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Feline Leukemia Information

What is FeLV? 

FeLV stands for “Feline Leukemia Virus”. It is a contagious viral disease that weakens and suppresses a cat’s immune system, making FeLV positive cats more susceptible to common health issues, such as upper respiratory infections, dental disease, etc. In the United States, approximately 2-3% of the cat population will test positive for Feline Leukemia. 

How is FeLV spread? 

FeLV is spread from a positive cat to other cats through body secretions, including saliva, nasal secretions, urine, feces and milk from mother cats. This means that that FeLV can be spread through mutual grooming, bites, shared food/water bowls and litter boxes, and nursing. The virus does not survive very long outside of a cat’s body and can be easily killed with regular washing/ sanitizing. 

How do you know if a cat is FeLV positive? 

Prior to being made available for adoption, each cat at Homeward Animal Shelter has a blood test, called an ELISA test, ran to ensure they are negative for FeLV. When a cat tests positive for Feline Leukemia test, we do not automatically assume the cat has Feline Leukemia because the cat may have been recently exposed to the virus and their body may still be in the process of fighting it off. 

To determine if a cat is truly infected with FeLV, we send out a test called a polymerase chain reaction (PCR). If the PCR is positive, it means that the virus has moved into the cat’s genome (aka DNA) and the cat is considered positive for Feline Leukemia. The PCR test also tells us if the infection is regressive or progressive, which will impact the lifespan of the cat.

To better understand what that means, it's important to understand that the manner in which a cat's body responds to the FeLV virus leads to one of 3 immune responses: abortive, regressive, or progressive.

Abortive: the cat's body has had an effective immune response, destroying the virus and preventing it from becoming encapsulated in their genome. Many people will not even know this has happened, because the cat will test negative after exposure. This happens in roughly 20% of cats exposed to the virus, and is most common in cats exposed as adults, rather than kittens.

Regressive: the cat's body has had a partially effective immune response to the virus, and the virus ends up encapsulated in the cat's genome, but the immune system keeps the virus "in check". This occurs in 30-40% of cats that test positive for FeLV. Regressively infected cats may initially have a positive test and later on, have a negative test. During a regressive infection, a cat is NOT able to spread the disease to other cats, and is unlikely to experience symptoms of FeLV. However, because the virus is still in their genome, it IS possible for it to become reactivated due to medication or illness that suppresses the immune system. If this occurs, the cat is once again able to infect other cats and also more likely to eventually show FeLV-related symptoms; if this occurs, the cat has moved to a progressive infection.

Progressive: the cat's body has failed to provide an effective immune response and the virus has entered the cat's genome. Cats with progressive infections have the worst prognosis, and are likely to exhibit signs of FeLV at some point in their lives. Once a cat starts to show symptoms of FeLV, they are likely to decline quickly; however, they can live symptom free for weeks, months or even years before showing symptoms. This occurs in 30-40% of cases, and is most common in cats exposed as kittens. Unfortunately, kittens that are infected often live less than 1-2 years, while cats that acquire progressive infections as adults are more likely to live around 3 years after diagnosis.

 

Can there be “false positives” on tests? 

Yes. ELISA tests can have false positives if the cat is currently fighting off the virus (abortive infection). The ELISA tests is specifically detecting virus particles in the blood, and just because the test is positive, it does not mean they are actually infected. This is why we utilize a second test, the PCR, to get a clearer picture of their FeLV status. However, no test can guarantee 100% accuracy (although the PCR test gets close at 99.2% accuracy). It is recommended that a cat with contradicting FeLV ELISA and PCR results always be rechecked in 2-3 months to ensure the infection was abortive and not regressive.

Another test, called an IFA test, can be utilized to also determine the accuracy of the ELISA test. The PCR test, however, tells us if the infection is progressive or regressive, and is our preferred method of testing.

Can people or dogs get FeLV? 

No. FeLV is species-specific to cats and can only be transmitted from cat to cat; humans, dogs, and all other species of animals besides cats can not become infected with Feline Leukemia. 

Can FeLV positive cats live with FeLV negative cats? 

In general, FeLV positive cats should not live with FeLV negative cats, however, there is a vaccine that can be utilized to reduce the likelihood of transmission of FeLV from a positive cat to a negative cat.  As with many things in life, the vaccine is not a 100% guarantee that it will fully protect a negative cat, but most FeLV vaccines have a 85-90% efficacy rate. FeLV positive cats, however, can live with other FeLV positive cats without issue. 

What quality of life will a FeLV positive cat have? 

There is no way to determine if a cat has FeLV simply by looking at them. Most FeLV positive cats will live normal lives up until the disease becomes too much for their immune system. In the early stages, they appear healthy. However, over time, a cat with a progressive infection will have deteriorating health and/or may have health issues that wax and wane. Cats infected as adults are more likely to live healthier lives than cats who were infected as kittens. Sadly, cats infected as kittens have an average lifespan of just two years. 

Is there any special veterinary care needed? 

A FeLV positive cat will be more susceptible to illnesses, so any signs of illness should be examined by a veterinarian. A high quality diet, low-stress environment and regular veterinary care are beneficial to a FeLV positive cat. 

Symptoms of a cat whose FeLV infection is worsening include:

  • Loss of appetite
  • Progressive weight loss
  • Poor coat condition
  • Enlarged lymph nodes
  • Persistent fever
  • Pale gums and other mucus membranes
  • Inflammation of the gums (gingivitis) and mouth (stomatitis)
  • Infections of the skin, urinary bladder, and upper respiratory tract
  • Persistent diarrhea
  • Seizures, behavior changes, and other neurological disorders
  • A variety of eye conditions 

Is there a cure or treatment for FeLV? 

Unfortunately, there is no specific treatment or cure for FeLV. When illnesses arise, they are treated symptomatically. It’s important to be aware that FeLV positive cats will likely live shorter lifespans and your veterinarian will be able to provide you guidance through illnesses that may shorten the lifespan of a FeLV positive cat. 

What should you consider before adopting? 

One thing to keep in mind is that we cannot guarantee the lifespan of a FeLV positive cat. Some may only live a few months and others may live several years. Depending upon how quickly the infection spreads and how weakened the cat’s immune system becomes, FeLV positive cats may require more regular veterinary care. FeLV positive cats are special felines who deserve to live out their lives in a special home like yours! 

For more information, check out: 

https://www.vet.cornell.edu/departments/cornell-feline-health-center/health-information/feline-health-topics/feline-leukemia-virus

 

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