Feline Foamy Virus Infection in Cats


PetMD Editorial

Published Apr. 23, 2010

Feline foamy virus (FeFV) is a complex retrovirus (uses RNA as its DNA) that infects cats, apparently without causing disease. Some strains, however, induce differentiated lymphocytes to burst, suggesting a potential impact on the cat's immune function. Part of the Spumavirus genus, FeFV is relatively rare and is more prevalent in free-roaming cats. The prevalence of the virus in cats also increases with age.

Symptoms and Types

Most FeFV-positive cats are asymptomatic and in good health. However, some experts suggest that the infection is linked with myeloproliferative disease and chronic progressive polyarthritis, possibly due to the high likelihood of co-infection with the feline immunodeficiency virus (FIV). In these cases, the cat will demonstrate swollen joints, abnormal gait, and enlarged lymph nodes.


The way FeFV is transmitted is somewhat under dispute. The high prevalence of infection in some cat populations suggests casual contact may play a role in transmission, but this has not been demonstrated experimentally. Also, since free-roaming cats are at greater risk of FeFV infection, it may be transmitted through bites. It, too, has been discovered to transmit frequently from infected queens to their offspring, probably while still in the womb.

Co-infections with FIV and FeLV are fairly common, perhaps due to shared transmission modes and risk factors. Despite this, FeFV co-infection has not been proven to enhance early development of FIV infections.


You will need to give a thorough history of your cat’s health to your veterinarian, including the onset and nature of the symptoms. He or she will then perform a complete physical examination as well as a complete blood count, biochemistry profile, urinalysis, and electrolyte panel.

A blood sample may be taken for serologic testing, which assist in identifying FeFV antibodies.  However, this testing is not readily available and not particularly useful because the correlation between FeFV infection and the disease is so tenuous.  Veterinarians may also examine joint fluid from cats with chronic progressive polyarthritis.


Currently there is no course of treatment for cats with FeFV infections, except for prescribing immunosuppressive medications to those with chronic progressive polyarthritis. Caution must be used with cats that are also infected with FIV or FeLV.

Living and Management

Adverse reactions are unlikely with cats only suffering from FeFV. Animals that also have chronic progressive polyarthritis, on the other hand, often have a poor prognosis for long-term recovery.

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