Feline Leukemia Virus (FeLV)

Adult cat being held

Feline leukemia virus (FeLV) causes a highly contagious and potentially fatal retroviral infection that weakens a cat’s immune system, making her susceptible to illness and secondary infection. Feline leukemia is a very common disease. It is often called the “friendly cat” disease as it is commonly spread from cat to cat through casual contact, such as grooming or sharing food or water. Feline leukemia virus and Feline immunodeficiency virus (FIV) are among the most common infectious diseases in cats. FeLV is nothing to meow about! In a study of more than 18,000 cats, 2.3% of them were positive for FeLV.

While all cats are at risk, lifestyle, sex, and vaccination status all play an important part in reducing exposure to this contagious disease. The following will increase your cat’s risk of contracting FeLV:

  • Not having been vaccinated against feline leukemia
  • Spending time outside, unsupervised
  • Exposure to a cat or kitten whose infection status is unknown
  • Living in a multiple-cat household
  • Not having been spayed or neutered
  • Aggressive behavior toward other cats
  • Symptoms of oral disease
  • Past or present abscess wounds

Cats with feline leukemia do not always appear sick! In the early stages of the disease, most cats show few signs; the only way to know for sure if they are infected is through a simple blood test. As the disease advances, the following symptoms may occur:


Most veterinarians include a screen for feline leukemia as part of the routine tests a cat gets during her lifetime. The American Association of Feline Practitioners (AAFP) recommends testing cats for FeLV as follows:

  • Cats should be tested at appropriate intervals based on their risk
  • Cats and kittens entering a new household should be tested at introduction 
  • Cats exposed to an infected cat should be tested twice—at the time of exposure and 60 days later
  • Cats should be tested before they are vaccinated for FeLV
  • Cats with clinical signs should be tested

Your veterinarian can run a simple test to see if your cat has been infected with FeLV. If the result is negative, they may recommend protecting your cat from FeLV by having her vaccinated. The AAFP recommends vaccinating all kittens (because their future lifestyle may change), cats that go outdoors, cats that have direct contact with cats of unknown status, and cats that live with FeLV-positive cats.

If you cat tests positive for FeLV, it is NOT a death sentence! Cats with FeLV can live until a ripe old age; many infected senior cats pass as a result of problems not associated with their infection. The AAFP recommends the following for managing the healthy, FeLV-positive cat:

  • Spaying or neutering intact cats
  • Careful control of internal and external parasites
  • Keeping infected cats indoors
  • Twice-a-year visits to your veterinarian, paying close attention to lymph nodes and any changes in the mouth
  • Discussion with your veterinarian about vaccinations
  • Yearly blood tests that may include:
  • Chemistry tests to evaluate kidney, liver, and pancreatic function, as well as sugar levels
  • A complete blood count (CBC) to rule out blood-related conditions
  • Electrolyte tests to ensure your cat isn’t dehydrated or suffering from an electrolyte imbalance
  • Cardiac tests to rule out heart related issues

Make sure your cat is tested for FeLV, that you limit her exposure to other cats you don’t know, and talk to your veterinarian about whether or not your cat should be vaccinated against FeLV.

To find out more about this disease and how you can keep your cat healthy, visit http://www.kittytest.com/.

If you have any questions or concerns, you should always visit or call your veterinarian – they are your best resource to ensure the health and well-being of your pets.


Reviewed on: 
Thursday, August 14, 2014