In the United States, stray dog control programs initiated in the 1940s, combined with routine rabies vaccination of owned dogs, eliminated the canine rabies virus variant (strain) from circulation by 2008. The elimination of this variant of an almost uniformly fatal virus from a domestic animal species that lives as a companion in close contact with humans has saved both canine and human lives. Today, in the United States and Canada, dogs (and humans) remain at risk from host-adapted rabies virus variants in wildlife reservoir species such as skunks, raccoons, foxes, and bats. The extent of spillover from wildlife is driven by the wildlife reservoir in the endemic area, with spillover most common in areas with the raccoon variant, somewhat less with skunk variants, and least common in areas where only bat variants occur. The US CDC publish an annual rabies surveillance summary that includes useful maps illustrating the distribution of terrestrial rabies virus variants as well as spillover events into dogs. Links to recent publications on rabies and rabies epidemiology are available at https://www.cdc.gov/rabies/resources/publications/index.html. The Canadian Food Inspection Agency (CFIA) also compiles rabies statistics at https://inspection.canada.ca/animalhealth/terrestrial-animals/diseases/reportable/rabies/rabies-incanada/eng/1356156989919/1356157139999.
Because of the high fatality rate and public health risk posed by rabies infection, administration of rabies vaccine to dogs is legally mandated in many jurisdictions. Age at initial vaccination, timing of booster doses, vaccine formulation, response to overdue booster doses, and whether rabies vaccine exemptions are permitted may all be stipulated in laws or regulations. Mandates can exist at the local, state, and provincial levels, and veterinarians should be aware of all applicable requirements in their area. Veterinarians that serve clients in multiple jurisdictions with variable requirements should generally apply the requirements of the jurisdiction where the animal resides. Local and state health departments (https://www.cdc.gov/rabies/resources/contacts.html) and state public health veterinarians (listed at http://nasphv.org/Documents/StatePublicHealthVeterinariansByState.pdf) are important sources of information about vaccine requirements, local rabies epidemiology, animal rabies testing, and risk assessments following a possible rabies exposure.
Rabies vaccines are highly immunogenic and effective. Vaccine failures are rarely reported. In jurisdictions where it is not mandated, rabies is recommended as a core vaccine, used in accordance with the most current recommendations in the Compendium of Animal Rabies Prevention and Control (http://www.nasphv.org/documentsCompendia.html). Currently, all licensed rabies vaccines for dogs are inactivated (killed) with 1 and 3 yr DOI formulations available. All licensed products are labeled for puppies 3 mo of age and older. A booster dose is recommended 1 yr following the initial vaccination regardless of the formulation or age at initial vaccination. The booster’s purpose is to immunize any animals that failed to respond to the initial dose. At this time, there are no published data supporting the efficacy of half-doses of rabies vaccine.
Legal exemptions from rabies vaccination requirements are only available in certain jurisdictions. Because exposure to rabies poses a risk to both animal and human health in unvaccinated or undervaccinated dogs, possible exemptions should be discussed with the owner in the context of the animal’s health and lifestyle (i.e., risk of exposure). Veterinarians should document these discussions in the medical record. Antibody titer levels as correlates of protection have not been established for rabies, and serologic testing is not considered a substitute for vaccination.20–25