Late to the Party. Getting Your Cat Vaccinated As An Adult


Vaccinating cats is extremely important to protect them from dangerous and potentially fatal diseases. While many people understand the need to properly vaccinate kittens, it’s also crucial not to skip or delay vaccines for adult cats. Vaccines help prevent infectious diseases caused by viruses and bacteria that can lead to severe illness, permanent disabilities, and even death in cats if contracted. Vaccinating on time provides maximum immunity against these threats. Vaccines help protect against specific infectious diseases caused by viruses and bacteria. The use of vaccines has prevented death and disease in cats for decades. Even indoor cats can be exposed to viruses and bacteria from people, other pets, boarding facilities, groomers, and more. While kitten vaccinations provide early protection, timely adult cat vaccines are vital boosters that continue immunity throughout their lives.

Core Kitten Vaccines

Kittens require a series of core vaccines as their immune system matures. The key core vaccines for kittens include:

FVRCP – This combination vaccine protects against three viral diseases: feline viral rhinotracheitis (FVR), calicivirus (C), and panleukopenia (P). FVR is an upper respiratory infection caused by feline herpesvirus type 1 (FHV-1). It can lead to severe symptoms like sneezing, coughing, eye and nose discharge. Calicivirus causes oral ulcers and upper respiratory infection. Panleukopenia is a highly contagious and potentially fatal disease caused by the feline parvovirus (FPV) that attacks the gastrointestinal tract and immune system 1.

Rabies – Rabies is a fatal viral infection that affects the central nervous system. The rabies vaccine is considered a core vaccine because the disease is zoonotic, meaning it can spread from cats to humans 1.

FeLV – Feline leukemia virus (FeLV) suppresses the cat’s immune system and can lead to cancer and other secondary diseases. Kittens are routinely vaccinated against FeLV until one year of age since the virus is highly contagious 2.

Core Adult Cat Vaccines

Adult cats (over 1 year old) also require core vaccines to protect against common and deadly feline diseases. According to the 2020 AAHA/AAFP Feline Vaccination Guidelines, the core vaccines for adult cats include:

  • Rabies – Rabies vaccines are required by law. The initial dose is typically given at 12-16 weeks, with a booster 1 year later. After that, rabies vaccines are boostered every 1-3 years depending on local laws and vaccine type.
  • FVRCP – This 3-in-1 vaccine protects against feline viral rhinotracheitis, calicivirus, and panleukopenia (distemper). After the kitten series, FVRCP boosters are recommended every 3 years lifelong.

Booster shots for adult cats are important because immunity can wane over time. FVRCP and rabies antibodies gradually decrease after vaccination. Giving boosters according to guidelines ensures your cat maintains protective immunity. Skipping boosters puts your cat at risk if exposed to these dangerous viruses. Discuss your cat’s lifestyle and risk factors with your veterinarian to determine the optimal booster schedule.

Non-Core Vaccines

Non-core vaccines are those that are more situation-specific and given based on the cat’s risk factors and lifestyle. According to the AAHA guidelines, the most common non-core vaccines for cats include:

  • Feline leukemia virus (FeLV) – For cats with outdoor access or exposure to other cats where FeLV status is unknown
  • Chlamydia felis – For cats entering a shelter, boarding facility, or multi-cat household
  • Bordetella bronchiseptica – For cats at risk of exposure or showing respiratory signs
  • Feline infectious peritonitis (FIP) – Controversial vaccine not routinely recommended

These vaccines may be recommended by your veterinarian based on your cat’s lifestyle and risk factors. For example, the FeLV vaccine is important for outdoor cats who could get exposed by fighting with infected cats. Chlamydia and bordetella vaccines would help cats entering shelters or boarding facilities where these contagious bacteria spread easily. Your vet will determine if any non-core vaccines are necessary for your cat.

It’s Never Too Late

Many pet owners may feel guilty or worried if they’ve missed some of the recommended kitten vaccines for their cat. However, the good news is that it’s never too late to vaccinate an adult cat. Even if a cat missed certain vaccines as a kitten, they can still benefit greatly from receiving those vaccines as an adult. According to The Healthy Pet Club, “It’s never too late to start a vaccination programme. If you have an older cat, it is not too late to start a vaccination programme and your vet will be able to advise a schedule to get them protected.”

When an adult cat receives a vaccine they missed as a kitten, their immune system will still develop immunity against that disease. It simply takes the immune system a bit longer to develop full immunity when the vaccine is given at an older age. But adult cats absolutely can develop strong protection when receiving late vaccines. So even if you discover your adult cat is behind on their shots, don’t hesitate to get them vaccinated. Consult with your vet to determine the best vaccination schedule for your cat’s needs.

While immunity takes longer to develop in adult cats, vaccinating them is still crucial to protect them against dangerous and potentially fatal diseases. It’s always better late than never when it comes to cat vaccines. Don’t let guilt or worry stop you from getting your adult cat the vaccines they need to live a healthy life.

Risk Factors

Certain lifestyle factors can increase a cat’s risk of exposure to infectious diseases, making vaccination even more critical [1]. Cats with outdoor access are at higher risk since they have increased exposure to other cats and wildlife that may be carrying diseases [2]. Multi-cat households are another risk factor, as infectious diseases can spread rapidly between cats in close contact [3]. Shelter cats are also at elevated risk since shelters have high cat population density and frequent introductions of new cats [1]. Additional factors like stress, poor nutrition, and underlying illness can further suppress the immune system, leaving cats vulnerable to infections [2]. Because of these risk factors, veterinarians strongly recommend following the standard vaccine schedules for cats with outdoor access, in multi-cat homes, or adopted from shelters. Vaccination provides critical protection by priming their immune systems to mount an immediate response if exposed to a virulent virus or bacteria.



Vaccine Schedule

The American Animal Hospital Association (AAHA) provides the following guidelines for core kitten vaccinations in their 2020 AAHA/AAFP Feline Vaccination Guidelines:

  • Feline herpesvirus-1 (FHV-1): Every 3-4 weeks from 6-8 weeks of age until 16-20 weeks of age.
  • Feline calicivirus (FCV): Every 3-4 weeks from 6-8 weeks of age until 16-20 weeks of age.
  • Feline panleukopenia virus (FPV): Every 3-4 weeks from 6-8 weeks of age until 16-20 weeks of age.
  • Rabies virus: First dose no earlier than 12 weeks of age, with a booster 1 year later.

For adult cats, the AAHA recommends core vaccines every 3 years, including:

  • FHV-1
  • FCV
  • FPV
  • Rabies virus

Seniors cats (over 7 years old) may need only every 3 year boosters for rabies and panleukopenia viruses according to a reduced vaccine protocol. More frequent FHV-1 and FCV boosters may be warranted in shelters, cats with frequent exposure to other cats, or with certain medical conditions.

For indoor only cats leading low risk lifestyles, some veterinarians may recommend skipping the FHV-1/FCV boosters after the initial kitten series. However, rabies and FPV boosters are still recommended every 3 years.

Side Effects

Most cats tolerate vaccines well with minimal side effects. The most common side effects are mild and temporary, lasting only a day or two. These can include:

  • Soreness, tenderness or swelling at the injection site
  • Lethargy
  • Decreased appetite
  • Slight fever

According to PetMD, these reactions are normal and show that your cat’s immune system is responding properly to the vaccine [1]. Severe reactions like facial swelling, vomiting, diarrhea or trouble breathing are very rare.

If side effects last more than a day or two or seem to get worse, contact your veterinarian. With prompt care, most cats recover fully.

Lifestyle Considerations

There are some key differences between recommended vaccine schedules for indoor versus outdoor cats. Indoor cats have a much lower risk of being exposed to dangerous infectious diseases, while outdoor cats face higher threats of contagion (Dunnellon Animal Hospital, 2021). As such, tailored vaccine plans are often created based on the cat’s lifestyle and degree of outdoor access.

One of the most critical vaccines for all cats, regardless of indoor/outdoor status, is the rabies vaccine. Rabies is a fatal viral disease that can spread between species. All cats should receive the rabies vaccine on the schedule recommended by a veterinarian, usually starting around 12-16 weeks old with a booster 1 year later. Local jurisdictions may also require rabies vaccination by law (PetMD, 2019). This protects both the cat’s health and public safety.

For indoor cats, core vaccines like rabies, feline viral rhinotracheitis, calicivirus, and panleukopenia are recommended at kittenhood, with boosters every 3 years. Outdoor cats need those plus additional vaccines like feline leukemia and Chlamydia on an annual schedule due to higher risk. Consult a vet on the optimal plan (Montecito Pet Hospital, 2021).

While indoor cats have a lower risk of infectious disease, owners should still discuss an appropriate vaccine schedule with their veterinarian. Even occasional outdoor access like an enclosed patio may warrant extra immunizations. Overall, lifestyle is a key factor in tailoring the ideal cat vaccination plan.


In conclusion, it’s never too late to vaccinate adult cats according to the recommendations of your veterinarian. While kittens require an initial vaccine series, adult cats also need continuing vaccine boosters throughout their lives. Core vaccines like rabies, FHV-1, FCV, and FPV should be administered regularly based on lifestyle risk factors. Non-core vaccines may also be recommended, especially for outdoor cats. Some vaccines even provide better immunity when given to adult cats versus kittens. So adult cat vaccination is extremely important for ongoing disease prevention. Be sure to discuss your cat’s vaccine needs with your veterinarian, and follow their recommended schedule. There are many great resources online to learn more about the latest feline vaccination guidelines from AAHA and AAFP.

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