Vaccination is the process of exposing a dog's immune system to specific heat-killed germs, live germs rendered incapable of causing disease, or toxins, and germ products. Once the immune system encounters these disease-causing agents, it manufactures antibodies against them. Antibodies are protein substances that neutralize the effects of an antigen, a disease-causing foreign substance in the body.

Today's dogs are fortunate to have vaccinations against a number of killer diseases, including parvovirus and distemper. Before the development of vaccines for dogs, many died every year because their immune systems weren't strong enough to fight off the diseases.

Vaccination Frequency

While vaccinations have been a boon to dogs, too much of a good thing can be just as bad as not having it at all. Veterinarians are currently rethinking the requirement that dogs be vaccinated every year. Over-vaccination has been associated with autoimmune hemolytic anemia in dogs, a disease that can be fatal.

Many schools of veterinary medicine now recommend a standard three-shot series for puppies to protect against parvovirus, adenovirus 2, parainfluenza, and distemper. The first vaccination is given at six to eight weeks of age, the next three to four weeks later, followed by the final shot in another three to four weeks. A rabies shot is given after sixteen weeks of age. After the initial three-shot series, they recommend that dogs receive booster shots for these diseases at one year of age and every three years after that. Note that some states require annual rabies vaccination instead of triennial (every three years) vaccination.

Types of Vaccinations

Three types of vaccinations are used in dogs: killed virus, modified live virus (MLV), and recombinant. Killed vaccines cannot cause disease and are stable during storage, but they are often associated with vaccine reactions and require more frequent booster shots. Modified live vaccines are stronger and provide longer-lasting protection against disease. In a dog with a weakened immune system, however, they have the potential to cause disease.

Recombinant vaccines are a new development. They're made by splicing gene-sized fragments of DNA from a virus or bacteria, and they work by delivering specific antigen material to the dog on a cellular level. This cuts out the risk of vaccination reactions that sometimes occur when vaccinating with the entire disease-causing organism.

Recombinant vaccines cannot cause disease. It's not known yet how long the immunity they provide lasts, but there's a good chance they will soon replace MLV and killed-virus vaccines. Recombinant vaccines are available for distemper, rabies, and Lyme disease. The future may also bring more nasal vaccines, which may be less likely to cause adverse reactions.

Vaccine Reactions

It's not uncommon for pugs to have reactions to vaccinations. Their lips and eyes may swell, or they can develop hives. In rare cases, the dog can go into potentially fatal anaphylactic shock. Most reactions occur within twenty minutes after the injection, but it's a good idea to schedule your pug's vaccinations for early in the day and monitor the dog for hives or other problems. Ask your veterinarian to spread out individual vaccinations instead of giving a five-in-one combination shot, and avoid scheduling a rabies vaccination at the same time as other vaccinations. If you know your pug reacts to vaccines, you can ask your veterinarian to provide allergy medication before giving the injection.

Which Vaccines Are Really Necessary?

Core vaccines — those for distemper, adenovirus 2, parvovirus, and rabies — are essential for all dogs. These viral diseases are serious (and can be fatal), common, highly contagious among dogs, or are a threat to humans (rabies). Distemper, adenovirus 2, and parvovirus can be treated only with supportive therapy such as intravenous fluids. There's no medication that can cure the diseases, although antibiotics can help ward off secondary bacterial infections. Rabies is fatal once signs develop.

Other vaccines can be given based on the amount of risk the dog faces. Vaccines for coronavirus, Lyme disease, parainfluenza, leptospirosis, bordetella, and giardia fall into this “noncore” category. The risk of infectious disease varies throughout the country. Your veterinarian can help you tailor a vaccination program that's appropriate for your pug, based on his current health and the incidence of infectious disease in your area.