FIV: Feline Immunodeficiency Virus

Feline immunodeficiency virus (FIV) causes immunosuppression by attacking immune regulator cells, which may hinder a cat's ability to protect itself against infections caused by common bacteria, viruses, protozoa and fungi.

Prevalence

FIV infection occurs worldwide, with prevalence varying by location. Here is a look at the U.S. prevalence data:1

Transmission and Progression

• FIV is transmitted horizontally primarily through bite wounds, making aggressive male cats more susceptible to the disease.

• Vertical transmission has been documented, but is not a common mode of transmission, so kittens are not as likely to be infected as adults.
• Once a cat is infected with FIV, it will remain infected. FIV infection has three major stages that occur during the course of infection:
  1. The Acute Phase occurs during the first 4–6 weeks postexposure. This phase can be accompanied by transient illnesses such as fever, neutropenia and lymphadenopathy, but signs are often so mild that they go unnoticed by owners.
  2. The Asymptomatic Phase is a long period of clinical latency that usually lasts for many years. While clinical signs are uncommon, there is a high rate of viral replication, and immune function gradually deteriorates.
  3. The Acquired Immune Deficiency Syndrome (AIDS) Phase. This is a late stage of infection in which cats develop disease-associated weight loss, recurrent UTI, gingivitis, oral lesions, anemia, etc. A 2006 study showed that the survival rate for FIV-positive cats was 80% compared to controls at six years postdiagnosis.2 This suggests that most cats do not reach the AIDS phase of FIV infection.

Testing Guidelines from the American Association of Feline Practitioners (AAFP)

Despite the relatively high prevalence of FIV, a very small percentage of potentially infected cats are being tested. The AAFP recommends testing cats that fall into these categories:

• At risk—including cats that spend time outside, live with or come into contact with cats of unknown retrovirus status or present with bite wounds or evidence of fighting, etc.
• Sick—including cats with presenting signs such as lethargy, fever, vomiting, stomatitis, gingivitis and abscesses, and those without presenting signs that are ADR.
• New to household, regardless of age.

For a detailed overview of FIV and FeLV including signs, diagnosis and management, consult the AAFP Guidelines on Retrovirus Testing and Management. (6.2 MB)

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