How Vaccines Are Given
Most vaccines are given by injection through a sterile needle either under the skin (subcutaneously) or into the muscle (intramuscularly). Some vaccines can be administered in drop or mist form, into the nostrils or eyes. The most novel way to give vaccines is transdermally, which involves applying them topically to the skin. Some vaccines are given in combination; these are called “multivalent” vaccines. Multivalent vaccines have antigens for several diseases combined in a single injection. In the past, many combination vaccines contained 5 or more different antigens. The current trend is to reduce the number of antigens in multivalent vaccines, supposedly to increase effectiveness and decrease the burden on the vaccinated animal’s immune system.
Why Vaccines May Not Provide Complete Protection
While vaccines are usually extremely effective in preventing infectious diseases, no vaccine is 100% effective all of the time. There are a number of reasons why vaccines might fail, including:
- Improper handling and storage
- Improper administration
- Errors in calculating the appropriate dosage
- Failure to boost the vaccine properly
- Poor health; run-down cat; stressed cat
- Immune system overload from too many or too frequent vaccines
- Infection prior to vaccination
- Heavy parasite load
- Presence of immunosuppressive drugs (steroids, chemotherapeutical agents, others) in the animal
- Passive immunity from maternal antibodies
Nonetheless, most animals do develop resistance to the diseases that they are fully and appropriately vaccinated against.
Are Vaccines Safe?
Most vaccines are considered by medical experts to be safe and extremely beneficial. However, they can cause adverse reactions in some pets. The most common adverse vaccine reactions in cats are tiredness, running a low-grade fever and loss of appetite (“going off feed”). Some cats develop a small, non-painful lump at the site where the vaccine was injected, which usually disappears within a month. In rare cases, a cat will develop facial swelling or have a severe allergic reaction to a vaccine called “anaphylaxis,” which typically is accompanied by vomiting, diarrhea, difficulty breathing (dyspnea) and less commonly, collapse. Intense facial itchiness may also occur. Anaphylactic reactions usually are not fatal, as long as the cat is taken to a veterinarian and treated immediately.
There is a documented association between some vaccines – especially feline leukemia virus and rabies vaccines - and development of sarcomas in cats. Sarcoma is a form of cancer of connective and soft tissues. If a bump at the injection site lasts longer than a month, the cat should be examined by a veterinarian.
Are There Viable Alternatives to Vaccination?
There are no viable alternatives to vaccinating your companion animal against common or dangerous diseases. Despite the occasional adverse vaccine reactions, it is almost universally accepted in the medical community that vaccination plays an extremely important role in protecting pets – and people - from infectious disease. Some owners resist having their animals vaccinated. The standard veterinary protocols for vaccinations – including which vaccines to give and when to give them - are constantly evolving, based on the current state of scientific knowledge. Blood samples can be taken to evaluate the levels of circulating antibodies that may provide protection against specific diseases. Although titer levels do not always provide evidence of actual immunity, high titer levels indicate that the animal probably has a reduced risk of becoming infected by the particular organism, and that it probably is safe to administer vaccines against that organism at a longer than usual interval. At this time, not all laboratories are standardized to allow accurate interpretation of titer results, nor can immunity to all diseases be tested this way. Some states require vaccination against certain diseases, especially rabies, as a matter of community health.