Feline Leukemia Virus (FeLV)

April 16, 2018
 Feline Leukemia Virus (FeLV)

This blog continues our series on vaccinations – why do your pets need them, and what diseases can they prevent? Today we’ll dive into learning about Feline Leukemia Virus, or FeLV, which can be prevented by a vaccine given to young kittens.

FeLV is a retrovirus that affects kittens and cats. Other related retroviruses are Feline Immunodeficiency Virus (FIV) and Human Immunodeficiency Virus (HIV) – but only cats can get FeLV (humans are not at risk).

Is feline leukemia virus common?

Approximately 2-3% of otherwise healthy cats will contract FeLV. While that number may seem small at first, it represents around 2 million cats in the U.S., making FeLV one of the most common infectious diseases in cats. Kittens are more susceptible to the disease than adult cats, and males tend to get it more often than females. Cats that live outside or regularly go outside are more at risk for infection.

How does a cat get feline leukemia?

The feline leukemia virus is mostly found in saliva, so the disease spreads when cats groom each other, are bitten by infected cats, or, more rarely, when they share food or water bowls. The virus can also be spread by urine and feces, so cats can exchange the virus in litter boxes or bedding shared with other infected cats. Additionally, a mother cat passes the virus to her unborn kittens in the uterus or through milk.

For adult cats, it takes significant exposure to the virus to become sick, so usually one encounter won’t spread it. The disease is most often spread when sick cats interact regularly with other cats or bite them.

What happens when a cat gets FeLV?

FeLV can best be understood as an infection that leads to other problems. Thus, after initial exposure, it can be difficult to determine if your cat is sick. Some cats will not show any signs of the disease, while others may show symptoms 2-4 weeks after exposure. Signs of infection include lethargy, fever, gastrointestinal problems, and swollen lymph nodes. A tricky aspect of FeLV is that it doesn’t present the same in all cats. Some cats who were minimally exposed to the disease or who have strong immune systems will not get the virus. Some cats will develop a latent or regressive infection, meaning that their bodies will carry some of the FeLV virus, but the disease will remain in check, and they won’t be sick and won’t transmit it. Other cats will get a progressive infection, making them contagious and susceptible to the virus’s related diseases. (This progressive infection happens almost every time a kitten under 8 weeks of age is exposed to FeLV.)

What diseases does FeLV cause?

When a cat has an FeLV infection, she is more vulnerable to developing related diseases, which is why the virus is so dangerous. These diseases and problems may include:

  • Loss of appetite/weight loss
  • Persistent fever
  • Anemia, caused by the virus affecting bone marrow
  • Gastrointestinal diseases, including cancer of the stomach or intestines, and diarrhea, vomiting or anorexia • Reproductive/pregnancy problems, like abortions and stillbirths
  • Enlarged lymph nodes
  • Immune-mediated diseases, in which issues develop in kidneys or joints
  • Neurological problems, such as seizures, paralysis, blindness and balance problems
  • Eye, nose and mouth/gum diseases
  • Skin and coat problems
  • Platelet disorders/decrease
  • Cancer, which occurs in about 30% of cats infected with FeLV
  • Immunodeficiency and infections, in which the body can’t fight off bacterial, viral or fungal infections. Sometimes the first sign of FeLV in a cat is a recurring bacterial infection in the mouth, skin infections or respiratory infections.

How is FeLV diagnosed? How do I know if my cat has it?

Because the disease can cause so many different reactions, disorders and infections, it can be challenging for you or your vet to know if a cat is infected. If your vet suspects an infection, she will take a blood test and send it to an outside lab for review. Only this blood test can confirm FeLV.

How do I prevent my cat from getting feline leukemia?

The best way to protect your cat from FeLV is to get a vaccination. The current vaccines are not 100% effective, but they are the best line of defense. Cats who should get vaccinated include those who spend time outside, are boarded, or spend time with other cats who may be infected. Kittens should all be vaccinated. Adult cats need to be tested for FeLV before being vaccinated in case they are already carriers.

You can also work to prevent the disease by limiting your cat’s exposure to the virus. The best way to limit exposure, especially if you have only one cat, is to keep the cat indoors. For families with multiple cats, have all the cats tested for FeLV, and completely separate infected ones from uninfected ones. If one cat is diagnosed, disinfect all food bowls, litter boxes and bedding. Ensure any new cats are tested before introducing them to the household.

What should I do if my cat has feline leukemia?

Cats with feline leukemia can live for many years. First and foremost, keep infected cats indoors—both to limit their exposure to infection and to keep them from spreading the disease to other cats. Keep a close eye on your cat for signs of infection and other diseases. Your vet may use a different vaccination protocol or prescribe other medications. You’ll also need to treat your cat for the related infections or diseases as they arise.

If you would like to discuss the FeLV vaccination, have your cat tested, or review any other issues, please make an appointment with one of the experienced veterinarians at Animal Clinic of Woodruff.

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