Today I'm continuing my interview with Dr. Ronald Schultz, Professor and Chair, Department of Pathobiological Sciences, School of Veterinary Science at the University of Wisconsin – Madison.
In part 1 of this series, Dr. Schultz and I talked about core and non-core vaccines and the difference between vaccinating and immunizing. In part 2 we continued our discussion of core vaccines and the length of protection they offer.
The next subject I wanted Dr. Schultz to talk to us about is the vaccine that is mandatory in every state in the U.S. – the rabies vaccine. I want to talk about why some states have 1-year and 3-year vaccination options.
Some of my Natural Pet clients think the 3-year vaccine is 3 times stronger. Others think it has been researched 3 times longer. So I asked Dr. Schultz to shed some light on the subject of rabies vaccines.
Dr. Schultz points out that the rabies shot is a good example of a noninfectious vaccine.
Prior to the mid-1980s, all canine and feline rabies vaccines were what is known as 'modified live.' One dose was adequate to immunize a puppy or kitten. We generally gave those vaccinations at 12 weeks or older, when there was no maternally-derived antibody left to interfere.
Back in those days, with the modified live vaccine, we re-vaccinated each year because we didn't know whether immunity lasted longer than a year.
In the late 1970s – early 1980s, some kittens given rabies vaccines in California actually acquired the disease. That situation caused the USDA to rethink the wisdom of the modified live rabies vaccine. In reality, though, rather than the modified live vaccine turning virulent, it could have been that the kittens were severely immunosuppressed. They might have been infected with feline leukemia and/or feline immune deficiency viruses, which made them susceptible to the rabies virus.
Whatever the cause of the kittens developing rabies, it was decided modified live or infectious rabies vaccines were no longer advisable. At that point, we moved entirely to a non-infectious, killed, inactivated rabies vaccine. Inactivated vaccines are not as potent as modified live products.
However, we never changed the rabies vaccination one-dose protocol, even though we changed the vaccine. My recommendation back in the mid 1970s when we made the switch to an inactivated product, was to give two doses, 2 to 4 weeks apart, and then re-vaccinate in a year. But that's not what happened.
Fortunately, the rabies glycoprotein antigen in the killed vaccine is very powerful. And an adjuvant was added, which is the case with most inactivated vaccines.
An adjuvant is a very strong immuno-stimulant, and the one added to the killed rabies vaccine provided enough boost to the glycoprotein that one dose was enough to immunize most pets for a year.
As a general rule for killed vaccines, if we go much beyond 6 to 8 weeks between the two doses, we're providing essentially no protection at all. The leptospirosis vaccine is a good example – we could never go beyond 6 weeks between the two doses, because immunity would not be established. The lepto antigen is very weak compared to the rabies antigen.
Adjuvants in Pet Vaccines
I asked Dr. Schultz to discuss the use of adjuvants in veterinary vaccines. We know that thimerosal, an adjuvant included in human vaccines, has been removed due to health concerns.
Dr. Schultz points out there are a number of substances commonly added to vaccines, for example preservatives. Thimerosal, which contains mercury, is a very effective preservative. It has been added to human vaccines for many years, however, it hasn't been used in many veterinary vaccines.
Thimerosal is a concern because it contains the heavy metal mercury, which can cause adverse reactions and is very neurotoxic at high levels. The majority of human vaccines no longer contain thimerosal, and Dr. Schultz is not aware of any veterinary vaccine that contains it.
Aluminum is commonly found in human vaccine adjuvants. It is also used in some veterinary vaccines, but according to Dr. Schultz there are many other options for adjuvants in veterinary medicine. Veterinary vaccines are actually far ahead of the curve as compared to human vaccines. There are veterinary vaccines with new technology that have yet to be approved for use in human vaccines.
Veterinary medicine has an edge over human medicine when it comes to research and application of new vaccine technologies, including adjuvants. One of the reasons for this is studies can be done on the animals for whom the vaccine is being developed rather than on, for example, rodents which is how initial studies are conducted in human medicine.
Adverse Reactions to Pet Vaccines
I next wanted to talk to Dr. Schultz about vaccine reactions. It happens, unfortunately. We see pets die from adverse reactions to veterinary vaccines.
There are different types of allergic reactions, for instance anaphylaxis and also long-term, progressive, degenerative auto-immune disease. I asked Dr. Schultz if he sees a correlation between over-vaccination and an increase in autoimmune conditions in pets.
Dr. Schultz agrees autoimmune disorders are more prevalent in both pets and humans than they were 20 or 30 years ago. He thinks there are a number of reasons for the increase, and without question, vaccines are among them. Dr. Schultz also blames the presence of intoxicants, environmental pollutants and chemicals in our world today.
He believes there are a lot of factors in the environment that in a genetically predisposed individual can trigger immune-mediated disease. He stresses the key role genetics plays in immune-mediated and hypersensitivity-type diseases.
Recommendations for Pets That Have Had a Vaccine Reaction
At my clinic, I follow a very minimalistic vaccination protocol which includes titering to insure immunity has been achieved. But when I see animals that have had vaccine reactions, under no circumstances will I continue to vaccinate. I simply won't do it.
I asked Dr. Schultz about his recommendations for pets that have had a reaction to a vaccination. He agrees my approach is the best one under most circumstances.
If the reaction is to a core vaccine and the pet is successfully immunized, Dr. Schultz recommends titering. If there's any measurable antibody in the titer, that vaccine should not be given again. If there's no antibody for one of the cores, he feels we have an obligation to make sure the animal is protected because the diseases the cores protect against are so deadly.
Dr. Schultz points out a few options, including pre-treating the pet depending on what the reaction has been, but that won't provide assurance the animal won't have another reaction.
We can also switch products and hope something in the prior vaccine that isn't in the replacement product is what caused the reaction. But that's also no guarantee there won't be another reaction. An animal may be, for example, hypersensitive to bovine serum albumin, which is very likely contained in every vaccine manufactured for a particular disease.
In terms of risks vs. benefits of re-vaccinating an animal that has had a reaction to a vaccine, I'm not personally comfortable with the risk and would not re-vaccinate due to the potential for a more severe reaction.
Dr. Schultz says we want to make sure the animal is immunized against the core diseases. If the adverse vaccine reaction is to a non-core product, which it very often is (core vaccines are much safer than non-core vaccines in terms of adverse reactions), Dr. Schultz's position to is forget about that optional vaccine, whether it's the lepto vaccine or the Lyme vaccine or injectable bordetella, for example.
And I agree. If your pet has had an adverse reaction to a non-core vaccine and your vet is still recommending it, refuse it.
Stay tuned next week for part 4 of this 4-part interview with Dr. Ronald Schultz. Next week Dr. Becker and Dr. Schultz return to the topic of rabies vaccines. The doctors also discuss the protocols they follow in vaccinating their own pets.