The commissioner may refuse to grant permits to import animals from any and all sections or areas which in his opinion are infected with a contagious disease, and he may, at any time, revoke any permit previously issued and then outstanding, for the importation into this state of animals which in his opinion are infected, and all damages caused or claimed to have been caused by such revocation shall be borne by the owner. All neat cattle and goats entering the state shall be identified by ear tags, registration name or number, tattoo or other markings approved by the commissioner.