When should I vaccinate my puppy? Does my dog need to be vaccinated every year? These are common questions about vaccinations for which there are no easy answers. Deciding which vaccines to get, when to get them, and how often to booster them depends on a number of variables, including the safety and effectiveness of the vaccine, what your dog’s chances are that it will get the targeted disease, and the seriousness of the disease. Although this article provides guidelines to help you make these decisions, it is important to always check with your veterinarian first.
The role of vaccines
Why do we vaccinate our dogs in the first place? The main reason is to protect a dog from disease. The vaccine is designed to stimulate an immune response to protect the dog if it is exposed to disease. Even if your dog stays close to home, it is possible that you could bring a disease home on your shoes or clothing. And if your dog does leave its home turf, the risk of exposure increases.
Some viruses, such as parvovirus and distemper, are amazingly hardy and can last in the environment for a long time. Vaccination also protects the general population of dogs, and, in the case of diseases that are spread to people (zoonotic diseases), it may protect the human population as well. While thousands of people die of rabies worldwide, human deaths due to the rabies virus are rare in the United States because of animal control and rabies vaccine requirements for pets. Vaccines do not calm a dog or change its temperament; they protect it against specific diseases.
Core vs. noncore vaccines
The American Veterinary Medical Association and the American Animal Hospital Association have developed a set of guidelines for the vaccination of dogs. Included in these guidelines are four “core” vaccines that they recommend for all dogs in the United States, based on the infectious nature of a disease, the severity of a disease, and the effectiveness of the available vaccines. These core vaccines include rabies virus, canine distemper virus, canine parvovirus, and canine adenovirus-2 (which protects against canine hepatitis ). Distemper, parvovirus, and adenovirus are commonly combined in a single shot. Rabies is always given separately.
Vaccines that are considered “noncore” include those against leptospirosis, kennel cough (bordetella bronchiseptica and parainfluenza), Lyme disease (borellia burgdorferi), and canine influenza. These vaccines are recommended if your dog lives in or travels to areas where the diseases are more prevalent or if your pet's lifestyle brings it into contact with carriers of the disease. Dogs that live, hunt, or hike in some wooded areas may be more at risk of Lyme disease or leptospirosis. Dogs that travel to dog shows, are groomed outside the home, play at dog parks, or otherwise come into close contact with other dogs may be more at risk of kennel cough and influenza. Different regions of the country have different disease prevalences. Canine influenza is an example of a fairly recent disease for which a vaccine has been developed. It is important to discuss these factors with your veterinarian when determining which vaccines your dog should receive.
Timing of vaccines for puppies
Most vaccines require a series of shots when a puppy is young, starting at 6 to 8 weeks of age. When the pup is a newborn, it gains passive immunity against diseases from its mother in the first milk, or colostrum. If the pup is first vaccinated when these antibodies are at a high level, the vaccine will not be effective, but if the pup isn’t vaccinated and the maternal antibody level falls, the pup will be unprotected. Because the antibodies disappear at a different rate in every dog, a series of several vaccines are given three to four weeks apart until the pup reaches 12 to 16 weeks of age. In all, a pup will receive a series of three to four different shots depending on the age when the series is started and the specific vaccines given. It is then important that the puppy receive another vaccine against each disease a year later. A single rabies vaccine is given at 3 to 4 months of age and then repeated one year later.
Timing of vaccines for adult dogs
If an adult dog has never been vaccinated or has an unknown vaccine history, a series of two shots three to four weeks apart, is recommended for most diseases. Once the initial vaccine series has been completed for the adult or puppy, the core vaccines usually need to be boostered every three years. This is a change from previous recommendations that were based on the belief that the vaccines needed to be boostered on an annual basis. Further tests have shown that this usually isn’t required and that the immunity from the vaccine will last several years. Many of the “noncore” vaccines, such as for bordetella and Lyme disease, still require yearly or more frequent boosters, so it is important to follow the manufacturer’s guidelines on all vaccines and to speak to your veterinarian about what he or she recommends. It is also still important to have your pet examined yearly by a veterinarian to be sure it is healthy and to ask questions you might have.
While most vaccines are safe, there are times when your dog can still become infected with a disease or may have a reaction to the vaccine itself. Vaccine failure can occur due to manufacturing problems (very rare because of the safeguards built into the process) or to handling failures before it is given (more common). Most vaccines need to be kept refrigerated and then mixed properly before administering. Ordering vaccines over the Internet or getting them from an unreliable source increases the chance that handling errors might occur in transit. It's also possible that a dog may not mount a good immune response to a single vaccine due to an inadequate immune system.
The other concern with vaccinations is the possibility of side effects. The point of vaccination is to induce an immune response, and vaccines are specifically designed to do this. Some individuals mount more of an immune response than necessary. This could result in a mild vaccine reaction, such as lethargy or running a slight fever the day of the vaccine, or it could cause a serious life-threatening allergic reaction. These reactions may be difficult to predict, so it is important that you alert your veterinarian to any reactions your dog may have had to vaccines in the past. Vaccinating your dog only against those diseases that it is likely to be exposed to will limit the chances that it will have an adverse reaction.
Keep in mind that no vaccine is 100 percent effective against the disease it is supposed to prevent and that no vaccine is 100 percent safe. However, many of the vaccines are considered safe, effective, and much less risky than the diseases themselves. The chance that your dog will have a reaction to a vaccine and the severity of that reaction is usually much less than the danger of not being adequately vaccinated and becoming infected with the disease. It is important to balance out the risks versus the benefits in determining vaccination schedules for your pets.
Nancy Dreschel, DVM, Ph.D - Pennsylvania State University
For more information
2006 Canine Vaccine Guidelines, Revised http://www.aahanet.org/PublicDocuments/VaccineGuidelines06Revised.pdf
Vaccinations – AVMA animal health brochure http://www.avma.org/animal_health/brochures/vaccination/vaccination_brochure.pdf