Immunodeficiency Virus (FIV) (Feline)

Feline immunodeficiency virus infects cats and can lead to immune suppression, opportunistic infections and cancer.

Common name: Feline immunodeficiency virus (FIV), Feline acquired immunodeficiency syndrome (FAIDS)
Scientific name: Feline immunodeficiency virus (FIV)

Diagnosis

Signalment
FIV can infect all cats, but intact male cats, because of their propensity for fighting, are more likely to be infected. While signs of the disease are most likely to be seen in adult cats, FIV infection often occurs in cats under 1 year of age.

Incidence/prevalence
Up to 4 percent of free-roaming or stray cats may be infected with the virus.

Geographic distribution
FIV can be found throughout the world. Prevalence is higher in areas with large populations of free-ranging cats.

Clinical signs (primary, most to least frequent, scientific term, synonyms)
Stomatitis (inflammation of the mouth), Neoplasia, Neurological signs.

Clinical signs (secondary, most to least frequent, scientific term, synonyms)
Weight loss, Inappetence, Diarrhea, Anemia.

Cause (scientific, common term)
Feline immunodeficiency virus, genus Lentivirus (retrovirus).

Organ systems affected (most to least affected)
Immune system, Mouth, Gastrointestinal tract, Hematopoietic, Lymph nodes, Brain.

Diagnostic tests
FIV antibody test (ELISA), Western blot (confirmatory), PCR test (confirmatory).

Differential DiagnosisOral disease, Gastroenteritis, Feline leukemia virus (FeLV), Lymphsarcoma.

Overview

Feline immunodeficiency virus (FIV) causes failure of the immune system in infected cats and can lead to secondary infections and cancer. The disease is also known as feline acquired immunodeficiency syndrome (FAIDS) because it is caused by a virus similar to, and can cause signs like those in humans infected with, the AIDS virus.

However, FIV is not contagious to people. The virus is spread by saliva, usually due to a bite wound from an infected cat. Any cat can be infected by the virus, but un-neutered male cats, because they are more likely to roam and fight, are most commonly affected by the disease.

After infection, a cat may show mild signs – often missed by the owner – such as decreased appetite, fever and swollen lymph nodes. These signs usually resolve within a few weeks. The cat may then show no signs for many years. However, once a cat is infected with FIV, they are infected for life.

Over time, the virus slowly destroys the cat's immune system and makes them more prone to developing various diseases and infections. Inflammation of the mouth (stomatitis) is the most common sign seen in infected cats. Other signs may include inappetence, weight loss, diarrhea, upper respiratory tract infections, anemia, and neurological disorders such as behavior changes, weakness and seizures. FIV-infected cats are also more prone to cancer, especially lymphoma.

Diagnosis is made by blood test. The test may be run on a healthy cat to screen for the infection or to help diagnose the cause of signs in a sick cat. An FIV vaccine is available, but it is generally reserved for cats at high risk for infection.

Treatment

Home Care
Because FIV-infected cats can spread the disease and are more prone to infections, they should be confined inside to avoid contact with free-roaming cats. (In addition, neutering a cat may reduce its desire to roam and fight.) Cats should be watched carefully for any signs of illness and be seen immediately by a veterinarian if such signs develop.

Professional Care
FIV can be diagnosed only by a veterinarian using blood tests. Treatment depends on the cat's health status. For cats that are not currently ill, the veterinarian may prescribe medications to protect their immune system. If a cat is already ill, initial treatment would be aimed at treating any infections or other conditions the cat has developed and monitoring for any diseases that may develop in the future.

Action
Neutering cats and keeping them indoors are the best ways to prevent contact with infected cats. Cats who are infected with FIV need lifelong veterinary care.

Outcome
Cats with FIV may remain healthy for many years before signs of illness develop. Some cats may live a full lifespan. However, once signs develop, FIV-infected cats need constant attention and veterinary care for the remainder of their lives.

References/Additional Readings

Hartmann K. Feline Immunodeficiency Virus Infection and Related Diseases. In: Ettinger S.J., Feldman E.C., eds. Textbook of Veterinary Internal Medicine: Diseases of the Dog and Cat, 6rd Ed. St. Louis: Elsevier Saunders, 2006; 659-896.

Taylor K. Feline Immunodeficiency Virus Infection. In: Côté, E., ed. Clinical Veterinary Advisor: Dogs and Cats. St Louis: Mosby Elsevier, 2007; 376-378.

Author

Eric Dunayer, MS, VMD

DABT, DABVT

Editor

Steven Hansen, DVM, MS, MBA

DABVT, DABT
© 2007. The American Society for the Prevention of Cruelty to Animals (ASPCA)