FeLV: Feline Leukemia Virus

FeLV is a disease that inhibits the immune system through bone marrow suppression that may hinder a cat's ability to protect itself against infections caused by common bacteria, viruses, protozoa and fungi.

Prevalence

FeLV infection occurs worldwide, with prevalence varying by location.¹ FeLV is associated with illness and death of more cats than any other infectious agent.² Here is a look at the U.S. prevalence data.

Transmission and Progression

• FeLV is transmitted horizontally through body fluids such as saliva, urine and feces. It’s typically spread through the sharing of food and water bowls and can also be spread through bite wounds.
• Vertical transmission from mother to baby is also possible, either in utero or, more commonly, through nursing.

FeLV infection has been categorized into several potential outcomes that describe the relationship between the FeLV virus and the cat host:

• Transient infection is one in which the immune response clears the virus.
• Latent infection occurs when the immune system suppresses the virus to the point that it is harbored in the bone marrow and other sites without replicating or causing clinical signs.
• Persistent infection occurs when the cat’s immune system is overwhelmed by the virus.

Testing Guidelines from the AAFP

Despite the relatively high prevalence of FeLV, a very small percentage of potentially infected cats are being tested. The AAFP recommends testing cats that fall into these categories:

• At risk—including cats that spend time outside, live with or come into contact with cats of unknown retrovirus status or present with bite wounds or evidence of fighting, etc.
• Sick—including cats with presenting signs such as lethargy, fever, vomiting, stomatitis, gingivitis and abscesses, and those without presenting signs that are ADR.
• Newly adopted kittens and cats regardless of age.

For a detailed overview of FIV and FeLV including signs, diagnosis and management, consult the AAFP Guidelines on Retrovirus Testing. (7.3 MB)

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