Vaccine and Vaccinations
How they Work
This article is meant to inform you and your veterinarian of research results which might be useful in determining a vaccination program for your pet. It is educational in nature and is not intended as veterinary advice. The author cannot be held responsible for any unfavorable results from the use of this information. Readers should seek professional veterinary advice for any health decisions involving their pets. I am not a vet.
The Immune System:
The immune system functions to identify and attack foreign substances; specifically mutant cells, foreign bacteria, fungi and viruses. When attacked by an antigen ( a substance that causes the production of antibodies when introduced directly into the body) the immune system goes into immediate action. It first identifies the specific antigen which has begun an "invasion" and then begins to use various abilities. The immune system has the ability to distinguish between different antigens; the ability to remember how to identify foreign antigens; the ability to locate and move defenses against the foreign antigen and the ability to replicate components in the immune system to increase the immune response to those foreign antigens.
There are four cell type components that make up the immune system. Most commonly known are the "white blood cells" (T-cells), phagocytes, B-cells and NK-cells. These four components together (or separately) fight foreign substances in the body.
T-cells are the "master switch" of the immune response and are responsible for turning on and off the entire system.
Phagocytes are produced in bone marrow and function by surrounding and ingesting foreign material.
B-cells are responsible for producing antibodies. There are two types of B-cells: plasma which is short-lived but produces antibodies specific for that particular antigen; and memory cells which are ready to respond to a second or subsequent infection by the same antigen. This phase of the immune cascade is where immunity to various diseases is developed. This phenomenon is the basis for giving a primary vaccine followed by a booster shot at a later date.
NK-cells' primary function is to attack cancer cells.
When the immune system encounters a virulent bacteria or virus for the first time it synthesizes specific agents to deal with the infecting organism. Once the immune system has learned to produce a specific antibody it then produces the proper amount of antibody as needed. If these learning and production processes occur quickly enough, then the disease can be overcome. The next time the immune system encounters an organism which it has previously met, it "remembers" what to do to combat the infection. The process becomes much more rapid thus either reducing the severity of the disease or preventing the disease altogether. The "body" is said to have "acquired immunity".
Vaccines induce immunity by use of the same principle. Vaccines bear some similarities to the disease agents. A vaccine introduces the body to altered antigens of a disease to provoke a defensive response. The body acquires immunity without suffering the disease.
Viral and Bacterial Diseases:
There are several types of viruses and bacterial diseases known to infect dogs. Through literature, books and the internet ... information on specific diseases can be obtained. Dogs are continually exposed to a number of infectious agents throughout their lives. During a narrow window of time in puppyhood after the maternal antibodies inherited from their dam no longer provide protection is when dogs are most vulnerable to infection. This is the period before their own immune systems can produce adequate quantities of antibodies to fight disease. Breeders need to be alert to any sign of illness during this period.
What are vaccines?
Vaccines are bio-medical products made from micro-organisms. Their purpose is to induce the body to build up immunity to infectious agents by learning to synthesize "antibodies". The virus contained within these vaccines is no more, no less than a DNA or RNA strand wrapped in a protein coat. These strands cannot reproduce themselves. Dogs will be immune to the original strain which they have been vaccinated against. However, because viruses and bacteria continuously evolve into new strains there is no 100% guarantee of immunity against these new strains. Dogs may also not acquire immunity even when vaccinated if they have health problems.
Types of Vaccines:
The two most common types of vaccines are: killed virus and modified live virus. A third type, recombinant DNA, will not be discussed.
This is a virus totally inactivated either through irradiation, heat or various chemicals that is used as the basis of a vaccine . The main advantage of this type of vaccine is also the chief disadvantage. Since this virus is unable to replicate in the host, it is incapable of reverting to a virulent form and thus is considered to be much safer than attenuated vaccines. The disadvantage, however, is that this results in a weakened response by the immune system for a shorter period of time...which may then produce less than perfect immunity. Also, allergic responses to the preservatives used in this type of vaccine can cause abscesses and swelling at the injection site. Killed vaccines must be given more frequently than other types of vaccines in order to invoke an immune response.
Modified Live Virus:
The modified live virus approach is designed to establish the virus in a host without causing the disease. Modified live virus (MLV) vaccines are cultures of living organisms and contain no preservatives. One disadvantage of MLV vaccines seems to be their immuno-suppression of the inoculated animal. An immuno-compromised animal may not withstand the insult of the given MLV and develop the disease against which it was immunized.
Do's and Don'ts of Vaccines
Never vaccinate a pregnant bitch ... especially with modified live vaccines.
Antibody titer levels should be checked prior to being bred. Spontaneous abortions, reabsorption and birth defects have been documented in medical literature.
Vaccination of Puppies:
Puppies should be vaccinated. Researchers are unclear just when the maternal antibodies cease and a puppy's own immune response begins to respond independently. Maternal antibodies are obtained within the first 24/72 hours after birth through the colostrum and first milk. (Colostrum is the fluid secreted by the mammary glands just before and after whelping). The passively acquired maternal antibodies depend on the original titer levels of the bitch and protect the newborn puppy. These same maternal antibodies however block the mounting of an immune response to a vaccine antigen. Because a higher titer level is needed to prevent disease than to block an immune response, there is a window of opportunity during which the puppy is unprotected. The actual number of shots is not what is important, but finding that window of time between the maternal antibodies ceasing and the immune response of the puppy beginning.
Age of Puppies:
Ideally, the first shot should be delayed until the puppy is at least 6 weeks old. Research has indicated that receiving shots under the age of 4 weeks has serious side effects. The use of MLV in this age group has sometimes caused encephalitis in puppies and cardiomyopathy (heart trouble). Research is unclear as to when the last vaccination series should be given, but current thinking suggests that a puppy should be at least 22 weeks old for a final vaccination series.
Many veterinarians recommend a minimum final dose in the following vaccination series: Canine Distemper 14 weeks, Infectious canine hepatitis virus 12 weeks and canine parvovirus 22 weeks.
Spacing between shots is also a much-debated issue. Research has proven that vaccines given fewer than 10 days apart can cause a suppression of the immune system to occur. Most researchers agree to a three to four week spacing of shots.
Do not vaccinate sick or immune-compromised puppies or adult dogs.
While genetic predisposition and allergic responses may contribute to vaccine failure, the one immediately addressable condition that can influence immune response is the nutritional status of a puppy. Poor diets are most likely a major contributor to vaccine failure.
The recent development of vaccine induced sarcomas in cats has lead to the question of how much and how frequently we should give shots. Some veterinary associations are now recommending re-vaccination every three years. Still others are recommending that combination series be broken down to single components series shots. Research regarding the length of immunity of vaccines is needed. In the meantime, veterinarians and owners need to be aware of the serious risks involved in over-vaccination.
Prior to the Parvo outbreak in the late 1970's, vaccinations were not given annually. Rapid development of a vaccine for Parvo brought about changes on how shots are given. Vaccinating dogs became more frequent, especially in puppies. Unfortunately, vaccination procedures led to the development of combination shots and the giving of annual vaccinations. No one expected that a normal healthy dog could develop immune problems from over-vaccination.
What are titers?
A titer is a test used to measure the presence and quantity of antibodies in blood against a particular type of tissue, cell, or substance. Blood is drawn from a vein and levels of antibodies in the blood are measured. The antibody level in the blood is a reflection of the body's past experience or exposure to an antigen, or something that the body does not recognize as part of itself. Every living cell has different protein markers on its surface called antigens and the body's immune system identifies those cells that are not part of its structure by those surface proteins. The test will indicate that the body has come into contact with a particular antigen.
This procedure is used in research and in the development of vaccines to prove their efficacy. Just recently, veterinarians have begun to use these tests as a means to check the level of immune system antibodies in canines. Owners are encouraged have titers in place of giving annual shots.
Vaccines and the companies who make them.
Research indicates that canine distemper vaccines are effective up to 10 years. It is important to realize that not all vaccines and companies who make them are created equal. Researchers are just now beginning to learn more about the duration of immunity in current vaccines on the market. When looking at products, it is best to look at the research done on the length of immunity provided by the product. In the United States, vaccine companies are not required to prove the length of duration of the product for licensing. This hints at the importance for both vets and pet owners to understand the value of researching a product prior to use.
In studies done, first series shots are usually only 50% effective. Some vaccines were shown to give 80% immunity on the first shot Lepto is NOT recommended to be given until AFTER 12 weeks of age.
Combination Vaccines vs. Single Series Shots.
Combination vaccines are designed to prompt an immune response to several diseases at once. 5 in 1 shots or 7 in one shots are very common. Single dose shots are designed to invoke an immune response to one disease. Which is better? There has been no conclusive evidence that one is better than the other. One University has suggested that vets alternate single series shots every year instead of combination shots every three years.
A good article to read is "Vital Vaccinations" from DogWorld issue February 1996. A copy of this article can be obtained by contacting DogWorld.
An article written in the DVM NewsMagazine of Veterinary Medicine May 1998 issue is "Some recommended changes in vaccine protocol for dogs".
Some of the highlights of this article are:
1. There is definite proof of sarcomas (cancer) in cats being caused by vaccines. 2. The need for more studies to determine the safety of killed and multivalent vaccines as well as continue research regarding the length of immunity. 3. Dr. Schultz is currently doing research showing the combinations of various components in vaccines have caused adverse reactions in dogs as well as increase of anaphylaxis. 4. Prior to the outbreak of parvovirus, vaccines were NOT given every year. 5. Research has indicated that distemper vaccine is effective up to TEN YEARS. 6. Research shows that dogs do not medically benefit from receiving annual vaccinations and can lead to medical problems or severe reactions. 7. People should consider vaccinations as a medical procedure and should be given "as needed".
It will be interesting to see how the drug companies respond to this new research as these companies have spent millions of dollars developing combination vaccines. In Europe, it is recommended shots be given every four years.
Please note, this article is Not advocating no shots, only advocating researching the products and discussing with your vet the alternative methods to help you decide which vaccination program would work best for you and your pet.