Veterinarian with a vaccine in their hand holding a cat

Key takeaway

Feline leukemia is caused by a virus that targets cats' immune systems and is one of the top causes of mortality in cats. Feline leukemia is spread by saliva and urine, and cats can become ill if they are bitten by an infected cat, share the same food bowl or litter box, or encounter with the body fluids of an infected cat. Although feline leukemia is incurable, vaccination can help prevent it. Continue reading to discover more about feline leukemia.

The feline leukemia virus, commonly referred to as FeLV, is one of the leading causes of death in cats. It is a virus that infects the cat, causing leukemia, a cancer of the white blood cells. This common disease can spread from cat to cat, and once infected, cannot be permanently cured. However, many cats still manage to live their lives while infected, as the disease often takes years to run its full course.

The only way to know for sure whether your cat’s symptoms are caused by FeLV is to have them diagnosed by a veterinarian. However, it’s a good idea to know the signs of feline leukemia and to know when you should consider taking your cat to the vet.

Read on to find out more about the feline leukemia virus, feline leukemia symptoms, and feline leukemia treatment.

What Is Feline Leukemia Virus (FeLV)?

The feline leukemia virus weakens the immune system by harming the cat’s white blood cells. This makes cats more susceptible to other diseases and illnesses, such as cancers and blood disorders, like leukemia—cancer of the blood. The condition progresses and is typically fatal1.

The virus is capable of infecting both domestic and wild cats. Over the last 30 years, widespread testing and immunization initiatives have helped to lower the disease's prevalence, and around 3% of cats in the United States were afflicted in 20102. Outdoor cats, unneutered males, and cats with other ailments are at a higher risk of contracting the disease. Luckily, this illness is only dangerous to other cats. Other pets and humans in the household are safe from the virus.

Cats most at risk of FeLV infection are those that have been in close contact with infected cats, either through sustained frequent proximity or through bite wounds. Cats living with sick cats or cats with uncertain infection status, cats left outside unattended where they might be bitten by an infected cat, and kittens delivered to infected moms are examples of cats at a higher risk of infection1.

How Common Is Feline Leukemia?

It’s relatively common, affecting 2-3% of cats in the U.S., and is the leading viral killer of cats2. The risk of exposure to feline leukemia goes up when cats live in large colonies, share food bowls with other cats, or come directly into contact with infected cats often. The prevalence of feline leukemia can also vary depending on the geographic region, climate, and other factors.

Feline leukemia is one of the leading causes of death in cats, affecting 2-3% of cats in the United States.

How Do Cats Get Feline Leukemia?

Cats transmit the feline leukemia virus through contaminated saliva and urine. Direct contact with these body fluids, reciprocal grooming, shared litter boxes and food dishes, and fighting can all expose uninfected cats to the infection. In order for cats to become ill, they need to be exposed to the virus on a regular basis. Mother cats can infect their kittens while they are still in the womb or through breast milk. Transfer from a mother to her kittens is most likely the most prevalent source of disease. The virus is particularly dangerous to young kittens, although adults may have some natural immunity. Cats of all ages can contract the virus and develop the disease1.

If your cat was living in a shelter with many other cats, came from a home where there were many other cats, or was birthed by a feral mother, it’s a good idea to have them checked and tested by a veterinarian. With the right support, it’s possible for your cat to live a good life for a prolonged period.

What Are the Symptoms of Feline Leukemia?

Veterinarian smiling down while holding a cat

Whether your cat’s eyes are watering or they haven’t eaten in days, feline leukemia can present in a number of different ways, especially given that cats infected with the virus become more susceptible to other diseases, cancers, and infections. Some of the most common signs to watch out for (and consult a vet about) include:

  • Lethargy
  • Decreased appetite and weight loss
  • Seizures and other neurological episodes
  • Vision problems
  • Gum inflammation
  • Sickly coat appearance
  • Abscesses and swellings
  • Jaundice (yellowing of the skin)
  • Chronic skin conditions and itching
  • Respiratory problems and infections
  • Noticeable behavioral changes
  • Fever
  • Diarrhea, vomiting, and other gastrointestinal difficulties
  • Enlarged lymph nodes
  • Reproductive issues3

Many of the symptoms listed here can come from numerous different causes, and shouldn’t be considered causes for alarm on their own. If you notice one or more of these symptoms in your cat, especially if they persist over multiple days, it’s critical that you get your pet seen by a veterinarian. Only a professional will be able to conduct the tests necessary to determine the causes of your cat’s symptoms, and rule out feline leukemia virus.

How Is Feline Leukemia Diagnosed?

The only way that you can discover for sure that your cat is struggling with feline leukemia is by having them seen by a veterinarian. When you take your cat to the vet, they will likely conduct a physical examination along with a series of diagnostic tests. They can use the tests to rule out other causes of your cat’s symptoms, such as a cold or flu, or some other allergy or infection.

They will also likely use one of three common tests that specifically seek out the FeLV virus3:

  • ELISA (enzyme-linked immunosorbent assay) test that looks for antigens responding to the FeLV in the cat’s blood
  • IFA (indirect fluorescent antibody) test is used to determine whether the virus has infected the cat’s white blood cells, a sign of more advanced cases
  • PCR (polymerase chain reaction) tests are used to determine if the cat’s bone marrow has become infected with the virus, another sign of more advanced cases of the disease

The latter two tests are usually only used if the ELISA test comes back positive, as they are used to estimate how advanced the disease is. The more advanced the FeLV has progressed, the more likely it is that the disease will become fatal sooner3.

While a feline leukemia diagnosis is emotionally difficult to hear, it’s important to remember that it’s not an automatic death sentence. Under the right conditions and with the right supportive care, it’s possible for an infected cat to live a normal life for years after they have received their first diagnosis.

Is Feline Leukemia Treatable?

There is no cure for feline leukemia, but with proper veterinarian care, a balanced diet, and other factors, some cats can survive for years without issues. Typically, cats survive around 2.4 years after being diagnosed. However, with the right care, they may live longer1.

The average life expectancy of a cat diagnosed with feline leukemia is 2.4 years.

In most cases, treatment will consist of treating the problems that feline leukemia causes. Because FeLV weakens cats’ immune systems, cats that are infected with the virus are more likely to suffer from other infections, like bacterial infections or the flu1. Treatment is directed towards managing the symptoms of these secondary illnesses, as there is no direct cure or proven treatment for FeLV itself.

It’s also important to note that there is a feline leukemia vaccine, which can be used to prevent the feline leukemia virus to some degree. It is not 100% effective, but if your cat lives under high-risk circumstances, the virus may be able to decrease the chances that your cat becomes infected, even if exposed. This vaccine is not usually included in the common round of vaccines most cats get at shelters or the vet, so be sure to discuss whether this option is smart for your cat with your veterinarian.

How to Protect Your Cat From Feline Leukemia

Because there is no proven cure or direct treatment for feline leukemia, the best way to keep your cat safe from the disease is to prevent them from being exposed in the first place. There are a few steps that you can take3, :

You can prevent feline leukemia by keeping cats indoors, reducing exposure from potentially infected cats, getting the feline leukemia virus vaccine, feeding your cat a well-balanced diet, and providing your cat with routine veterinary checkups.

  • Keep cats indoors
  • Reduce exposure from potentially infected cats
  • Get the feline leukemia virus vaccine (if you and your vet determine that this is wise or necessary)
  • Feed your cat a well-balanced diet that promotes immune system health
  • Provide your cat with routine veterinary checkups to screen for any potential health problems

Final Notes

Feline leukemia can be a difficult disease to face, but with the right supportive care, your cat can remain relatively healthy for some time. The right preventative measures can help your cat stay safe from exposure to the virus in the first place.

For other chronic conditions, like cat allergies and anxiety (which have symptoms that may often be mistaken for feline leukemia symptoms), Dutch has solutions. Our telemedicine for pets service is built to connect users with the medications they need to keep pets happy and healthy, all at an affordable subscription price. Sign up and schedule a checkup today to find out how a Dutch-affiliated vet can help improve your cat’s quality of life.

References

  1. Levy, Julie K., & Burling, Amanda. “Feline Leukemia Virus (FeLV).” Merck Veterinary Manual, 29 Nov. 2021, https://www.merckvetmanual.com/cat-owners/disorders-affecting-multiple-body-systems-of-cats/feline-leukemia-virus-felv 

  2. “Feline Leukemia Virus.” Cornell University College of Veterinary Medicine, 29 Nov. 2019, https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/feline-leukemia-virus

  3. “Common Cat Diseases.” American Society for the Prevention of Cruelty to Animals, 29 Nov. 2021, https://www.aspca.org/pet-care/cat-care/common-cat-diseases

  4. “Feline Leukemia (FeLV).” American Humane, 29 Nov. 2021, https://www.americanhumane.org/fact-sheet/feline-leukemia-felv/