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.

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.