Feline Leukemia (FeLV) is the most common fatal infectious disease in cats.   Symptoms can include weight loss, diarrhea, vomiting, breathing difficulties, inability to ward off other diseases, blood in the stool, excessive drinking and urination.  There is no accepted cure (however, see web links below), but there are effective vaccines.

The FeLV virus attacks bone marrow cells, and red and white blood cells (the name is taken from changes made by the virus to white blood cells referred to as leukemia).  Once infected the virus can remain dormant in the host cells, or it can begin to replicate itself.  Some cats are completely immune to the virus, some will carry the virus but not demonstrate any effects, and almost 1/3 of exposed cats will succumb to the virus.  Most common of these diseases are:  cancer of the white blood cells (leukemia), other cancers, respiratory infections,  diseases of the liver and kidney, and other diseases brought on by a degrading of the immune system.

The virus is spread through direct contact with an FeLV positive cat’s body fluids or saliva.  It is disputed if the virus can live long enough outside of its host to spread itself from food or water bowls, or from a litter box.  In any event, all cats owners should take precautions to protect their cats from the virus.  These include:

  • A periodic (at least yearly), exam by the vet that includes testing for the virus.
  • Vaccination/boosters for the Feline Leukemia Virus, especially if your cat is an “outdoors” cat.
  • Indoor cats are susceptible if they “escape” and come in contact with another cat.
  • If you bring a new cat into the household have it thoroughly tested before exposing it to other cats.
  • The best cure is prevention – get your cat vaccinated if there is any possibility of it coming into contact other cats.

Those cats who have succumbed to the virus may not demonstrate any signs of disease for up to a year.  They may live for as little as a few weeks, but probably not any longer than 3 years after their infection.  But, even though they do not exhibit any signs, they will still transmit the disease to other cats – therefore the importance of a periodic test (or, even better, vaccination).  Kittens of infected cats will most likely test positive for the virus, but signs of disease may not appear until later in their life.

Get your cat(s) examined and vaccinated.  While there is no accepted cure for FeLV, some of the following web sites discuss possible treatments:

FeLV Web Site Links


Feline Leukemia Treatments Page (www.angelfire.com/il/felv) mission is:  “Our mission in presenting the information on these web pages is intended to help those whose feline babies are not responding to traditional veterinary methods of treating feline leukemia. People should be forewarned that many vets are skeptical and will resist using these newer treatments. We urge folks that encounter such opposition to seek out another vet that is willing to administer these medications….”