How Vaccines Are Administered
Most vaccines are given by injection through a sterile needle, either under the skin (subcutaneously) or into the muscle (intramuscularly). Some vaccines are administered in drop or mist form into the nostrils or eyes. The most novel way to give vaccines is to put them directly onto the skin. Vaccines given together in one shot are called combination or multivalent vaccines. Combination vaccines protect against more than one disease. The current trend is to reduce the number of diseases vaccinated against at the same time.
Vaccines are extremely effective in reducing the risk of infectious disease. However, no vaccine is 100% effective all of the time. Lots of things can cause vaccines to fail:
- Improper handling and storage
- Improper administration
- Disinfectants on the injection site
- Dosage errors
- Failure to boost regularly
- Poor health; stress; weak or compromised immune system
- Immune system overload (too many vaccines; too frequent vaccination)
- Disease incubating at time of vaccination
- Heavy parasite load
- Hormonal fluctuations
-Presence of immunosuppressive drugs in the animal (corticosteroids, chemotherapy drugs, others)
- Maternal antibody interference
- Old age
Fortunately, vaccine failure is the exception rather than the rule.
Vaccines are considered safe and extremely beneficial. They occasionally cause mild reactions, such as lethargy, low-grade fever and appetite loss. Some dogs develop a small lump at the vaccination site, which usually disappears within a few weeks. Very rarely, dogs may have an allergic reaction to a vaccine, called “anaphylaxis,” which is accompanied by vomiting, diarrhea, difficulty breathing and, even less commonly, collapse. Itchiness and facial swelling can also occur. Anaphylactic reactions can be severe but usually are not fatal, as long as the dog is treated immediately. Some vaccines are associated with the development of sarcomas in cats; this is extremely rare in dogs. If a bump at an injection site lasts longer than a few weeks, the pooch probably should be seen by a veterinarian.
There aren’t any viable alternatives to vaccines. Despite the occasional odd reaction, it is almost universally accepted that vaccines are necessary to protect pets, and people, from infectious diseases. Many states require owners to vaccinate their dogs (and cats) against certain infectious diseases, especially rabies. Veterinary protocols about which vaccines to give and when to give them are always evolving with the state of scientific and medical knowledge. Increasingly, blood samples are being evaluated to determine the levels of circulating antibodies against certain diseases. This is called “checking titer levels.” While high titer levels don’t always mean that the dog is immune to the particular disease, they do indicate that it has a reduced chance of becoming infected and may support prolonging the interval between vaccinations. Not all laboratories can check titer levels or accurately interpret titer results.