The disclosed invention is directed to (1) recombinant bovine herpesvirus genes having foreign genes inserted therein, (2) infectious recombinant bovine herpesviruses carrying these recombinant genes, (3) methods of producing these recombinant bovine herpesviruses, (4) methods of immunizing animals against diseases caused by bovine herpesviruses using these recombinant bovine herpesviruses as vaccines, and (5) methods of detecting infection of an animal by these recombinant bovine herpesviruses. In its preferred form, the invention is directed to the construction of an infectious recombinant bovine herpesvirus type 1 having a functional &bgr;-galactosidase gene inserted in and thereby inactivating the thymidine kinase gene (e.g., Gal-TK); infection of an animal with the resultant avirulent vaccine virus is detected by assaying the animal's respiratory secretions for the presence of virus having &bgr;-galactosidase activity in host cells.