All About Feline Leukemia

Thirteen years ago, BCR opened its doors to welcome cats who tested positive for feline leukemia (FeLV).   Like blind cats, leukemia cats are not put up for adoption in shelters and rescues but are, instead, euthanized right away as they are considered unadoptable.  The FeLV cats who have come to BCR made it here because people thought they deserved a chance and went the extra mile to help them. 

Update:  July 13, 2024
 
Where feline leukemia (FeLV) is concerned, things are changing all the time, which is good.  We keep up with the latest research on how it’s spread, testing, and treatments to make sure we provide our cats the best care possible.
 
One of our favorite and most reliable sources of information is the Cornell College of Veterinary Medicine, which is on the front line of research on FeLV.  Through sources like this one, and our own experience, we have made some adjustments in how we handle FeLV, like medication and testing tools. We’ve also begun to utilize available vaccines for our non-FeLV cats for the past five years.
 
So, to give you the latest and most up-to-date information on FeLV, we want to share this information directly from the Cornell College of Veterinary Medicine:
 
Transmission: 

FeLV is transmitted primarily through saliva, nasal secretions, urine, and feces of infected cats. It can be spread through mutual grooming, shared food and water bowls, and bite wounds.
 
Affected Cats: 

Cats of all ages are susceptible, but kittens and younger cats are more vulnerable due to their developing immune systems. Outdoor cats are at higher risk.
 
Symptoms:
FeLV can cause a wide range of symptoms including:
        Persistent fever
        Loss of appetite and weight loss
        Lethargy and weakness
        Pale gums
        Enlarged lymph nodes
        Respiratory problems
        Persistent diarrhea
        Jaundice (yellowing of the gums and whites of the eyes)
 
Diagnosis:
FeLV is diagnosed through blood tests that detect viral proteins (antigens) or antibodies to the virus. Kittens born to infected mothers may initially test positive but can clear the infection as they mature.
 
Treatment:
There is no cure for FeLV, so treatment focuses on managing symptoms and preventing secondary infections. Supportive care such as fluids, antibiotics for infections, and nutritional support are common.
Prognosis: 
The prognosis for cats with FeLV depends on various factors including their immune response, overall health, and whether they develop secondary infections or cancers associated with the virus. Some cats can live for years with supportive care, while others may succumb to the disease within a few months.
 
Prevention: 

Preventing FeLV infection involves vaccination, spay/neuter, keeping infected cats separated from uninfected ones, and minimizing contact with potentially infected cats. Vaccination is recommended for kittens and cats at risk of exposure.
 
If you’d like to read more from Cornell, click this link.

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Original story:

There are many myths and misconceptions about FeLV around today so cat parents need to be in the know since it's the second leading cause of death in cats and the number one virus-causing death.  Based on our experiences with FeLV-positive cats, we'll share our observations about FeLV throughout this article.

FeLV is a viral infection that suppresses a cat's immune system and can lead to them getting cancer, anemia or any number of other infections.  While it can be deadly, about 70% of cats who are exposed to the virus resist infection.   Some experts say that the approximately 30% of cats who do develop FeLV die within three years of diagnosis.  At BCR, however, we have not found this to be true. Our FeLV cats have lived five years or more and three even made it to ten years old!  The good news is that there is an effective vaccine for leukemia that protects cats from getting it.  With the vaccine and more reliable testing in the last two decades, the prevalence of FeLV has actually gone down.  It’s been our experience that vaccinated cats can live with FeLV+ cats and stay healthy.

How do cats get FeLV?  Indoor-only cats have a very low risk of developing FeLV.  Some sources believe that it can be transmitted from an infected cat to an uninfected or unvaccinated one through saliva shared from bites or blood from fighting, grooming, shared food and water, and from urine and feces in a shared litter box.  An FeLV-positive mother cat can also give it to her kittens.  

Several years ago, BCR's Skittle suddenly tested positive for FeLV.  At that time, we had an IFA test done, which also came up positive.  A third PCR (DNA) test was also positive. We didn't know what was going on but have since then learned that a cat can be DNA positive for FeLV and it won't show up on regular testing until the leukemia decides to "activate" or become positive.  This is similar to people who carry a gene for a certain kind of cancer - like the BRAC gene for breast cancer - but they don't actually get cancer.  To be safe, we tested all the cats in Skittle's room, including his two brothers, Peanut and Jellybean.  Four cats tested positive, one being Peanut, but Jellybean was negative.  We then tested all the cats in Skittle's building and all of them were negative. The lesson here is that, just because your cat tests negative at your vet's office, he may some day later become positive.  Only the PCR test, which vets don't automatically do, will show if a cat has FeLV in his DNA. 

What signs of FeLV should you be looking for in your cat?  This comprehensive list is from petmd.com:

• Anemia
• Lethargy
• Progressive weight loss
• Susceptibility to infection
• Persistent diarrhea
• Infections of the external ear and skin and poor coat condition
• Fever (seen in about 50 percent of cases)
• Wobbly, uncoordinated or drunken-appearing gait or movement
• Generalized weakness
• Inflammation of the nose, the cornea, or the moist tissues of the eye
• Inflammation of the gums and/or mouth tissues (gingivitis/stomatitis)
• Lymphoma (the most common FELV-associated cancer)

Other possible symptoms, according to pets.webmd.com, are pale gums, a yellow color in the mouth and whites of the eyes, enlarged lymph nodes, breathing difficulty and reproductive problems.

If you and your vet suspect your cat might be FeLV positive, blood tests can be done to confirm it.  At BCR, we always insist on also a doing a quantum PCR test, which is really the most reliable  gold-standard for FELV tests.

There is no treatment for FeLV.   Instead, vets generally treat the secondary infections and cancers that can develop because of it.  Those treatments depend on the cat's condition and may include steroids, blood transfusions and supportive care.  Prevention is still the best option and getting your cats vaccinated is the most effective way of preventing FELV.  For kittens, the vet will start with a two-vaccine series across three or four weeks.  Then a year later the kittens get a booster.  After that FeLV shots are yearly.  Keeping cats indoors is still one of the best ways of keeping them safe from FeLV.

It's a sad fact that most cats who are diagnosed with FeLV won't live a long life, but if your cat tests positive, there are things you can do.  First and foremost is to stay in touch with your vet and watch your cat's health closely.  For FeLV-positive cats, it's especially important to make sure they are maintaining their weight and that any minor infections are treated quickly.  Make sure your cat is on a healthy and appropriate diet, too.


CLICK HERE to read the full pet.md article.