What are the Clinical Signs of Disease
The clinical signs of disease are going to be variable because so many body systems can be affected. Loss of appetite, fever, weight loss, and weakness are the first signs most commonly seen in infected cats.
It is estimated that 1-2% of apparently healthy cats are infected with FeLV.
Serologic (blood) tests are commonly used to test both asymptomatic and symptomatic cats for FeLV antigen.
The ELISA test can be performed in veterinarians’ offices. If the ELISA test is positive, a confirmatory test should be done.
One confirmatory test is the immunofluorescent antibody (IFA) test, which uses blood smeared on a slide and is performed in special diagnostic laboratories.
Fluorescently-tagged antibody made in the laboratory reacts with the FeLV antigen in the blood and fluoresces when viewed through a special microscope.
A poymerase chain reaction (PCR) test is also available which can be helpful if the ELISA test and confirmatory test do not agree.