Vaccination protocols: Immunology 101

[Dennis Thomas, DVM]

As you probably know, there is a lot of information going around about vaccinating pets. Why is this happening? Why am I getting conflicting information from my vet and others? Why does one vet tell me something and another tell me something else? What should I really be doing in regard to vaccinating my pet?

I am posting this information in hopes that it might answer some of these questions. What you decide to do is ultimately up to you. Your vet is there to help you make decisions and offer advice, but remember, not all vets have all the information. Sometimes, the old, "If it ain't broke, don't fix it" motto is what we rely on.

Point number one: Most vaccines are produced when there is an outbreak of a new disease. Whether it is canine distemper, parvovirus, lepto or feline leukemia, drug companies react to new diseases in order to quell an outbreak. I have been in practice for over 35 years and I remember most of the outbreaks that initiated vaccine production. When I was a senior in vet school, we had the first outbreak of parvovirus. It killed so many dogs and puppies that we were using cat vaccines in hopes that we would find a way to protect them against this horrible virus. When the drug companies came out with an effective vaccine, the disease was easily controlled and now we see very few cases of parvovirus and usually the few we see are in areas that have poor immunization protocols. I also remember when feline leukemia showed itself. It was so bad that every sick cat that came into the clinic was tested for FELV before anything else because if the test was positive, the cat would be put to sleep because there was no successful treatment. We would average about 10 cats a week that would die from leukemia. Today, it is rare to find a cat with this disease. And, the list goes on and on.

What we need to remember is that in the face of an outbreak of a new disease, the intent is to find a protective vaccine as soon as possible. Not only for the protection of the animal, but the first company to release a vaccine usually make the big bucks because people were waiting in line. What this meant was that there was very little attention directed at possible side-effects and certainly nothing in regards to long-term protection and side-effects. Everyone was content to stay with the status quo and this went on for years and years.

Point number two: How does immune protection work?
In the real world, most puppies and kittens receive what is called maternal antibodies from their mother. Immunologists call this passive transfer of immune protection. An example would be breeding a Labrador that had been vaccinated and had developed protective antibodies from the vaccines. Theoretically, these maternal antibodies will transfer to the puppies in utero and in the colostrum when nursing. Ultimately, these maternal antibodies would protect the puppies in the case of an exposure to any viruses that the mother had been protected (DHPP, Lepto, Rabies, etc). We know that when the puppies reach 12 weeks, the maternal antibodies will have cleared the puppy and the puppy will no longer be protected. This is why the Rabies vaccination (given once as a puppy) is always done after 12 weeks of age. Again, in theory, any puppy that is given a vaccine up until the age of 12 weeks, the maternal antibodies will prevent the puppy from reacting to the vaccine, hence negating any benefits. Some drug companies try to circumnavigate this but there is no evidence that it works. Why then do we vaccinate puppies before the age of 12 weeks if there is essentially no benefit of doing so? Because all of the puppies and their mothers don't read the theoretical book. Research suggests that about 5% of the puppies do not receive adequate maternal antibodies. This might come from the mothers side or the puppies inabilities. So, we give vaccines in the event that your puppy is one of the 5%. There is no way to test at this time to determine if the individual puppy has received maternal antibodies.

Point three: If it ain't broke....
The standard protocols for vaccinations remained status quo for many years. There was no real reason to make a change. Most of the pets being vaccinated were protected, the horrible diseases seemed to be in check and life was good. About 25% of a veterinary hospital's gross income was from annual vaccinations plus anything else that was picked up during the exam (need for dentals, ear infections, lump, etc.). Life was good. Then, some veterinarians started noticing that there were diseases that were dramatically on the rise and most of those had to do with immune-mediation (autoimmune). The AVMA (our national veterinary association) decided to look into these and started looking at anything that could affect the pet's immune system. Obviously, immunizations were first on the list. The AHVMA did a study using research done by three veterinary colleges, individually assessing the long-term immune protection of the vaccines commonly used. They hoped to find out if we were over-vaccinating our pets.

All three universities came up with the same results. Yes, we were vaccinating more than necessary. Most vaccines that were being given had much longer protection than the one-year recommendation. Remember, the drug company had a one-year label on the vaccines and the vets were going by the drug companies requirements. After a lot of deliberation between our national associations (AVMA, AAFP, AAHA) they established guidelines for vaccinating our pets. Basically, the guidelines stated that pets should not be given their core vaccines (DHPP and Rabies for dogs and FVRCP and Rabies for cats) no more frequently than once every three years.

Now, this rocked the veterinary world. The status quo had been changed and veterinarians don't like changing the status quo. Many veterinarians decided that would go to the three-year protocols and many did not. The national associations do not have regulatory function. They can only make suggestions. There was a loophole that was used by the vets that did not want to go to the new protocols. The vaccines had a one-year label. That meant that the drug company would only stand behind a one year protocol in case of an outbreak of the disease. No veterinarian would go against that as it would be too much of a potential for lawsuit. That excuse lasted about a year until the first drug company came out with a three-year label. Remember, first company makes the big bucks. Now, there is no such thing as a one year rabies vaccine, although some states still require rabies to be given annually.

The big factor was the realization that about 25-30% of the clinic's gross income was based on annual vaccinations. The average established veterinary clinic was working on a net of about 25% of the gross. It doesn't take an accountant to scare the bejeebes out of a vet when they are potentially looking at no net income. This is why the latest research found that about 41% of the vets in the US still vaccinate annually even though the recommended guidelines for a three-year protocol has been out for more than 10 years.

Point four: It is broke....
Over the past 10 or so years, there has been a lot of studies about the potential for harm by giving vaccines. There has been studies done by renowned research veterinarians funded by grants (not drug companies) that indicate that vaccines do not come without potential problems. Many of them were blatant. One example is the use of Thimerosal as a preservative in rabies vaccine. Thimerosal is a chemical preservative that has been used for many years in both veterinary and human vaccines. Thimerosal contains 48% mercury and mercury is a known toxin in animals and humans. The government has prohibited its use in human vaccine but it has not done so inn animal vaccine. Most of the rabies vaccines manufactured in the US still contain Thimerosal. There are two companies that make Thimerosal-free rabies vaccine. Most veterinarians are unaware of the problem with this preservative and do not know enough to buy rabies vaccine that does not contain this preservative. Here in Spokane, WA, we called most of the veterinary clinics in town to find out if they had Thimerosal-free vaccine. We did not find one clinic that had one. Most did not know anything about the vaccine. This is just one potential problem that is often overlooked.

The fact is that any vaccine has the potential for harmful side-effects, both acutely and long-term. There is absolutely no reason to be giving vaccinations more frequently than is recommended by established guidelines. We can no longer pretend that there is no danger in doing this. We are all pet caretakers that want to do what is best for our pets. We need to empower ourselves by taking the time to find information about the pros and cons of vaccinating and make decisions based on our beliefs. Most veterinarians are not trying to give you bad information. They believe what they believe because it has worked for them. But, this does not mean that it is always fact. Please go to the AVMA website for their vaccination guideline recommendations.