environment, caseload, and really everything is very different than GP and it is not for everyone. I’m not as strongly against new grads going into ER without an internship as a lot of people are, but I definitely understand their view and the reasons behind it.
My background for this is that I am a critical care resident who previously spent significant time in ER private practice (and was debating taking that job out of school directly). Ultimately I did an internship because I hadn’t ruled out specializing, and decided fairly early on in my internship that residency was the way I was going to go. Feel free to message me if you want to chat further or have additional questions.