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Summary of Clinical Management of Feline Leukemia Virus

Summary of Clinical Management of Feline Leukemia Virus

Testing recommendations

Test before vaccination against FeLV.

Test all sick cats, regardless of age and previous test status.

Test newly acquired cats as soon as possible after they are acquired and repeat testing ≥30 days later.

Test cats ≥30 days after most recent risk of exposure.

Test cats considered at risk with an unknown infection status:

  • Regularly test cats that are spending time free-range outdoors.

  • Test cats that are living in a home with, or have been exposed to, FeLV-positive cats or cats of unknown FeLV status.

Cats that are candidates to become blood donors should be tested for FeLV antigen and DNA.

Cats that are potential breeding stock should be tested for FeLV antigen and DNA.

Vaccination recommendations

Kittens, as part of the initial vaccination series and one year later

Cats that roam outdoors

Cats in transient group situations such as foster homes or temporary colony housing

Cats living with known FeLV-positive cats or cats of unknown FeLV status

Note: All cats should be tested for FeLV before vaccination.

Testing considerations

Antigen tests do not detect previous vaccination.

A single testing protocol is difficult to recommend for all cats.

Infected cats may not show clinical signs of disease.

It is not always possible to determine infection status with a single test.

Positive results of a point-of-care (POC) ELISA for FeLV indicates the presence of viral antigen (p27. Confirmatory testing is ideal and should include FeLV quantitative real-time PCR assay. Other confirmatory FeLV tests include a different manufacturer’s POC test, referral laboratory microtiter antigen tests, and immunofluorescence assays (IFA).

IFA detects secondary viremia after bone marrow infection. IFA test interpretation can be subjective and performance among laboratories differs. This can lead to false positives and negatives. False negative IFA results can also occur in cats with leukopenia and in cats with regressive infection.

Regressive versus progressive infections may be further clarified via quantitative real-time PCR array.

Management of infected cats

Infected cats may have a good quality of life.

Although many cats die within 3 years of diagnosis, others remain subclinically affected for multiple years.

Preventive veterinary care, including frequent physical examination, laboratory monitoring, core vaccinations, spay or neuter surgery, dental prophylaxis, and parasite control, is essential.

Avoid transmission to other cats by preventing access to outdoors and other uninfected cats in the household.

Vaccinate and routinely test uninfected, in-contact cats.

Antiviral and immunotherapeutic treatments are described in early trials or anecdotal use; however, none has both wide availability and demonstrated clinical efficacy in controlled field studies.

Adapted from the Feline Retrovirus Management Guidelines, American Association of Feline Practitioners, 2020.