What are the Rationales Behind Rabies Vaccine Schedules?

 |  May 11th 2009  |   15 Contributions


rabies_patient
Rabies vaccination became a discussion in a dog park . . .

Is the 3yr rabies vaccine exactly the same as a 1yr rabies vaccine and just, on first use, it is only good clinically for 1 yr?

Why, in some states, is the first vaccination a 1yr only vaccination and, in other states, a first vaccination can be a 3yr vaccination if the dog is over one yr old?

Is this just because of individual state laws? This came up around a discussion on puppies and also adoption of dogs and vaccinations.

Fred
Pleasanton, CA

The Vet Blog has not touched upon vaccines in a while. Vaccines seem to be second only to food when it comes to causing controversy on this blog. Now that most of us seem to have recovered from the raw food disucssion, I think it is time to open up a new can of worms.

Tomorrow's post will discuss the use of titers in lieu of vaccines. Today, let's talk about rabies vaccines.

Rabies is among the most dreaded human diseases. According to the ultimate repository of human knowledge, Wikipedia, the disease kills 55,000 people each year. Untreated rabies has the distinction of being the most deadly disease known to mankind--mortality is 100%.

Until the advent of rabies vaccines, dogs were by far the leading source of human rabies. In areas where canine rabies vaccination is common, human rabies is very rare. Most human rabies cases occur in developing countries where pets do not routinely receive vaccines. In many of these countries, the mainstay of rabies control is mass slaughter of dogs during outbreaks. Poisoned meatballs were recently used in an attempt to control a rabies outbreak in Bali. In 2006, tens of thousands of dogs in China were killed in an attempt to halt a rabies outbreak.

Pets receive rabies vaccines to prevent the disease from spreading to humans. And given the events in Bali and China it is clear that rabies vaccination, in general, saves the lives of pets--both through prevention of rabies (which is 100% fatal in dogs and cats) and prevention of mass slaughters.

But . . . there is a highly relevant but.

In the United States rabies vaccines are administered by veterinarians to dogs (and sometimes cats) as required by law. Rabies vaccination laws are developed by state or local governments. And once the government gets involved, reason goes out the window.

Some rabies vaccines are labelled only for one year use. These must be given every year. Other rabies vaccines are labelled for three year use.

Those that are labelled for three year use are subject to the laws of local governments. In municipalities where annual rabies vaccination is required, the vaccine is given every year despite the label. In areas where three year vaccination is mandated, the exact same vaccine is given triannually.

There is no rhyme, reason, or hard science to back up any rabies law with which I'm familiar.

Rabies vaccination laws are capricious. This is especially true in cats. A case of rabies in a feral cat several years ago prompted San Mateo county, near San Francisco, to require rabies vaccines in all resident cats. Adjacent San Francisco county does not require feline vaccination. Rabies has not been reported in a cat in either county for several years (more than 100 years in the case of San Francisco).

In many places, rabies vaccinations administered to pets less than 16 weeks old are considered invalid even though there is no scientific basis for such a timeline. A puppy in Alaska recently exposed several people to the disease when it was younger than 16 weeks and had therefore not been vaccinated.

Rabies vaccinations have been linked, rarely, to cancers in cats. Some experts have suggested that rabies vaccination may trigger scary problems such as immune-mediated hemolytic anemia and ischemic dermatopathy in both species.

On balance, there is no doubt in my mind that rabies vaccination benefits pets and people. I'll take the one-in-100,000 case of ischemic dermatopathy over mass culling with strychnine meatballs (or a high prevalence of human rabies) any day. But I believe that a more rational and scientific approach to rabies vaccination is in order.

The Rabies Challenge Fund is working to investigate the efficacy of rabies vaccines and promote a scientifically validated rabies vaccination schedule for pets. Perhaps some day it, and organizations like it, will lead to rabies vaccine requirements that are evidence based.

But at this point bureaucracy is carrying the day.

Photo: This photo from the CDC illustrates why pets get rabies vaccines.

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