HOW DO VACCINES WORK?
And Why Do I Need to Give My Pet So Many?
So it only took 5 posts for me to fall behind on my schedule to post every week. However, I do believe that my excuse is both timely and topical. I usually try to complete my posts on Fridays, but last week, at the urging of my wife and the recommendations of the CDC, I went to get my Flu Shot. Yes, I believe that what is good for the goose is good for the gander (your pet being the goose and I'm the gander in this post). So, while I should have been teaching everyone about the importance of vaccines, I was off getting vaccinated. Now, along with a very aggressive hand washing policy, I have done everything that I can to protect myself against Flu this season. I chose to get immunized because I am at risk for infection, research shows that the Flue vaccine is relatively effective in preventing infection vs not vaccinating, and vaccines in this country are generally safe so that the risk and expense is far outweighed by the benefit.
What are vaccines?
Vaccines are biological products that are designed to stimulate the immune system to generate a response to protect the patient from future infections. Wow, reading that back I realize that it was quite the mouthful. Let's look at it another way. Our pets' immune systems are designed to ward off dangerous infectious agents. When their body is invaded by a bacteria or virus, the body responds in a variety of ways, the most vigorous of which is to produce antibodies and special killer cells to destroy the infection and restore the body to a state of health. In addition, the immune system tries to establish some memory, so that if the same infection comes along again, it will be primed to have a quicker response, possibly killing off the infection before the host becomes sick. The duration of this immunity varies, depending on the type of infection and the health of the host.
Vaccines are designed to stimulate the immune system, just like a dangerous infection, but without the risk. The body produces circulating antibodies and memory cells to keep us healthy in the face of potentially serious infections.
There are several types of vaccines and modifications of each type but here is a summary.
- Modified Live Virus Vaccines. (MLV). These vaccines contain living bacteria and viruses (OK sometimes mycoplasmas as well but why confuse the issue). These infectious agents are attenuated, that is weakened so that while they can trigger an immune response, they don't cause disease. The advantage to MLV products is that since the virus is alive, it will reproduce in the host, allowing a smaller number of virus particles to be injected. This minimizes vaccine reactions while maximizing immune stimulation. The potential downside is that attenuated vaccines are best for viral diseases (with the exception of that nasty nose drop Bordetella vaccine) and there is a small chance that the virus can revert to the wild state and cause illness.
- Killed vaccines use dead viruses or bacteria (killed bacterin). There is no chance for reverting back to the wild strain, however, since the antigen (bacteria or virus) are not reproducing in the host, a larger number must be injected. In addition, these vaccines often contain adjuvents, which are chemicals to stimulate the immune system to give a better response.
- Vectored vaccines. In these vaccines, the antigen is incorporated into a harmless virus, such as canary pox. The virus and the antigen are injected into the pet and the vector reproduces in the patient. Since it is harmless for that patient, there is no risk of disease. Since the antigen load increases in the host, there is no need for an adjuvent
- Sub unit vaccines. In these vaccines, only portions of the infectious agent are used to stimulate the immune system. Some of these are adjuvented, some are not. Most only give shorter term immunity, usually around a year.
Which Vaccines Does My Dog or Cat Need?
There are many different vaccinations available in all sorts of combinations. Not all pets need all vaccines for all diseases. You should have a conversation with your veterinarian to decide which diseases your pet is at risk of catching and then picking the appropriate vaccines to keep him/her healthy. We recommend an annual life style assessment for all of our patients to help us to determine the best vaccination program for each individual. We follow the American Hospital Association and American Association of Feline Practitioner Guidelines and divide our vaccines into core and non core.
- Canine Core Vaccines (Vaccines every dog should have in our area), We include Distemper/adenovirus/Hepatitis/Parainfluenza/Parvo/ (5 in 1, or DH2PPV), Leptospirosis (most dogs), Bordetella, and Rabies.
- Canine non Core Vaccines include Lyme and Influenza. Leptospirosis for certain toy breeds.
- Feline Core Vaccines include Feline Viral Rhinotrachietis/Calicivirus/Panleukopenia (3 in 1 or distemper), Rabies and Feline Leukemia for kittens.
- Feline Non Core Vaccines include Feline Leukemia for adult cats not at risk, chlamydia, and FIP.
We have been using an extended vaccine protocol for both dogs and cats for years and recommend that you speak to your veterinarian about how long each vaccine will provide protection for your pet. Some vaccines need to be given every year, others not as often. In general, the frequency of rabies vaccination is governed by state law.
The bottom line is that all of our pets are at risk for infectious disease. I have seen puppies and kittens suffer horribly and die of preventable illnesses. I have witnessed the chronic debilitation of pets that were infected with disease causing agents that could easily have been eliminated from their bodies before causing disease. Prudent vaccination is definitely a cornerstone of an effective preventive health program for all of our pets.