The One Vaccine Cats Don’t Need


There are several important vaccines available for cats that can protect them from dangerous diseases. Veterinarians categorize these vaccines into “core” vaccines that are vital for nearly all cats, and “non-core” vaccines that may be recommended depending on the cat’s lifestyle and risk factors. The core vaccines for cats include feline viral rhinotracheitis, calicivirus, panleukopenia, and rabies. Non-core vaccines that may be recommended include feline leukemia virus, chlamydia, and feline infectious peritonitis. This overview will provide information on each of these key feline vaccines and guidelines on their necessity.

Feline Viral Rhinotracheitis

Feline viral rhinotracheitis is caused by feline herpesvirus type 1 (FHV-1), which infects the upper respiratory tract of cats [1]. It is one of the most common and contagious upper respiratory infections in cats. The virus is spread through direct contact with infected respiratory secretions, saliva, and eye discharges from other cats. Symptoms include sneezing, coughing, congestion, runny nose and eyes, fever, and sometimes mouth or eye ulcers. Kittens are especially vulnerable and the infection can be life-threatening. The FVRCP vaccine provides effective protection against this highly contagious viral infection by stimulating the production of antibodies. Annual booster vaccinations are recommended to maintain immunity. The FVRCP vaccine is considered a core vaccine for all kittens and cats by veterinarians [2].


Calicivirus or feline viral rhinotracheitis (FVR) is a viral upper respiratory infection that is very contagious among cats and caused by a calicivirus [1]. It causes inflammation of the upper airways, including nasal discharge, sneezing, ulcers on the tongue, mouth, and respiratory tract. In severe cases, pneumonia can develop. Kittens under 16 weeks old who contract calicivirus tend to develop more severe symptoms than adult cats. While there is no cure for calicivirus, supportive care from a veterinarian can help alleviate symptoms. Vaccination is critical to prevent infection, starting with a series of vaccines for kittens [2].


Panleukopenia, also known as feline distemper, is caused by the feline parvovirus which infects and destroys white blood cells, leaving cats vulnerable to secondary infections.[1] The virus is highly contagious and spreads easily between cats through bodily secretions. Panleukopenia can lead to severe gastroenteritis characterized by vomiting, diarrhea, anorexia, and dehydration. The disease has a high mortality rate if left untreated, especially in unvaccinated kittens.

All kittens should receive a series of panleukopenia vaccines, with the final dose given at 16-20 weeks old. Adult cats need a panleukopenia booster vaccine every 1-3 years depending on risk factors and veterinary recommendations. The panleukopenia component is included in combination vaccines like FVRCP. Vaccination helps prevent infection and decrease disease severity.

Despite vaccination, panleukopenia outbreaks can still occur in dense cat populations. Apart from vaccination, prevention includes isolating infected cats, disinfecting environments, and limiting exposure of susceptible kittens. While panleukopenia can be devastating, proper prevention and vaccination according to veterinary protocols significantly reduces risk.



The rabies vaccine is required by law for cats in most areas of the United States and Canada, according to the Westchester Veterinary Medical Center. Cats are susceptible to rabies infection from the bite of wildlife such as bats, raccoons, skunks, and foxes. The rabies virus is almost always fatal once clinical signs develop, so vaccination is crucial for preventing rabies in cats.

The vaccine schedule varies based on the type of vaccine used, but the initial vaccine is typically given at 12-16 weeks of age. The American Association of Feline Practitioners recommends revaccinating one year after the initial dose, and then vaccinating every three years thereafter using a three year, non-adjuvanted vaccine. Local laws may have different revaccination requirements. Most rabies vaccines for cats are considered to be extremely safe, with minimal side effects like mild soreness at the injection site.

Feline Leukemia

Feline leukemia is caused by the feline leukemia virus (FeLV), a retrovirus that suppresses the cat’s immune system and increases susceptibility to other diseases and cancers 1. The FeLV vaccine helps provide immunity by exposing the cat to antigens without causing disease. It is considered a core vaccine for kittens, but a non-core vaccine for adult cats 2.

The FeLV vaccination is highly recommended for outdoor cats or cats in shelters/multi-cat households where exposure risk is higher. It prevents shedding and progressive infection in exposed cats. Side effects are typically mild but can include lethargy and transient fever 3. The initial vaccine series is two doses 2-4 weeks apart, and then annual boosters are recommended.


Chlamydia in cats is caused by the bacterium Chlamydophila felis. This bacteria infects the conjunctiva and respiratory tract of cats and can cause conjunctivitis, rhinitis, and pneumonia [1]. Chlamydia is spread between cats through direct contact and shared litter boxes or food bowls. Symptoms include ocular and nasal discharge, sneezing, fever, and lethargy. Chlamydia can also spread to humans, causing a respiratory infection.

The vaccine for chlamydia is considered non-core for cats. It is only recommended for cats at high risk of exposure, like those living with multiple other cats. Side effects are mild but can include lethargy and reduced appetite for a day or two after vaccination. Immunity develops 3-4 weeks after the initial dose and lasts about one year [2]. Annual boosters are recommended for high risk cats.

Feline Infectious Peritonitis

Feline infectious peritonitis (FIP) is caused by a feline coronavirus (FCoV) (Zoetis). While there is a vaccine available for FIP, it is not routinely recommended by veterinary experts and guidelines. The American Animal Hospital Association (AAHA) Feline Vaccine Guidelines state that “The Task Force lists the feline infectious peritonitis (FIP) vaccine as not generally recommended. This vaccine is labeled for administration from 16 weeks…” (AAHA).

There are a few key reasons why FIP vaccines are not recommended (Cat Vets):

  • The vaccine does not provide complete protection against FIP
  • The vaccine interferes with serologic tests that detect coronavirus antibody titers
  • The vaccine may sometimes trigger the development of FIP in cats

While some veterinarians may recommend the FIP vaccine in high-risk situations, routine vaccination is not advised due to lack of sufficient evidence of effectiveness and potential risks (Cat Vets).


In summary, there are several core and non-core vaccines recommended for cats. The core vaccines that are recommended for all cats include feline panleukopenia virus (FPV), feline viral rhinotracheitis (FHV-1), feline calicivirus (FCV), and rabies. These vaccines help protect cats against serious and potentially fatal diseases. According to the American Animal Hospital Association, the feline leukemia virus (FeLV) vaccine is also recommended for cats under 1 year old.

The non-core vaccines that may be recommended depending on the cat’s risk factors and lifestyle include feline immunodeficiency virus (FIV), Chlamydia felis, and Bordetella bronchiseptica. These are considered optional vaccines that are given based on a veterinarian’s recommendation. In summary, while the core vaccines are essential for all cats, the non-core vaccines can provide additional protection when warranted.


American Veterinary Medical Association. “Vaccination Recommendations.” AVMA, 2022,

Centers for Disease Control and Prevention. “Diseases & Conditions – Pets and Animals.” CDC, 2022,

Webster, C. Pet Health Guide for Cats & Dogs. Publisher, 2022.

Veterinary Partner. “Vaccines Recommended for Cats.” VetPartner, 2022,

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