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Feline Leukemia Virus

Angela is a cat and dog lover who has made special efforts to learn as much as she can about the animals she cares for.

This article contains all you need to know about the Feline Leukemia Virus (FeLV).

This article contains all you need to know about the Feline Leukemia Virus (FeLV).

What Is the Feline Leukemia Virus?

The Feline Leukemia Virus, or FeLV, is a retrovirus found in cats. A retrovirus changes the genetic makeup of infected cells by reversing some of the genetic code, making their bodies more susceptible to infection and eventually leading to death.

FeLV is transferred through bodily secretions such as urine, milk, feces, and saliva. Cats often transfer the disease by mutual grooming, nursing, or bite wounds. It can also be transmitted through sharing a litter box or a feeding dish, although this transmittal type is much less frequent.

Two to three percent of all cats have the virus, and their life expectancy cannot be predicted. Like AIDS, there are two stages of feline leukemia: Primary and secondary viremia. Primary viremia is more similar to HIV in that their life is not yet at risk but will be if the disease progresses. A cat can stay in this stage for many years. Secondary viremia is when the bone marrow or other tissues are severely affected. Once secondary viremia begins, the disease will eventually take the cat's life.

Mucus Membranes of a Cat With the Virus

Notice how the cat's mucous membrane is very pale and white in color, rather than the healthy pink color that is typical of a cat.

Notice how the cat's mucous membrane is very pale and white in color, rather than the healthy pink color that is typical of a cat.

Good for Cats with FeLV

Symptoms of FeLV

The first sign of FeLV is no sign at all. A cat may appear to be very healthy for months or even years before they begin showing signs of the disease. Because they do not have immediate symptoms, they often have had a chance to infect many other cats by the time they are diagnosed. Once the disease has progressed, here are the most common symptoms:

  • Loss of Appetite: If the cat chooses not to eat at all, they may end up with fatty liver disease, which will eventually cause yellowing of their skin. If not treated, they will die of this disease rather than leukemia.
  • Dull Coat: Due to their body's inability to produce healthy natural oils, they may become very greasy due to a lack of desire to clean themselves.
  • Weight Loss: This is often slow—unless they have stopped eating.
  • Pale Gums: An example of this can be seen in the photo above.
  • Infections: They can develop in the eye, urinary tract, skin, and upper respiratory system.
  • Lethargic Behavior: If you know the odd behaviors of cats, you may be wondering how you can determine lethargy in a feline. Although if you notice your cat has become increasingly lethargic, or a kitten, which should be curious and active, you may want to have your pet checked out.
  • Anemia is the number one reason young cats die of FeLV.
  • Stunted Growth in a Kitten: If you have a kitten in a litter that doesn't seem to be growing, most likely it has feline leukemia. Unless treated, its life expectancy will be very short.
  • Seizures: These are often due to neurological damage.
  • Persistent Fever
  • Persistent diarrhea
  • Tumors
  • Miscarriages

Healthy Kitten

Kittens are much more susceptible to the virus.

Kittens are much more susceptible to the virus.

FeLV in Kittens

Due to their size and age, kittens are more susceptible to feline leukemia than adult cats. Adult cats become infected 30 percent of the time when exposed to the disease, whereas a kitten becomes infected 100 percent of them by the same amount of illness. Therefore, even if your kitten was born to a healthy mother, it is crucial to protect them from becoming infected by keeping them indoors and away from known infected felines until they are fully grown.

Physical and Habitual Signs in Kittens

Kittens who contract FeLV have a higher chance of early death due to their already compromised immune system. The most significant indicator that your kitten might be infected is if they seem lazier and not curious. They may also seem smaller and grow at a slower rate than an average feline of the same age.

Also, kittens with the disease tend not to want to eat, which is very dangerous because cats have ineffective livers. Often just a few days of going without food will severely affect their health. Any time your kitten or cat chooses not to eat, even for a day or two, you should take them immediately to the veterinarian. It is a sign that something bigger could be wrong, but unchecked, it can also result in liver failure and death.

There is no cure for FeLV, but you can make your cat more comfortable as the disease progresses.

There is no cure for FeLV, but you can make your cat more comfortable as the disease progresses.

Treatment Options

There is no cure for FeLV, but there are things you can do to help your cat live longer:

  • Spay or neuter your cat to prevent the further spreading of the disease. Also, pregnancy can adversely affect a cat that has FeLV. Not only is the chance of survival of the kittens low, but the pregnancy might become too much for the sick cat's body to handle. If they get pregnant and the kittens survive, the kittens' chance of having the disease is very high.
  • Feed them a nutritious and balanced diet by providing them with cat food high in protein. Avoid uncooked foods because they will not be able to fight against food-borne illnesses that often result from raw foods.
  • Bring your pet to the veterinarian every six months, so the doctor can check for any infections that you may overlook. Also, notify the vet as soon as you see any changes in behavior or health.
  • Keep your pet indoors, which protects other cats and protects your cat from getting any infections or diseases from other animals. Your pet will be very susceptible to even minor illnesses or infections. A minor infection that may cause diarrhea in a healthy cat may take an infected cat's life.
The FeLV vaccination is a two part series that is given to kittens at eight weeks old, and again three weeks later.

The FeLV vaccination is a two part series that is given to kittens at eight weeks old, and again three weeks later.

The Vaccine

The FeLV vaccine is a two-part vaccine. The first portion is best given to a kitten between eight and ten weeks; the second is between eleven and thirteen weeks. Although, unlike many vaccines, it is not one hundred percent effective. The effectiveness is somewhere between 90–95 percent.

The vaccine can be given in two different ways. One is with a needle, another using VET JET, which is delivered with a burst of air by placing it in contact with the skin. Most vet offices use a needle since not all offices have a VET JET.

A Very Small Risk

There is a minimal risk of causing tumors, so the vaccine is usually given in the left-back leg. They do this because it makes the location site easy to monitor if a tumor develops. Even if a tumor does grow, a cat can survive without the left-back hind leg. However, this risk is very slight. There is also an even smaller risk that the cat could develop the disease itself. Most vets do agree the benefits outweigh the cost, although you want to talk to your vet about your particular cat.

Marley Family Fund: Help Support Cats With FeLV



This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

Questions & Answers

Question: How long will a cat live after they stop eating anything?

Answer: A cat can survive for about two weeks without eating. If a cat is not eating or drinking, though, they could only survive three days. Unfortunately, cats have very poor livers, and if they go for even a short amount of time without food, they can develop fatty liver disease. This is very hard to cure, and often leads to death.

© 2012 Angela Michelle Schultz


Angela Michelle Schultz (author) from United States on September 12, 2019:

I am so sorry Marsha. We have been there, it is so hard when a loved one is sick.

Marsha on September 08, 2019:

My cat is week eats a little his skin is yellow the vet said he has jaundice he looks really sick I cry every night she gave him meds to get him to eat and some pink stuff it begins with a b but so scared I'm going to wake up and his gone he also has felve I just hope the meds will work is there anything else I can do for him I love my baby so much it breaks my heart seeing him go through this

Steve on December 05, 2018:

I have a two year old cat named Larry I found him abandoned he has feline leukemia so sweet friendly and full of personality, he is very healthy but I dread the day this illness takes him from me I have other cats so I have to keep him in his own room so he can’t infect any of my other cats , I hope some day they find a cure

Angela Michelle Schultz (author) from United States on August 17, 2012:

I'll have to look into that. Thank you for bringing this to my attention.

bdrum11 on August 17, 2012:

I echo the other comments thanking you for writing this informative article. It's heart-wrenching to hear the stories of this terrible disease taking its toll. One update you might consider to the article that could serve as another helpful resource to readers is that, while it's true there is no cure for FeLV, there is a product called Lymphocyte T-Cell Immunomodulator (LTCI) that received USDA approval in 2006 as a treatment aid for this indication. At least there's now an option to check out!

Dianna Mendez on August 11, 2012:

My cat died of this virus a few years back. It was heart wrenching to watch him slowly pass away. He was so sweet and never indicated to us that he was in pain. Thanks for posting this and I hope it helps others.

Angela Michelle Schultz (author) from United States on August 09, 2012:

Love the cats name!

Denise Handlon from North Carolina on August 08, 2012:

Angela, I'm glad you posted this very informative hub. I just found out about this virus when I took our two kittens for a wellness checkup. I had not heard of this before because I've not had a housecat for a pet in many years. Our two kittens came to us by way of a mama stray who revealed to us her litter one day. We have no idea if there were other kittens, and I assume there were more than two, but we suspiciously look at the neighborhood toms and play the "who's your daddy" game.

In the meantime, our vet educated us and tested the little ones. TC Tiger (TomCat Tiger), and Raisin Le Pew (aka stinkbomb) came out with a clean bill of health and will be attending their second checkup in a couple of weeks for their follow up booster and neutering appointment. No babies allowed in my house-at least not the four pawed, furry version! LOL

Great hub; rated up and I/U BTW-love the avatar and it was the Peacock which caught my eye in the first place! Beautiful.

Angela Michelle Schultz (author) from United States on August 06, 2012:


I think this one is so heart wrenching because they can be healthy for so long with the disease, and then the slightest infection can kill them.

Angela Michelle Schultz (author) from United States on August 06, 2012:

Jackie, I had a cat that was affected by insulation as well. For whatever reason she loved the stuff, and would eat it. She actually is still living, but for awhile was very unhealthy. Fortunately, once we realized what the problem was, it fixed itself.

Angela Michelle Schultz (author) from United States on August 06, 2012:

Lucky Cats, I actually am not the person who set up Marley's fund, but when I saw it, I wanted to add it onto my site, to make others aware that a fund is out there.

Lela from Somewhere near the heart of Texas on August 06, 2012:

I've lost two great cats to FLV. They lived fairly normally until they were about 8 years old. Then they suddenly got sick and died quickly. It was not a nice disease. But then, there probably isn't a nice disease at all.

It hurts to lose a pet, no matter what the cause.

Jackie Lynnley from the beautiful south on August 06, 2012:

What a shame. My cat is seventeen and she has been through a lot but I think it was mostly from getting into insulation somewhere years back. Sort of an allergy thing but we seem to have it whipped for the most part. She is white, which I have read makes her weaker for some reason but she seems to be enjoying age and just soaking up the sun.

Interesting write, voted up.

David Hunt from Cedar Rapids, Iowa on August 06, 2012:

This is an awesome hub. Thank you for writing such a clear and easy-to-read article. Our cats are like family, so this is great information. Fortunately, ours are always indoors. Great pictures, too. The video... is heart-breaking and heart-warming. It gave me chills. Voted up, awesome, shared.

Kathy from Independence, Kansas on August 05, 2012:

Hi Angela Michelle. Oh, you've touched my very core with this one. I am sorry about Marley. Believe me when I tell you that I know how it feels to realize that a dearly loved kitty companion has been disgnosed with FeLV. It is like your breath is suddenly taken away. This hub is very sensitive and so well written. It is so important to make sure that our cats no longer roam the streets and neighbors' yards because, it is a fact; infections, diseases and other disastrous possibilities are out there, endangering our cats' lives. Over the last decade; we;ve lost Little Girl, Tucker, Yellow Guy, Barney, BobCat, Scamp, and, most recently, Handsome to complications as a result of FeLV. They were all rescued cats in SE Kansas..abandoned, left to fend for themselves. We gave them wonderfully loved lives but, in the end; it's very difficult to beat this disease. It is so invasive. Your video is touching. It is wonderful that you've set up Marley's Fund to help other cats . you have my deepest sympathy and undestanding and gratitude for placing this very helpful information on Hub Pages. Kathy