How do cat vaccinations work and which ones are important for your beloved feline friend? Here's a rundown of key cat vaccinations your veterinarian is likely to suggest.

When you fall in love with a cat, you want to do everything you can to help him stay happy and healthy. Including keeping him current on vaccinations. Cat vaccinations are a common component of feline preventative care, and according to the American Veterinary Medical Association (AVMA), they have prevented death and disease in millions of kitties. 

How do they do that? Trent Eddy, DVM, of Ironhorse Veterinary Care in Leawood, Kansas, describes vaccines as substances that stimulate the body's immune system to fight particular disease-causing organisms, such as viruses or bacteria. 

"The vaccine will cause the recipient to produce antibodies against the organism we're trying to target so that if that cat is ever exposed, its body will already know how to fight and prevent that disease," he explains. "The vaccine itself is made up of the disease-causing organism we're trying to attack, though it's a dead or weakened version so the recipient doesn't get sick."

While vaccines can cause allergic reactions in cats, the occurrence is rare and the AVMA encourages cat owners to weigh the risks against the benefits of protecting your pets (and even your family) from serious and sometimes fatal diseases. 

According to the American Association of Feline Practitioners (AAFP) and the American Animal Hospital Association (AAHA), the vaccines your cat needs will depend on its health, age, and lifestyle, as well as the diseases that are common where you live. Your veterinarian will work with you to determine which vaccines to give your cat and when. Generally, feline vaccines are divided into two categories: core and noncore. 

Core Cat Vaccinations

Core vaccines are typically recommended for all felines—indoor cats and outdoor cats—Eddy says. Here's a breakdown of which vaccines are considered core and what they guard your cat against:

Rabies Vaccine

Rabies is a zoonotic disease, meaning it can be passed to humans. It's most often transmitted by the bite of an infected animal. The AVMA notes that the disease is almost always fatal once outward signs appear (for example, aggressive behavior, seizures, excessive drooling), as there are no treatment options at this point. 

Feline Viral Rhinotracheitis Vaccine

Marked by severe upper respiratory disease, feline viral rhinotracheitis is caused by feline herpesvirus 1. Signs include nose and eye irritation and discharge, and some cats can develop pneumonia and mouth ulcers. 

Feline Calicivirus Vaccine

There are several strains of feline calicivirus, but it typically causes upper respiratory disease and mouth ulcers. It's associated with gingivitis (inflammation of the gums) and stomatitis (inflammation of the mouth and lips). 

Feline Panleukopenia Vaccine

Also called feline distemper or feline parvo, feline panleukopenia is caused by the highly contagious feline parvovirus, which attacks the cat's bone marrow, lymph nodes, and intestinal lining. Infected cats release the virus into the environment via their urine, poop, and nasal secretions, where it can survive as long as a year.  

According to Eddy, the vaccines for feline viral rhinotracheitis, feline calicivirus, and feline panleukopenia are often delivered together in a combination three-in-one vaccine called the FVRCP vaccine. 

Feline Leukemia Vaccine

For cats under a year old (kittens) and any cat with an unknown vaccine and health history, the feline leukemia vaccine (FeLV) is considered a core vaccine as of the 2020 guidelines issued by the AAHA and AAFP. FeLV affects up to 3% of all cats in the U.S. and is spread as a viral infection when a cat comes into contact with infected fluids, like saliva. Cats can pass it to one another through grooming, sharing the same water bowl, and fighting. In cats, the virus can cause severe and even terminal illness.

Even before the updated 2020 guidelines, Eddy treated this vaccine as core for all kittens—even if the owner planned to strictly keep the cat indoors. "Everybody thinks they're going to have an indoor cat when they get a kitten, but six months later, they might change their mind and start letting their cat go outside," he explains. "And because I probably won't see that cat until its annual wellness visit, it will be at risk of exposure for months before I learn about the change."

The AAFP lists the FeLV vaccine as noncore when a cat is older than a year and has a known vaccine and health history.

Noncore Cat Vaccinations

Noncore vaccines aren't necessarily recommended for all cats. Whether or not a cat receives a noncore vaccine depends on its exposure risk (for example, whether it goes outside or spends time with other cats), as well as the kitty's age, health, and history. AAFP lists the following as noncore feline vaccines:

Chlamydophila Felis

A bacterial pathogen, chlamydophila felis is primarily spread through direct cat-to-cat contact. It mainly causes eye inflammation, but it's also associated with upper respiratory problems. 

Bordetella Bronchiseptica

Another bacterial pathogen, bordetella bronchiseptica can cause serious upper respiratory problems. 

Feline Immunodeficiency Virus

Transmitted from cat to cat through saliva—most often via bite—feline immunodeficiency virus can weaken the infected kitty's immune system, leaving it vulnerable to other infections. It can also cause cancer. 

Cat Vaccination Schedule 

The proper time to vaccinate your cat will depend on such variables as its age, health, and the vaccine in question. Core vaccines may require regular booster shots, as well, and the frequency varies by product. 

Visit with your veterinarian to determine the proper vaccine schedule for your cat—especially if he's been recently adopted. Because kittens' immune systems aren't fully developed, they are most at risk for developing an infectious disease. However, newly adopted adult cats will also need to get on a vaccine schedule. Be sure to let your veterinarian know if your cat's lifestyle suddenly changes—maybe your indoor cat starts going outdoors or you start fostering a cat from a shelter—as this could change his recommended care.

How to Prepare Your Cat for the Vet

AAFP notes that cats are most comfortable with what they know, so don't wait until the day of the vaccine appointment to introduce your cat to the carrier. Fluffy may need days or even weeks to get used to it. Talk to your veterinarian about how you can transform the carrier into your cat's home away from home. To this end, AAFP recommends leaving the carrier where your cat regularly hangs out and placing familiar bedding, as well as treats, catnip, or toys, inside to encourage Butterscotch to enter on his own. Remember: Cats learn best with positive reinforcement, not punishment.

Despite your best efforts, your cat may still have anxiety and stress when visiting the veterinarian. Eddy recommends pre-visit medication for these fur babies to help them relax, which can make the situation better for you, your cat, and the veterinary team. Talk with your veterinarian if you think this might be a good option for your pet. 

What to Expect After Cat Vaccinations

Eddy says general lethargy the day of the vaccination and the day after is the most common side effect he sees. Some soreness at the site of the injection, much like people feel after getting a flu shot, is also possible. "It depends on the individual's immune response to the vaccine," he explains. "Lethargy is typically a positive sign because it means the body is really being stimulated to make antibodies against the disease-causing organism."

While lethargy and soreness aren't a cause of concern, vaccine reactions are. "They can happen with any cat, any age, and any vaccine," Eddy says. "They're rare, but they can happen. In fifteen years, I've only seen a handful." 

These reactions can include vomiting, diarrhea, facial swelling, and breathing problems. Eddy notes that these reactions typically appear almost immediately, while the cat is still at the clinic. If your cat starts showing these signs within hours of being vaccinated, it needs immediate veterinary care. Before scheduling your appointment, be sure to let your veterinarian know if your cat has ever had a reaction to a vaccine or medication. 

Though rare, another serious potential vaccine reaction is the development of a tumor at the injection site. Called injection-site sarcomas, these tumors can form weeks, months, and even years after the vaccine was given. Let your veterinarian know if you notice any lumps under the skin where your cat has had a vaccine.