Rabies ------ Ferrets are assumed to be highly susceptible to rabies and capable of transmitting the virus. Vaccination trials using standard rabies vaccines have never been carried out to determine the protective value of such vaccines. Consequently, it is not known if the vaccines currently being given are protective, and if so, for how long. In spite of these facts, a killed rabies vaccine should be given annually, starting at 3 months of age. Of course, there is a danger that such a vaccine may produce a false sense of security. Nevertheless, it is unlikely that an average domestic ferret, living in an urban household, will come into contact with rabies virus by way of a bite or contact with the saliva of a rabid animal.