The «suggested» revaccination «recommendation» on Boehringer Ingelheim's Protech
C3 label reads: «Annual vaccination Either Protech C3 + Protech C2i and Protech Bronchi - Shield III Or Protech C4 + Protech C2i and Protech Bronchi - Shield I. Protech C3 and Protech C4 have been assessed as providing at least 12 months protection against canine distemper virus, canine adenovirus and canine parvovirus.