Veterinarians can check their accreditation status at: https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/nvap/ct_areavet
Click Check My Accreditation Status. This will provide you with your Category, Renewal Date and all State(s) where you are Authorized.
The GVL system will check the veterinarian's accreditation before signing certificates that require it.