Vaccine administration
The vaccine administration site should be relatively clean to minimize the introduction of bacteria during vaccination. Always follow current vaccination site recommendations as outlined in the 2006 American Animal Hospital Association (AAHA) Canine Vaccine Guidelines and the 2006 American Association of Feline Practitioners (AAFP) Feline Vaccination Guidelines. To safely administer vaccinations, proper and appropriate restraint of the patient is necessary. For example, if someone accidentally receives a needle stick when a bovine brucellosis vaccine is being administered, medical attention is required since the brucellosis vaccine is live and the disease is considered zoonotic.

It is especially important to administer a vaccine by its intended route. Significant disease can be caused when vaccines are incorrectly administered. An intranasal canine Bordetella bronchiseptica vaccine given subcutaneously can result in local inflammatory reactions, abscess formation, liver failure, and death. The modified-live subcutaneous feline FVRCP is a temperature-sensitive vaccine that relies on administration at core body temperature. When administered oronasally, significant upper respiratory infection can result. This most commonly happens when vaccine is spilled on the cat's fur, and the cat licks up the spilled vaccine. Spilled vaccine can be cleaned off the fur with alcohol; use dilute bleach for spills in the environment. If a vaccine is administered incorrectly, it is advisable to contact the manufacturer and begin supportive treatment, if warranted.

Patient safety
When developing vaccination protocols for your geographic area, keep in mind that the veterinarian will need to evaluate patient needs on an individual basis. There is not a one-size-fits-all vaccine protocol. An apartment-dwelling dog does not face the same risk factors as a working field trail dog. To clarify usage, vaccines have been broken up into two groups called core and noncore. Core vaccines, some of which are required by law, protect against diseases that have public health significance, are highly infectious, and pose risk of severe disease. These vaccines are considered high-benefit and low-risk to the patient population. Administration of noncore vaccines should be based on the risk associated with vaccine administration vs. the individual's risk of contracting the disease. The core vaccines recommended in the 2006 AAHA Canine Vaccine Guidelines and the 2006 AAFP Feline Vaccination Guidelines are:

Dogs
• rabies (killed vaccine; administered according to local legal statutes)
• canine parvovirus (CPV or CPV-2), canine adenovirus-2 (CAV-2)
• canine distemper (CDV; modified live or recombinant vaccine)]

Cats
• rabies (killed or recombinant vaccine; administered according to local legal statutes)
• panleukopenia virus (FPV)/feline herpesvirus-1
• feline calicivirus (FHV-1/FCV)

Individual situations may necessitate an altered vaccination protocol. Recent exposure to disease, illness, convalescent illness, fever, local reaction from prior vaccine, medical therapy, age, pregnancy, and whelping are all valid reasons to modify or postpone a planned vaccination. The administration of some modified-live virus vaccines can infect young puppies and kittens (less than 4 to 5 weeks of age), causing development of the disease and death. Vaccinating pregnant females with modified-live virus vaccines can lead to birth defects or abortions. The immune system of any compromised pet will be unable to mount an appropriate immune response to the administered vaccine.

Adverse reactions
Possible adverse events of vaccination include mild reactions such as local inflammation, swelling, pain, irritation, hair loss, abscess formation, or simply a failure to immunize. More severe reactions include anaphylaxis, immunosuppression, autoimmune disorders, transient infections, the development of long-term carrier states, and local development of tumors. After vaccination, patients commonly experience mild fever, decreased appetite, or lethargy lasting one or two days. Rare vaccine-related outcomes include hypertrophic osteodystrophy and juvenile cellulitis associated with the modified-live virus distemper vaccine in Weimaraners and vaccine-associated sarcomas in cats (see "Vaccine-related sarcomas").

Anaphylaxis is a rare, life-threatening, immediate allergic reaction to something ingested or injected that can result in shock, respiratory and cardiac failure, coma, and death. An anaphylactic reaction to a vaccine usually occurs within minutes to hours of the vaccination. It may be characterized by the sudden onset of diarrhea, vomiting, seizures, facial swelling, hives, and signs of shock such as pale mucous membranes, prolonged capillary refill time, tachycardia, and hypotension. Treatment of anaphylaxis may include administration of an antihistamine, corticosteroid, and epinephrine; IV fluid therapy; and continued monitoring and observation.

If a pet has any type of vaccine reaction, make sure to record this in the medical record so that certain vaccines are no longer administered in the future or preventive measures can be taken. The American Veterinary Medical Association (AVMA) encourages the reporting of any adverse events to the vaccine manufacturer and the U.S. Department of Agriculture's Center for Veterinary Biologics (CVB). This will aid in the monitoring and recognition of trends in the adverse effects of vaccination.