Definitely use sources, but they don’t necessarily have to be research papers as your sources. co 22’s cycle was about working dogs and vet care and I used articles from the AVMA, AAVMC, National Geographic, NPR, ABC News (about a specific military working dog), and only one actual journal that had a case study. Mine was about 6500 characters with spaces, excluding the bibliography, but that’s only because I was really excited about and into the topic. Im not sure exactly what the essay topic is this year, but if you can, find some part about the topic that really interests you and just go at it. Write about what interests YOU about the topic, not just what you think the admissions committee wants to hear. Remember, they have to read hundreds of these same essays.