FeLV and FIV are both members of the retroviridae family of RNA viruses4. FIV is a member of the
lentivirus genus, FeLV belongs to the subfamily orthoretrovirinae, geuns gammaretrovirus. Both cause
severe, often fatal diseases in domestic cats. Both infections occur worldwide with prevalences
varying by location5. The clinical signs are mainly caused by the cats’ immunodeficiency and the
resulting secondary infections, tumours, and haematological abnormalities. This is the reason why
underlying retrovirus infection is often overlooked. All cats should be tested for FIV and FeLV,
especially those that are sick with signs that might be related to FeLV and/or FIV infection or before
being introduced into a multiple-cat household6. Testing to identify infected cats is the most important
method for preventing viral transmission. Accurate and simple diagnostic tests for inclinic use are
therefore indispensable. A variety of different testing methods are available, including fast screening
tests for FeLV antigens and FIV antibodies in plasma, serum, or whole blood. In recent years, many
rapid test systems have been licensed for use in veterinary practice and have been compared in
previous studies. The preferred initial tests are fast-performing in-house tests, such as ELISA or
immunochromatographic tests7. They offer the advantage of speed and convenience. These tests detect
the presence of soluble FeLV p27 antigen and the presence of antibodies against FIV proteins (usually
against p24, core protein and/or gp40 transmembrane protein). However, the sensitivity and specificity
of each test format and the prevalence of the infectious agent in question must be considered when
interpreting test results8.