Vaccinating your adult cat or kitten can be one of the most important steps you take to prevent disease in your pet. Two veterinary associations, the American Association of Feline Practitioners (AAFP) and the Academy of Feline Medicine (AFM) Advisory Panel on Feline Vaccines, have developed recommendations for the selection and administration of vaccines for cats. Feline vaccinations fall into two basic categories, the "core" vaccines, or those that are recommended for most cats, and the ancillary vaccines, or those that are only recommended for a small percentage of cats. Although most feline veterinarians are familiar with both groups of vaccines and how and when they should be administered, it is also important for cat owners to educate themselves on what is available and the benefits and risks of vaccinating their pets. The following provides a synopsis of the current vaccines available and when and to which cats they should be administered.

Feline panleukopenia: Feline panleukopenia (also known as feline distemper) is caused by the feline parvovirus. This virus can remain contagious in cages, litter boxes, and bowls for months to years. Cats are infected with this virus after ingesting the virus orally, usually from where another cat has defecated. Remember, viruses are microscopic and because they can be in the environment long after the cat that shed them is gone, the only way to protect against them is to vaccinate. Recently, studies have shown that canine parvovirus can also be contagious to cats, but can be protected against with the current feline vaccines. The vaccines available for protection against feline panleukopenia are excellent and offer almost total immunity to the virus. Although an intranasal vaccine is available, the injectable vaccine is more effective. Younger cats are more susceptible to infection from this virus, and clinical signs include fever, loss of appetite, vomiting, diarrhea, weakness, and even death. Vaccination is highly recommended for all cats at 12 weeks of age followed by a booster in 2-4 weeks (3-4 weeks is ideal), then again in one year, then no more frequently then every three years.

Feline viral rhinotracheitis and feline calicivirus: Most infectious upper respiratory disease in cats is caused by either feline herpesvirus (the cause of viral rhinotracheitis) or by the calicivirus. These viruses are transmitted from cat to cat through nose-to-nose contact or by fomites (objects such as water or food bowls). Although most cats recover from the infection on their own, similar to humans with the common cold, there are some cats that can develop a chronic form of the disease. These cats can have periods where they appear healthy, but during times of stress will develop the sneezing and runny nose and eyes associated with this virus. Persistently infected cats will also shed the virus for months to year, and therefore can act as a source of infection for other cats. Vaccines against these viruses come in intranasal, conjunctival (applied to the eye), and injectable forms. Unlike the panleukopenia vaccine, the rhinotracheitis and calicivirus vaccines only induce relative, not complete, protection. Therefore, even vaccinated cats may get a mild respiratory infection. It is recommended that all cats be vaccinated against these viruses, usually at 12 weeks of age with the injectable form. A booster should be given in 2-4 weeks (3-4 weeks is ideal) then again in one year, then every three years. Very young kittens that may be born into a contagious environment (catteries, boarding facilities, or shelters) can be vaccinated at younger than 12 weeks with the conjunctival vaccine. However, these vaccines produce more side effects than the injectable form and should be used with caution.

Rabies: Rabies is mainly transmitted through the bite wounds of infected mammals. Although rare in rodents such as mice and voles, there can be large populations of infected bats and skunks and other animals depending on the geographic location. Although cats are relatively resistant to rabies, they can be potential source of infection for humans and there is no treatment available. According to the AAFP Advisory Panel "rabies virus vaccination is highly recommended for all cats, and is required by law in some states and municipalities; products approved for use every year or every 3 years are available. Statutes governing the administration of rabies virus vaccines vary considerably throughout the United States; veterinarians should comply with the legal requirements of their area." Vaccination for indoor cats is also recommended due to the potential for exposure from a bat or other animal that has entered the house.

Feline Leukemia virus infection: The feline leukemia virus can infect cats by saliva or nasal discharge, biting, or sharing food and water dishes. Unlike other viruses, the feline leukemia virus can also be transmitted from a mother cat to her kittens while they are still in the uterus or in the milk while they are nursing. This virus attacks the immune system and clinical signs are most often anemia, secondary respiratory infections, weight loss, lethargy, anorexia, cancer, and even death. Kittens under 16 weeks of age and cats living in households or catteries with infected cats are the most susceptible to this virus. Vaccination against feline leukemia is recommended for cats at risk of exposure (those who go outdoors or are living with an infected or potentially infective cat). Because not all vaccines produce total protection against the virus in all cats, the best way to prevent infection is to prevent exposure to infected cats. Most veterinarians recommend testing for the virus (a quick 10 minute procedure requiring a small amount of blood) to identify any infected cats. Cats should be tested for feline leukemia infection before initial vaccination and can be tested as early as 6 weeks. There are some potentially serious side effects from the leukemia vaccine that need to be taken into consideration when deciding to vaccinate a cat. Adverse effects from vaccination can include local swelling or pain, transient lethargy or fever, post-vaccination granuloma formation (a gathering of inflammatory cells that cause a benign lump), and most seriously, vaccine associated sarcomas. A sarcoma is a type of a mass that is comprised of cancerous cells. Sarcomas can spread from the site of the injection down into surrounding connective tissue, muscle, and bone. Even with chemotherapy, radiation, and surgical removal some cats have died from vaccine-associated sarcomas. Although sarcomas have been reported from vaccines other than the feline leukemia virus (rabies is thought to be associated with possible sarcoma formation), current scientific research links sarcoma formation most often with feline leukemia vaccination. It is important to realize that incidents of sarcomas are very rare, and seem to be from vaccines that were mostly administered in previous years before the use of the current, more refined vaccines. For most cats, the risk contacting the virus is far greater than the risk of a vaccine reaction. It is recommended that cats receive the first vaccination at 8-12 weeks, a booster in 2-4 weeks (3-4 weeks is ideal), and a booster once a year thereafter.

The next group of vaccines is considered ancillary. For some cats, they may be beneficial and therefore recommended, but for most cats they fall outside the usual vaccination protocol.

Chlamydiosis: Chlamydia psittaci is a bacteria that can infect the eye membranes and respiratory tract of cats. Treatment with an appropriate antibiotic is usually curative. Cats that are vaccinated are not protected from infection, but will get less severe clinical signs. The vaccine itself can cause lethargy, depression, anorexia, and fever, and is there fore only recommended for cats that are in environments where infections associated with clinical disease have been confirmed.

Feline infectious peritonitis: Feline infectious peritonitis, or FIP, is a disease caused by the feline coronavirus. Crowded, multiple cat environments have the highest rate of infections where the virus is passed from the feces of one cat to the mouth of another. Affected cats rarely survive even in the face of aggressive treatment. Many studies have been conducted on the vaccine currently available for FIP. At this time, the vaccine is not recommended due to the lack of evidence that the vaccine induces protection from the virus.

Dermatophytosis: Dermatophytosis, or ringworm, is caused by a fungal infection. Although eliminating the infection from individual cats can be accomplished by shaving, using medicated shampoos, and oral antifungals, treating multiple cats can be expensive and difficult. Although a vaccine is available, it has not been proven to prevent infection or eliminate the fungus from infected cats, and is therefore not recommended.

Bordatella bronchiseptica: This bacteria can infect the respiratory tract of many animals and can cause fever, discharge from the eyes or nose, sneezing, and coughing. Although most cats are exposed to this bacteria during their lives, cats in shelters and multiple cat households are most often infected. The clinical signs are most often resolved by the cats own immune system. The vaccine available is not recommended due to the lack of studies on its ability to protect against infection or limit the severity of the disease. Some shelter and catteries have been using the vaccine, but its effectiveness has not been evaluated.

Giardia: Giardia is a protozoan parasite that attacks the intestinal tract, causing a range of clinical signs from none to watery diarrhea. Cats are usually infected form contaminated water or from the feces of infected cats. Although the vaccine available is not commonly recommended due to the lack of data supporting its effectiveness, it would be reasonable to consider its use to lessen the severity of diarrhea. The best method to eliminate giardia infections is to treat infected cats with proper medication, limit access to infected water and to practice proper hygiene and sanitation. Feline immunodeficiency virus: A new vaccine, known as Fel-O-Vax® FIV, was just approved by the USDA for use against the feline immunodeficiency virus (FIV). This virus, commonly referred to as "feline AIDS," causes the immune system to weaken. Affected cats can have many disorders, including oral infections, eye disease, cancer, and bone marrow disease. Most feline veterinarians recommend that all cats be tested for FIV before they are introduced to a household due to the viruss high degree of contagiousness. There is no cure available against the disease and many affected cats die within 3 years of infection. Although Fort Dodge Animal Health, the manufacturers of the vaccine, is very enthusiastic about its effectiveness, at this time the vaccine has not been recommended for use. According to the AAFP advisory board, "The absence of tests that distinguish cats vaccinated with Fel-O-Vax FIV from infected cats, coupled with questions regarding the vaccines ability to induce protection against all the subtypes and strains of FIV to which cats night be exposed, makes the decision to recommend use of this product far from straightforward."

It is important that all cat owners develop a good working relationship with a veterinarian with whom they trust to discuss their cats vaccination schedule. Most kittens should have an initial examination at the age of 6 to 8 weeks to asses general health. Feline practitioners generally do not start the vaccination series until the kitten is at least 10-12 weeks of age, but a FeLV/FIV screening test can be performed at the initial visit.

It is recommended that a veterinarian perform all vaccinations. Vaccines by different manufacturers can vary considerably by their components and their effectiveness and only a veterinarian can direct you to the vaccine that will work best for your cat. Vaccines must be kept in a strict and precise state of refrigeration for them to by effective, an important aspect that is often overlooked by feed and pet stores selling "over-the counter" vaccines. More importantly, the site of administration, whether nasal, oral, intramuscular, or subcutaneous, can be best determined by a veterinarian who is aware of the current recommendations. The site in which the vaccine is given may potentially affect the chances of a vaccine reaction. At this time the AAFP recommends that only single dose vaccines vials be used. This helps ensure that the pet will receive the adequate amount of antigen and decreases the risk of contamination. The AAFP panel also "discourages the use of polyvalent (multiple component) vaccines other than those containing combinations of feline panleukopenia virus, feline herpesvirus, and feline calicivirus, exclusivelyas the number of antigens in a vaccine increases, so too does the probability of associated adverse events."

Vaccine reactions can occur and range in severity. Mild general lethargy and injection site soreness are not uncommon. Immediate vaccine induced allergic reactions can also occur. With these types of reactions the animal can have vomiting, diarrhea, facial swelling, and other signs of shock and must be treated immediately by a veterinarian. Although vaccine reactions are frightening to the owner, other than the vaccine-induced sarcomas, they are rarely serious or life threatening. In almost all instances, the benefit of vaccination far outweighs the risk of any vaccine reaction.

Related articles:
AAFP / AFM Feline Vaccination Recommendations: Quick Guide
Vaccination Associated Sarcomas