Titre testing can be confusing
By Dr. Moira Drosdovech
Pawsitive Veterinary Care
Fortunately for our pets, the major veterinary associations, in particular the American Animal Hospital Association, have recommended boosters no more frequently than every three years and only for those diseases that are relevant in the area the pet lives. This is great news as it means that there will be far less opportunities for adverse vaccination reactions, which are increasingly being recognized by our scientific community.
The question for many veterinarians and pet owners is: how often should we re-vaccinate after the initial puppy or kitten vaccines? In the past, annual re-vaccination has been recommended as a "better-safe-than-sorry" approach, simply because little was known regarding the duration of immunity. With increasing knowledge of the potential dangers of unnecessary frequent vaccination, and the development of standardized titre testing, this philosophy is being re-visited.
A commonly held belief based on observations as well as scientific studies is that vaccinating every three years is still excessive, as the immune system has a ‘memory’ that helps it to recognize foreign invaders it is primed to defend against. This memory is active for years and possibly for the life of a pet.
The immune system mainly consists of B-cells and T-cells. B-cells are the cells that make the antibodies against viruses, bacteria and other foreign proteins and their response is called the Humoral Response. T-cells are the cells that are the first on the scene, so to speak, and help to clear the body of foreign proteins as well as ‘present’ these proteins to the B-cells. This system is known as the Cell-mediated System. Without T-cells, your body is in big trouble, as people with AIDS soon discover.
A titer is a reflection of the quantity of circulating antibodies (immunoglobulins) to a given antigen (in this case, an organism). The immunologic memory is not dependent upon titers, nor do titer levels always accurately indicate the immune status.
The B-cells retain the ability to produce antibodies toward a given antigen for quite a long time, usually for life. Upon re-exposure, they can produce antibody within forty-eight hours or less. As a consequence of this capability, there is no need for the body to expend the energy needed to maintain circulating antibodies.
A low or absent titer, therefore, does not mean the body is unprotected. The body may simply have cells ready to act, like firefighters playing cards until they are needed. When booster vaccines are administered, antibodies destroy the vaccine particles before they can augment the immunity, and nothing is accomplished.
A titre of 1:5 or greater (larger number to the right of colon) indicates that the pet has mounted an antibody response to the virus being tested. As long as the pet is healthy and immunocompetent, the virus will most likely be cleared. It is irresponsible to say the titre is “protective" since this may be perceived as an implicit guarantee of protection against disease. Vaccination is no guarantee of protection and neither is a positive titre.
Because vaccines carry with them a risk of adverse reactions, talk to your vet about what is absolutely necessary for your pet. For instance, I recommend that my clients with indoor only cats never vaccinate as the risk of them becoming infected with a virus we vaccinate against is next to nothing.
Reactions to vaccines seem to fall into two groups: there may be an allergic reaction within perhaps 48 hours, or an immune system reaction which may be some weeks or even months later. Because of the time lag, these later reactions are often not associated with the vaccine.
Some researchers believe that vaccines may confuse or damage the immune system, either by causing the body to over react to normally harmless substances (allergies, esp. flea allergies, skin problems), or to produce antibodies to itself (autoimmune disease). Response to things the body should reject may become slow, eg. common virus, fungi, parasites, thereby increasing susceptibility to acute infections such as ear infections, chronic worm or flea problems.
Also possible after vaccination are behaviourial changes. I recently treated a 15 month old dog for what is known as Rabies vaccinosis in homeopathic veterinary circles. He had all his initial puppy boosters including Rabies and was re-vaccinated for Rabies at 14 months old to enable him to cross the border to the states.
Within two weeks of the vaccine, he was a different dog. Once the daycare “clown”, he became snappy with the other dogs and he no longer wished to work at his agility training. We treated him with one homeopathic remedy administered twice and by the next day, he was once again his usual self.
This case serves to illustrate that vaccines can have a profound and very deep effect on pets (and people) and should be used with the utmost caution.
Vaccine titre tests provide an alternative for pet owners who have concerns regarding the potential for adverse side effects associated with annual vaccination. These tests are now being accepted at many progressive boarding kennels, agility clubs , obedience classes, pet therapy societies and others.
Many people who are trying to reduce vaccination are interested in using "titers" as a test to measure whether or not their dog is still immune to a disease. They often speak of titers as showing "high" or "low" immunity, or of "having to" re-vaccinate when a titer is low. While there is not a tremendous amount of research on titers in dogs, I think it's fair to say there is quite a bit of misunderstanding on the part of pet owners, and even many veterinarians, as to what a titer test does or does not tell us.
A "titer" is a measurement of how much antibody to a certain virus (or other antigen) is circulating in the blood at that moment. Titers are usually expressed in a ratio, which is how many times they could dilute the blood until they couldn't find antibodies anymore. So let's say they could dilute it two times only and then they didn't find anymore, that would be a titer of 1:2. If they could dilute it a thousand times before they couldn't find any antibody, then that would be a titer of 1:1000.
A titer test does not and cannot measure immunity, because immunity to specific viruses is reliant not on antibodies, but on memory cells, which we have no way to measure. Memory cells are what prompt the immune system to create antibodies and dispatch them to an infection caused by the virus it "remembers." Memory cells don't need "reminders" in the form of re-vaccination to keep producing antibodies. (Science, 1999; "Immune system's memory does not need reminders.") If the animal recently encountered the virus, their level of antibody might be quite high, but that doesn't mean they are more immune than an animal with a lower titer.
Dr. Donald Hamilton, a holistic veterinarian and author of Homeopathic Care for Cats and Dogs: Small Doses for Small Animals, compares antibodies to fire engines. Just because the fire engines aren't racing all over town all the time, and the fire fighters are back in the firehouse, sleeping, eating or playing cards, doesn't mean they aren't ready to jump in their trucks and head to the fire when the alarm sounds.
So what does a low or zero titer tell you? Nothing much. A high titer is strongly correlated with either recent infection or good immunity, but the opposite isn't true. You can use a titer test about two weeks after vaccination to determine if the vaccination was effective in stimulating an immune response (in other words, if the animal was successfully immunized from the vaccine), but testing that same animal's titer years down the road doesn't really tell you anything new.
The only other uses for titer tests in my opinion are to check immunization status on dogs with an unknown history, to provide documentation for legal purposes such as travel, or licensing in areas that accept rabies titers in lieu of rabies vaccination, to satisfy curiosity, or to provide peace of mind for pet owners. However, for every person who has his or her mind relieved by finding his or her dog "has a titer" to a disease they were worried about, there is someone else who now thinks his or her dog or cat is "unprotected" against a disease to which they are most likely really immune.
