Virologists, experts in the study of viruses, recommend that cats who are tested for Feline Leukemia Virus (FeLV) and Feline Immunodeficiency Virus (FIV) have two consecutive tests that agree with each other. Furthermore, those two tests should be approximately two months apart.
Suppose that you adopt a new cat from your local humane shelter. Your veterinarian draws a small blood sample today and performs the tests. The IDEXX company manufactures a test device that checks for the evidence of both viruses simultaneously. Of course, the best possible outcome is for both FeLV and FIV to be negative.
Still, your new kitty isn’t out of the woods just yet.
Like most diseases, FeLV and FIV progress through recognized, usually-predictable stages. Because your shelter cat might not yet be in a stage that allows its disease to show up on a test, a retest is needed.
If he is negative on both parts two months later he needs no more testing until or unless risk factors arise. Risk factors can include exposure to cats known to be infected with FeLV and/or FIV, exposure to sick cats, encounters with cats of unknown status (especially fights) and signs of chronic illness.
On the other hand, if the first test shows a positive for either FeLV or FIV a retest in two months that is also positive bodes a guarded prognosis. For more details on the interpretation of FIV testing please read this post.
If the second test is negative we still don’t have two consecutive tests that agree (the first positive, the second negative). The next step is another test two months later. If it is negative the test will need to be repeated in approximately six months to be sure he stays negative.
If the second test is positive for either disease the usual next step is a confirmatory test sent to an outside laboratory. This step is especially important in the case of a cat with chronic illness.
See you tomorrow, Dr. Randolph.