Cat Leukemia: Symptoms, Testing and Prevention

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Although cat leukemia, also known as feline leukemia virus or FeLV, can be a difficult virus to manage, pets with it can still live happy, relatively long lives. Understanding feline leukemia symptoms can help you better care for a cat with this disease. Additionally, by being familiar with FeLV itself, you may be able to detect it sooner or prevent it altogether.

What Is Cat Leukemia? Is it Contagious?

According to the College of Veterinary Medicine at Cornell University, FeLV affects 2% to 3% of all healthy cats in the United States and up to 30% of cats who are sick or high risk. It's an infectious & contagious viral disease that's spread between cats, mostly through saliva and/or blood contact. FeLV can also be spread through urine and feces, and from a mother cat to her kitten in utero or through the mother's milk.

While FeLV can be contracted through fighting, it's better known as a "loving disease" — cats can spread it by rubbing noses and grooming each other. Note: A cat with FeLV can still spread the disease if they appear perfectly healthy.

FeLV is one of the leading causes of death among cats in the U.S., says Fetch by WebMD, outpaced only by trauma-related deaths. Fortunately, the incidence of FeLV has decreased significantly thanks to early detection, broader awareness of the signs and an effective vaccine.

What Are the Feline Leukemia Symptoms?

FeLV infections can be tricky for two main reasons: the virus attacks many systems in the body, and the signs vary depending on which system is affected. It is one of the most common causes of cancer in cats and can cause blood disorders. Feline leukemia weakens the immune system of an affected cat, leaving them susceptible to secondary infections.

A cat who's been recently infected may not show signs at all; however, over time, their health will slowly decline due to repeated infections or cancer. Cats with feline leukemia may demonstrate:

  • Weight loss
  • Poor appetite
  • Unkempt fur or poor hair coat
  • Persistent or recurrent fevers
  • Swollen lymph nodes
  • Pale or inflamed gums
  • Eye problems
  • Seizures
  • Chronic diarrhea or runny stools

Recurrent infections of the skin, bladder, nose and/or eyes are also common signs of cat leukemia.

Long-haired cat with green eyes rests on a human bed.

How Is Cat Leukemia Diagnosed?

If your veterinarian suspects your cat has FeLV, they can be screened through a simple ELISA snap blood test. If your veterinarian uses a reference laboratory, snap test results can be available within 24 hours. In some instances, this test can also be performed right in the office while you wait.

The snap test detects the virus in the blood; however, it is not 100 percent accurate. If a cat tests positive for FeLV, another blood sample must be sent to the lab to confirm infection through an IFA test (immunofluorescent antibody assay: a scientific test to look for specific antibodies that are present with FeLV). In some cases, a PCR (polymerase chain reaction) blood test is run as well. Your vet will be the best resource on which test is right for your cat.

What If My Cat Tests Positive for FeLV?

First thing's first: Do not panic. One positive test result doesn't necessarily mean your cat has FeLV. For example, false-positive results can occur in kittens exposed to the virus without them actually being infected. The American Association of Feline Practitioners recommends testing kittens, and advises pet parents to isolate any kitten who tests positive from other cats as a preventive measure. The kitten should be retested one month later, at 6 months of age, and again at 1 year of age.

If your older feline companion tests positive on the snap test, you'll also need to isolate them from other cats to prevent any spread of disease. Then, talk to your vet about having the snap test rerun and the IFA test run immediately. From this process, you can expect two main outcomes:

  • If both tests are positive, then your cat is likely infected with FeLV.
  • If the snap test is positive but the IFA test is negative, then your cat has been exposed but may be able to fight off the infection. Isolate your cat from other cats and have them retested in 30 to 60 days.

Based on the combined result of these tests, your vet will be able to make the most accurate recommendation regarding what to do next.

What Is the Treatment for Cat Leukemia?

There is no definitive cure for FeLV; however, with the right care, cats with the disease can live relatively long periods without feeling ill. Still, it's important that your cat stays under the close supervision of a vet who can promptly head off any problems, such as complications from secondary infections, to ensure they stay as healthy as possible. Twice yearly vet examinations are recommended, which may include annual or biannual blood or urine tests.

As FeLV can be easily spread to other cats, it's crucial that pets who are infected stay strictly indoors, ideally in a home where they're the only cat. Cats with FeLV may be more affected by stressful environments. Providing indoor enrichment, such as adding toys or new elements to their play space, can help reduce stress. Also, consider having a vet come to your home to suggest ways you can make the space more soothing for a cat with FeLV.

Because they have a weakened immune system, cats with FeLV should not be fed raw food, but instead a complete and balanced dry and/or canned food.

Can Cat Leukemia Be Prevented?

Yes, cat leukemia can be prevented through vaccination and by keeping your pet indoors and away from other infected animals. If your cat does go outdoors, protect them by keeping them on a leash or providing an enclosed outdoor structure. The FeLV vaccine is considered a lifestyle vaccine, so talk with your vet about its pros and cons. You can make the decision together regarding if it's right for your cat.

While it can be emotionally taxing to receive a cat leukemia diagnosis, it's important to stay calm while you put together a plan with your veterinarian. The best course of action you can take is to follow their advice to a T.

Contributor Bio

Dr. Sarah Wooten

Dr. Sarah Wooten

Dr. Sarah Wooten graduated from UC Davis School of Veterinary Medicine in 2002. A member of the American Society of Veterinary Journalists, Dr. Wooten divides her professional time between small animal practice in Greeley, Colorado, public speaking on associate issues, leadership, and client communication, and writing. She enjoys camping with her family, skiing, SCUBA, and participating in triathlons.

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