How Many Rabies Vaccinations Are Enough?

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As I write this, I am wrestling with living in a municipality where an annual rabies vaccination is required for all cats registered in the area. My question is, why is this the law when we know that an initial rabies vaccination followed by a booster when the cat is just a kitten will pretty much insure lifelong immunity? Even if it doesn’t, an antibody test or titer every few years will certainly show that a re-vaccination may be needed.

I briefly answered a question on this subject here, but wanted to take a moment to dig deeper and present the case that many of the laws governing vaccination requirements for pets need to be changed. Let me start by stating unequivocally that I believe that all cats need to be vaccinated. I am not some silly anti-vaxxer who thinks that vaccines are evil. Quite the contrary, I know that vaccines are an important component of the general well-being of our pets. Without rabies vaccines, the disease would be much a more prevalent problem than it actually is in most parts of the world.

Unfortunately, all the lawmakers really know about it is that the vaccine works under current laws. But when we take a look at the science behind the rabies vaccine, we see some good news and some bad news.

The good news is, as stated above, the vaccines work. We do not have major outbreaks of rabid pets in urban areas across the country. In fact, we have very few reported incidents of rabies at all among domesticated animals.

Wildlife has accounted for > 90% of all rabid animals reported in the United States since the 1980s.
— Journal of the American Veterinary Medical Association

You can read the full report, which focuses on the 2017 calendar year, HERE. It states that in 2017, “Of the 4,454 cases of animal rabies, 4,055 (91.0%) involved wildlife species.” Of the 399 cases of domesticated animals reported with rabies, 276 were cats and 62 were dogs. With >99% of human deaths from rabies worldwide coming from human contact with rabid dogs, it’s safe to say that we’re well protected from the disease in the US. The major cause of concern here is the transfer of the disease from wildlife to our pets, but that clearly isn’t happening frequently. I would hypothesize that most of the cats and dogs who contracted the disease did so because they were not vaccinated at all.

The bad news is that the success we’ve had in minimizing the impact of rabies has come largely from a policy of over-vaccination of pets in a large hammer approach. While this has truly been effective, we’ve seen some negative consequences among the cat population. Potential side effects include injection site tumors (sarcomas), persistent vomiting, diarrhea, hives, swelling, breathing difficulty, and collapse.

Cats are especially susceptible to injection site sarcomas. These are cancerous tumors that develop at the location of the injection (usually between the shoulder blades) and which can develop weeks, months, or even years after the injection (ref. AVMA). Cat-friendly veterinarians can choose to use vaccines such as Purevax without an adjuvant to help minimize this problem. They may also keep track of injection locations and rotate locations frequently, keeping to the extremities in case a tumor were to develop.

The problem is that current rabies vaccination laws were mostly written during the 1970s. When the laws were written, they were VERY effective at curbing a problem that presented great risk to an exploding population of pets and their caregivers. At that point, most municipalities closed the book on this particular set of laws and have not addressed them since, taking a “if it’s not broken, why fix it?” attitude. Well, many veterinarians and researchers like Dr. Ronald Schultz, disagree and recommend change.

Dr. Schultz is the head of the pathobiological sciences department at the University of Wisconsin, Madison, School of Veterinary Medicine. His specialty is veterinary immunology, and he states that the core vaccines needed by cats are feline panleukopenia, feline calicivirus, feline herpes virus, and rabies” (ref. YouTube interview). He states that every cat should receive these as a kitten. The remaining vaccines are considered non-core or optional.

We do a lot of vaccinating and sometimes don’t do very much immunizing.”
— Dr. Ronald Schultz

Dr. Schultz recommends that a kitten receive core vaccinations at 8, 12, and 16 weeks. Then, two or more weeks later, the kitten should be tested with an antibody titer to make sure that the vaccinations have induced an immune response to panleukopenia in particular. This can weed out non-responders and establish protective immunity. Those pets are now protected for life. There is no reason to continue boosting vaccines because it doesn’t improve the immune response. He only recommends re-vaccinating every three years if a titer isn’t performed.

“If you don’t do that antibody titer two or more weeks after the last…shot, then we’re recommending that you re-vaccinate in a year…and then after that, what we recommend is three years or longer, which means not more often than three years. Now, that’s a very conservative number in that most of those animals will be protected for life, so giving the vaccine every three years may not be necessary…Some clients…will go with titers to actually determine whether or not they need a so-called booster.” He goes on to explain that there are various methods of titering and that the numerical results given “don’t mean anything as long as they’re positive.”

In regards to the rabies vaccine, Dr. Schultz says that in the 1980s, it was suggested that the modified live rabies vaccines used back then be administered annually because no one really knew how long the immunity lasted. When some kittens contracted rabies from the modified live vaccine, there was a shift to the non-infectious, inactivated rabies vaccines. He states, “We never did change the vaccination program. We changed the vaccine, but not the program.”

His department at the University of Wisconsin is currently conducting a study to extend the legal length of time between re-vaccination from a maximum of three years to a maximum of seven. The fact is that in most animals, immunity will last a lifetime, but the current need is for proof that our pets’ immunity lasts much longer than was previously believed. The difficulty with conducting these studies is that their duration has to be at least as long as the term being studied. They settled on a study length of seven years to reap the benefits sooner rather than later. If a study of feline immunity were to cover a cat’s lifetime, it could last 20 years or more and be of little benefit in changing the laws in the short term.

For this reason, it’s imperative that the laws get changed to require antibody testing instead of requiring vaccinations. Municipalities need to accept titer test results in lieu of re-vaccination. The Kansas State Veterinary Diagnostic Laboratory has come up with a screening test to determine if patients need vaccine “boosters”. The American Holistic Veterinary Medical Association is supporting them in their effort, and we must as well.

The requirements that cats be registered and vaccinated according to current laws means that many cats will never receive their very necessary vaccines when they’re kittens. The law’s very existence even dissuades some people from visiting a veterinarian on a regular basis.

Dr. Schultz said, “The animal that’s not getting vaccinated, whether the requirement is annual or every three years, won’t get vaccinated. It’s just a penalty for the compliant…owner and they’re actually potentially causing harm to their pet because they’re willing to follow the law, whereas the rest of the people who are not vaccinating at all are creating the problem and they’re not going to follow the law whether it’s one year, two years, or three years.”

Please reach out to your lawmakers and let them know your concerns about the current laws governing local vaccination requirements for your pets. It’s important to approach them in a calm and businesslike manner and to address them properly in order to be more persuasive, but you should also be firm with a clear expression of what you’d like to see happen. I’ve prepared a sample letter here that you can download to copy and edit to your liking.

You can find the contact information for your local legislators at USA.gov. I recommend that you print and mail your letter the old fashioned way in order to get more attention. It’s just too easy for lawmakers to ignore emails or dismiss them. Paper letters are difficult to ignore, especially if they start stacking up.

The Rabies Challenge Fund is currently supporting Dr. Schultz and his ongoing immunity study. I encourage you to support them in their stated goal of determining the duration of immunity conveyed by rabies vaccines in order to influence future changes to animal vaccination laws.

-Tom