I don't think they will call all of your references. As far as I know, none of my four have been interviewed. I'm really close with one of my major advisors, who has written LORs for other vet students in the past, and I see her a couple times a week. She hasn't been called for me or any students in the past. Another one of my references lives in South Africa, so I doubt she will get called. My other two references are veterinarians, one of which used to be the head vet at UGA's small animal clinic, but she moved to Denver. She hasn't told me if she has been called, but I never asked. The other vet is actually on UGA's admissions committee, so she won't (can't?) tell me anything and I'm way too scared to even ask her anything about the admissions process, haha.
Bottom line, don't panic if your references haven't been called. They probably aren't even supposed to tell you if they were called! Good luck everyone! 🙂