As a cat owner, chances are you’ve heard about feline leukemia (FeLV) and naturally, had concerns. You may find some relief to know that it’s possible to help protect your cat from feline leukemia through vaccination.
No vaccine is 100% effective, but by vaccinating, the chances of developing FeLV are greatly reduced. There are many benefits to having your cat vaccinated against this dangerous condition, which we'll discuss.
In the article below, we’ll answer many common questions about feline leukemia, like:
What feline leukemia virus is
The common signs and symptoms of feLV
Feline leukemia treatment options
What the feline leukemia vaccine can do for your cat
We’ll also explore some of the most important reasons for protecting your pet from this disease, too. If your cat develops concerning symptoms, it’s important to visit your nearest emergency vet hospital. VEG ER for Pets is open 24/7 to see your cat.
What is feline leukemia?
Feline leukemia virus (FeLV) is one of the most common and serious viral diseases affecting cats worldwide. Despite its name, it isn't a type of cancer. Instead, it's a contagious virus that attacks a cat's immune system and bone marrow, making it much harder for the body to fight off infections and increasing the risk of certain cancers, blood disorders, and other life-threatening illnesses.
After exposure, not every cat develops lifelong infection. Some cats are able to eliminate the virus with the help of their immune system, while others develop a persistent infection that can lead to serious health complications over time. Because feline leukemia virus weakens the immune system, even minor infections can become severe — making early detection and prevention especially important.
How do cats get feline leukemia?
Cats become infected with feline leukemia virus through close, prolonged contact with an infected cat. Because the virus is fragile and survives only a short time outside the body, it is typically spread through everyday interactions between cats rather than through the environment.
Cats are most commonly exposed through:
Mutual grooming
Sharing food and water bowls
Bite wounds from fighting
An infected mother passing the virus to her kittens before birth or while nursing
Some cats are more susceptible to feline leukemia
Although any cat can become infected, some are at much greater risk than others.
Cats most susceptible to feline leukemia virus include:
Kittens, whose immune systems are not yet fully developed
Outdoor cats
Cats that fight with other cats
Cats living in shelters or crowded multi-cat environments
Cats living with an FeLV-positive cat
Unvaccinated cats with outdoor access
Young kittens are especially vulnerable to develop a lifelong infection after exposure than adult cats.
Signs and symptoms of feline leukemia
The way feline leukemia symptoms develop can vary from cat to cat. Some cats never become seriously ill, while others develop a progressive infection that slowly weakens the immune system over months or years.
As immune function declines, cats become increasingly vulnerable to bacterial, viral, and fungal infections, anemia, inflammatory diseases, and certain cancers. This is why it's important to recognize the first warning signs of this disease.
Know the first signs of feline leukemia
One of the challenges of diagnosing feline leukemia is that many infected cats appear perfectly healthy at first. Some may have no symptoms for months — or even years — after becoming infected.
As the virus begins affecting the immune system, the earliest feline leukemia symptoms may include:
Because these signs are common to many illnesses, it's important to have your cat evaluated by a general practice veterinarian, especially if they spend time outdoors or live with other cats.
Common feline leukemia symptoms
Persistent lethargy
Loss of appetite
Progressive weight loss
Pale gums caused by anemia
Enlarged lymph nodes
Chronic diarrhea
Frequent respiratory infections
Eye infections
Skin infections
Poor coat condition
Mouth ulcers or severe gum disease
Reproductive problems
Lymphoma or other cancers
Because these symptoms overlap with many other medical conditions, laboratory testing is needed to confirm whether feline leukemia virus is responsible.
Is feline leukemia contagious?
Yes. Feline leukemia is one of the most contagious viral diseases affecting cats, but it generally requires close, repeated contact with an infected cat to spread.
Unlike some viruses, FeLV does not survive long outside the body, so simply touching contaminated surfaces is unlikely to spread infection.
If you are introducing a new cat into your household, it's a good idea to have them tested and vaccinated for FeLV before allowing close contact with your resident cats.
Can dogs get feline leukemia?
No. Your pup is safe from the disease. Feline leukemia virus is species-specific, meaning dogs, people, and other household pets cannot become infected.
How feline leukemia is tested and diagnosed
Veterinarians typically diagnose feline leukemia using a simple blood test called an ELISA test, which detects viral proteins in the bloodstream. If a cat tests positive, additional testing may be recommended to determine whether the infection is temporary or persistent.
Depending on your cat's condition, your veterinarian may recommend:
An Immunofluorescent Antibody (IFA) test
PCR testing in certain cases
Complete blood work
Urinalysis
Imaging studies if cancer or other complications are suspected
Testing is commonly recommended for:
Newly adopted cats
Sick cats
Cats exposed to FeLV-positive cats
Cats before entering multi-cat households
Cats prior to vaccination if their FeLV status is unknown
What is the feline leukemia vaccine and how does it work?
The feline leukemia vaccine helps prepare your cat's immune system to recognize and respond quickly if it encounters the virus. While no vaccine provides complete protection, vaccination significantly reduces the risk of developing a persistent FeLV infection in cats that may be exposed.
The vaccine is considered a lifestyle vaccine, meaning your veterinarian will recommend it based on your cat's individual risk factors. It is commonly recommended for:
Kittens
Outdoor cats
Cats with outdoor access
Cats living with FeLV-positive cats
Cats in multi-cat households where exposure risk exists
The vaccine is typically given as an initial series followed by booster vaccinations based on your veterinarian's recommendations and your cat's lifestyle. Even vaccinated cats benefit from routine veterinary care and limiting unnecessary exposure to infected cats whenever possible.
Why prevention of feline leukemia is so important
Listed below are reasons why it is important to help prevent your cat from feline leukemia:
6 reasons why you should vaccinate your cat for feline leukemia
The feline leukemia vaccine works
First and foremost, the feline leukemia vaccine works well to prevent feline leukemia virus infection in cats and protect cats from this dangerous condition. Although there is always a slight risk of a cat developing feline leukemia even after vaccination, this risk is low and is very uncommon for most pet cats. Generally, this negative result is seen in cats who are strays.
Otherwise, this injection is an excellent way to provide some protection for your feline friend. Your vet can give you more specific information about how the vaccine works and what to expect from it with regard to your cat and its success.
The feline leukemia vaccine is safe
For most cats, there are no significant side effects from getting the feline leukemia vaccine. Most cats experience nothing more than a little bit of pain at the injection site for a day or two, although some cats may run a low fever following any type of injection. These very minor side effects are nothing to worry about. Less commonly, allergic reactions can occur but are usually mild and can be easily treated by your veterinarian. Symptoms of an allergic reaction can include vomiting, diarrhea, labored breathing, wheezing, hives, facial swelling, weakness, or collapse.
With any vaccine in cats, the most severe complication is vaccine-associated sarcoma. This is a tumor that can develop many years later at a previous injection site from any medication, although vaccination sites are most common. This occurs in less than 1 in 1,000 cats who are vaccinated during their lifetime.
If your vet believes your cat has any reason to avoid getting the feline leukemia injection, you will be told beforehand. Keep in mind, however, that in the majority of cats, this injection is safe, effective, and relatively painless to receive as well.
Feline leukemia can be deadly
While a small percentage of cats will fight off the feline leukemia virus or suppress it, the sad news is that all cats who develop signs of it will not survive, or pass away from complications related to it. This infection suppresses the cat's immune system and leaves them vulnerable to infections or cancer.
There is no cure for feline leukemia, and management options only include keeping your cat comfortable and protecting her from secondary infections. A diagnosis of feline leukemia typically means that the cat will die within three years.
This is by far the most compelling reason to have your cat vaccinated against this deadly disease. You can protect your cat from contracting this illness and help her live a longer, healthier, happier life by simply getting her the vaccination against it.
Feline leukemia can be painful
Unfortunately, feline leukemia can be painful and unpleasant for your cat to experience. It is not a quickly deadly disease, but one that your cat may suffer with for several years before it finally wins out. It can be upsetting and difficult to watch your cat go through this type of suffering.
To prevent your cat from having to deal with such a painful and challenging experience, you can have her vaccinated against feline leukemia. Although it is always possible that she could become sick with another condition, you'll be able to protect her from one of the most severe.
Feline leukemia is Contagious to other Cats
Feline leukemia virus is extremely contagious to other cats. By vaccinating your cat against this condition, you can prevent her from potentially spreading it to any other cats she may come into contact with.
Even if you keep your cat indoors all the time, it's important to have her vaccinated. There is always a risk that she could escape the home and become exposed to the virus. Vaccinating at-risk cats (and all cats!) helps reduce the spread of this serious disease.
Feline leukemia vaccines are required by some locations
If you plan to travel with your cat and stay in a hotel, or if you plan to board your cat at any point throughout her life, she may need to have her feline leukemia vaccination before going to these places.
More and more destinations and boarding facilities alike are requiring feline leukemia vaccinations for cats. If you have any travel plans involving your cat, keeping her up to date on her shots can help make the process smoother.
Can a cat survive feline leukemia? Life expectancy of cats with FeLV
It’s important to understand that almost all cats exposed to feline leukemia will not survive. Some cats remain healthy for months or even years after diagnosis, while others develop serious illness much sooner. In extremely rare cases, a cat may be able to fight the virus.
The outlook depends on how the virus affects the individual cat. Some cats successfully suppress the virus and experience few long-term effects, while others develop a progressive infection that weakens the immune system over time.
Cats with persistent feline leukemia virus infection often have a shorter lifespan because they are more vulnerable to infections, anemia, and cancer. Although cats with progressive FeLV live an average of two to three years after diagnosis, cats staged with a regressive infection can live a full life, with attentive veterinary care, regular monitoring, and prompt treatment of secondary illnesses.
Life expectancy depends on the stage of the infection.
Stages of feline leukemia
Regressive infection
If a cat’s immune system fights the FeLV infection, they may enjoy normal longevity while the virus is in an inactive state in the bone marrow. Living in this stage, the cat is not contagious to other cats. However if the virus reactivates and they do develop clinical signs (becoming a progressive infection), the prognosis becomes terminal.
Progressive infection
The majority of cats diagnosed with feline leukemia are staged as progressive infection. This means they have active virus within the bloodstream. At this stage, life expectancy is 2-3 years, and the cat’s infection can spread to other cats.
Is feline leukemia treated by a vet?
Unfortunately, there is currently no cure for feline leukemia virus. Instead, feline leukemia treatment focuses on controlling complications, supporting the immune system, and maintaining the best possible quality of life.
Depending on your cat's condition, treatment may include:
Antibiotics for bacterial infections
Intravenous fluids to treat dehydration
Nutritional support
Pain management
Blood transfusions for severe anemia
Chemotherapy for certain cancers, including lymphoma
Medications to stimulate appetite or control nausea
Regular physical examinations and bloodwork to monitor disease progression
Your general practice veterinarian may also recommend keeping your cat indoors, feeding a complete and balanced diet, maintaining parasite prevention, minimizing stress, and seeking veterinary care promptly if any new signs of illness develop.
How to prevent feline leukemia
Preventing feline leukemia is far easier than treating its complications.
In addition to vaccination, cat owners can reduce the risk of infection by:
Keeping cats indoors whenever possible
Testing newly adopted cats before introducing them to resident cats
Separating FeLV-positive cats from FeLV-negative cats when appropriate
Scheduling routine veterinary wellness exams
Discussing your cat's lifestyle and vaccination needs with your veterinarian
Combining vaccination with responsible household management offers the best protection against feline leukemia virus.
VEG is open 24/7 to care for your cat's emergency symptoms
If you suspect your cat has feline leukemia or your cat is showing signs of the disease, contact us by calling your nearest VEG emergency animal hospital location. If your cat is experiencing concerning symptoms, walk in anytime; no appointment needed. Our emergency vets are available every day, including weekends and holidays, to provide the best care for your cat.
