This is a virus that is common in cats, affecting 3% of all cats nation-wide and up to 14% of high-risk cats, which include feral cats and outdoor pet cats.  We include FeLV vaccines in our core vaccine list because it is such a devastating disease and cats can get exposed quickly if they escape outside.

Infected cats shed very high number of virus in their respiratory secretions and saliva, and can also pass virus in their blood, urine, feces and milk.  The most common route of transmission is from grooming or bite wounds.  Mother cats can also pass the virus to their kittens during pregnancy or through nursing.  The virus does not live for very long outside the cat's body (usually 12-24 hours). 

The majority of cats exposed to FeLV will clear the virus and develop an immunity.  If a good immune response is not enough to clear the virus, it moves into the bone marrow and begins to replicate.  These cats may not show any symptoms of being infected, but can still transmit FeLV to other cats. 

We have a good in-house screening test for FeLV.  Cats that are actively mounting an immune response after being exposed to FeLV will show a positive response.  Since some of these cats will be able to clear the infection, we recommend re-testing them in 3 months to see if they are still positive.  A confirmation test can also be sent to the lab to see if your cat is indeed infected with FeLV permanently. 

The following are steps you can take to help prevent FeLV from infection your cat household.

1. Only adopt FeLV negative cats.  These tests are routinely done at the shelter and at the veterinarian.
   
2. Keep your cats indoors to prevent exposure from feral cats.
3. Vaccinate for FeLV in all kittens and any adult cats that may be at risk of exposure, especially indoor/outdoor cats.
4. If you have cats that go outdoors, we recommend annual testing for FeLV/FIV so you can know their status.

FeLV causes many different problems in cats which can occur months or even years following initial infection.  These secondary problems occur as the immune system begins to fail.  Symptoms to watch for include:

• Appetite loss
• Weight loss
• Dental disease and mouth infections
  
• Urinary tract infections
• Respiratory infections
• Problems with the eyes (squinting, trouble seeing, pawing at the eyes)
• Pale gums
• Persistent diarrhea (may be a symptom of lymphoma, which occurs in a greater frequency in FeLV positive cats)

• Enlarged lymph nodes (may be a symptom of lymphoma, which occurs in a greater frequency in FeLV positive cats)

• Persistent skin infections

Keeping your FeLV positive cat as healthy as possible will help delay the onset of secondary problems.  Suggestions include spaying and neutering, providing a nutritious diet, keeping cats current on vaccinations, and maintaining parasite control and preventative care such as dental cleanings and routine bloodwork.  Most cats with FeLV will live 1-3 years after diagnosis is made.  Usually secondary problems become too severe to allow the cats to have a good quality of life.

Unfortunately, many cats diagnosed with FeLV have been living in a house with other cats prior to their diagnosis.  Since FeLV is transmitted simply by grooming, unvaccinated cats are at risk for contracting FeLV.  Have all of your cats tested, and if possible house the infected cats separate from the non-infected ones.  Do not allow sharing of food bowls or litter boxes.  Proper vaccination should help prevent the spread of the disease to your other cats but no vaccine is proven 100% effective.  Do not bring any new cats into your household while you have a FeLV positive cat.