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WITNESS® FeLV Feline Leukemia Antigen Test Kit

Affordable and easy to interpret—it delivers rapid results, can be stored at room temperature, and is 100% sensitive (95% confidence interval: 94.3% - 100%)!


WITNESS® FeLV is a convenient, easy-to-use, in-house test that detects the presence of the feline leukemia virus antigen that is found in high levels in infected cats. Antigen test results are not affected by FeLV vaccination or maternal antibodies. Kittens can be tested at any age.

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  • No Refrigeration
    WITNESS® FeLV has a 12-month shelf life at room temperature.

    No Snapping and No Monitoring
    RIM™ (Rapid ImmunoMigration) technology allows for a one-step process, as opposed to the ELISA method. So unlike with other in-house tests, you don’t lose time waiting to snap. Plus, you only need one drop of sample (anticoagulated whole blood, serum, or plasma).

    Rapid Results
    With accurate results in 10 minutes or less, you can give your clients the immediate test results they want, giving them peace of mind sooner or getting your patients on a management plan earlier.

    Easy to Interpret
    You get simple-to-understand results, with no complex interpretation needed:

    • One line on the right = negative
    • Two lines = positive

    Backed by Zoetis Service and Support

    • Same level of customer support you’re accustomed to receiving
    • Available in 10-test kits

    WITNESS® FeLV Detail Aid

  • Sample Information
    A sample size of 0.05 mL should be used. An appropriate sample can be any one of the following:

    • Anticoagulated whole blood (blood that has been collected in an EDTA [purple top] or heparin [green top] tube)
    • Serum
    • Plasma

    Instructions for Use

    1. Open the foil pouch and place the test kit on a flat horizontal surface for the duration of the test.
    2. Using the supplied pipette*, transfer 1 drop of sample (or 0.05 mL) onto the sample well (window 1), and allow for the sample to be completely absorbed.
    3. Add 2 drops of buffer to the sample well (window 1).
    4. Wait 10 minutes for sample and buffer to migrate across the test kit into windows 2 and 3.
    5. Read test results. When the control line appears in window 3, the test was performed correctly.

    *It is important to use the pipette provided to ensure enough sample is dropped into the well for accurate results. 

    WITNESS® FeLV Test Procedure & Results

  • WITNESS® FeLV detects the presence of the FeLV antigen p27 in cats’ blood. The WITNESS® format is referred to as Rapid ImmunoMigration (RIM™). This technology is also sometimes referred to as lateral flow or rapid immunochromatography. WITNESS® tests perform well without refrigeration using an antigen-specific antibody labeled with colloidal gold. After the sample and buffer are added to the sample pad (window 1), any antigens in the sample migrate across a nitrocellulose membrane along with the gold-labeled antibody (conjugate) and form an antigen/antibody gold complex. A second antibody specific to the antigen binds the antigen/antibody gold complex at the test line. In a positive sample, this generates a pink to purple colored reaction line in window 2. Excess colloidal gold migrates across to the control line, where an antibody directed to the gold-labeled antibody binds to it. This causes formation of a pink to purple control line (window 3).

    A test result should always be interpreted in the context of all available clinical information and history for the cat being tested.


    WITNESS® FeLV Test Procedure
    WITNESS FeLC Test procedure


  • Do not use components after expiration date.
  • Refrigeration not required. Store the test kit at 2˚ to 25˚C (35˚ to 77˚F). Do not subject to extreme temperatures.
  • Use the test within 10 minutes after opening the sealed pouch.
  • Avoid touching or damaging the membrane at windows 1, 2, or 3.
  • Use a separate pipette for each sample.
  • Hold the pipette and buffer bottle vertically when dispensing sample and buffer.
  • Handle all samples as if capable of transmitting FeLV.
  • For veterinary use only.



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