It's just an entry level job. Working with animals. Casual setting. I know I shouldn't dress as casual as the people who already work there, but I'd feel out of place dressed to the nines. What should I wear?
Also by the way it's cold where I am right now, though the interview is going to be inside.
If you have to choose between being underdressed or overdressed you want to be overdressed. Wearing appropriate business type clothing shows that you respect the employer and that you're serious about wanting the job. No one is going to hold it against you if you're "overdressed" compared to the way people who work there are dressed on a day to day basis.