North American Veterinary Licensing Examination (NAVLE) Practice Test

What is the standard confirmatory test for Feline Immunodeficiency Virus (FIV) after a positive screening test?

1. Western blot test

2. FeLV Antigen test

3. Rivalta test

4. FIV complement fixation test

The correct answer is: Western blot test

The standard confirmatory test for Feline Immunodeficiency Virus (FIV) after a positive screening test is the Western blot test. This method is highly specific and reliable for confirming the presence of antibodies to FIV in a cat's serum. The Western blot works by separating proteins based on their size and then identifying specific viral proteins associated with FIV, providing clear evidence of infection. When diagnosing FIV, screening tests such as enzyme-linked immunosorbent assays (ELISAs) may yield positive results due to cross-reactivity or other factors, which is why confirmation is critical. The Western blot helps to ensure that a correct diagnosis is made, differentiating true positives from false positives. The other tests listed do not provide the necessary confirmation for FIV. The FeLV Antigen test is specific to Feline Leukemia Virus and is unrelated to FIV testing. The Rivalta test is typically used for diagnostic purposes in certain cases of effusions, while the FIV complement fixation test is not routinely used for confirming FIV but rather for research or specific cases. Thus, the Western blot is the most appropriate choice for confirming FIV following a positive screening result.