When using an adjuvanted vaccine (an adjuvant is an agent added to a vaccine to help stimulate the immune system) approved for 3 years, there is no difference as far as local laws are concerned. What makes your pet's rabies vaccination good for one year or three years is determined by two things:
- The animal's age and rabies vaccine history
- If the state and municipal laws require annual vaccinations for rabies.
Dogs and cats are first vaccinated for rabies between 4 and 6 months of age. They need a booster one year from that date. They are then vaccinated every three years, although some states still require annual rabies vaccinations for dogs and/or cats. Again, it is the same vaccine in all cases, but the time it is good for is dependent on these factors.
General Confusion About Vaccinations
There have been lots of discussions (and confusion) about cat and dog vaccinations. How often, what vaccinations are really necessary, do risks outweigh benefits, and so on. The standard of care for decades was to vaccinate dogs and cats annually for several common diseases, without much "choice" about specific vaccinations or schedules. The recommendation from the American Animal Hospital Association (AAHA) and most veterinarians and is to vaccinate every three years, with careful selection of the vaccines needed for each specific pet.
Rabies the Disease vs. Rabies the Vaccine
The one exception to vaccine "choice" is the rabies vaccine. It is the only vaccination required by law in the United States, as rabies is a fatal disease. It is also a zoonotic disease, meaning it may be transmitted from animals to humans. There is no cure for rabies. Vaccinating for rabies will help an animal mount an immune system response to protect against rabies, but it isn't a curative treatment.
How Long Do Vaccines Offer Protection?
This is the big question. There isn't one answer. How long a vaccine, rabies or otherwise, is "good" for, in terms of actual disease protection is still debated. The vaccine, the health of the individual and their immune system, the disease agents, all of these factors come into play.
Titers have been touted as a way to measure protection, but this is still a topic under discussion. A titer is a blood test that measures antibody levels; the immune system's reminder of previous exposure to an infectious agent or vaccine. This is not necessarily a measure of how the body will react to a new challenge with the disease agent. Titers aren't harmful to run and do provide some information. There is a cost involved to run these test(s). Speak with your veterinarian for their opinion and to discuss if this is a useful protocol for your pet.
Adjuvanted vs. Non-Adjuvanted Vaccines
Thanks to a 1991 letter to the editor in the Journal of the American Veterinary Medical Association, a possible connection to adjuvanted rabies vaccines and sarcomas in cats was raised. This discussion led to the formation of the Vaccine-Associated Feline Sarcoma Task Force to tabulate and track vaccination data.
As a result of these studies, non-adjuvanted vaccines are now available; the only non-adjuvanted rabies vaccine for cats at this writing (2011) is Purevax, manufactured by Merial. It is labeled for 1 year — cats who receive this vaccination must be revaccinated annually (every year), according to labeling.
From the VAFSTF: "While a specific cause has not been established, it is thought that inflammatory processes related to administration of injectable products can lead to the formation of sarcomas. The role of adjuvants (including those containing aluminum) and local inflammation in the pathogenesis of FISS is not clear. (An adjuvant is a substance added to the vaccine to increase the effectiveness of the component antigens, such as killed microorganisms in an induction of an immune response.)"
From UC Davis College of Veterinary Medicine: "We currently stock and suggest the use of the recombinant rabies vaccine, because there is some evidence that it is associated with a decreased risk of sarcoma formation." (Srivastav et al, 2012)
Vaccine requirements for each pet and geographic location are different. Please speak to your veterinarian about the best vaccination protocol for your specific pet(s), location, and lifestyle.