Following a thorough medical history and physical exam, an FIV test can be performed at most veterinary hospitals using a serology test called an ELISA assay. Using a few drops of blood, this test detects the presence of antibodies to the virus. Most veterinarians recommend that the test be conducted on kittens older than 14 weeks of age.
A false positive is possible in kittens younger than 14 weeks, because FIV antibodies can be transmitted during nursing from an FIV positive mother and take time to leave the kitten's system. However, the virus itself also can be passed by nursing, which is another reason why kittens should be retested after 14 weeks of age.
Cats that are sick or showing clinical signs of disease will need to have blood tests done to detect any abnormalities. The virus can affect organs such as the kidneys and liver, as well as the bone marrow. Involvement of the bone marrow can cause abnormal development of red blood cells, white blood cells, and platelets.
