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FELINE IMMUNODEFICIENCY VIRUS (FIV)

Note for Pet Owners:

This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

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Description
Feline immunodeficiency virus (FIV) is often referred to as the cat equivalent of human HIV (AIDS). It was first identified in 1987 but it is known from positive testing of older blood samples that cats were infected many years earlier - from 1968.

The FIV virus infects white blood cells - mainly lymphocytes and peritoneal macrophages, resulting in  immune deficiency and rendering the individual unable to fight off infections or to overcome cancers.

Cause
FIV is caused by a Retrovirus - a Lentivirus, similar to the virus that causes Equine Infectious Anaemia. The virus is transmitted mainly through bites as the virus is present in saliva and blood, there is some evidence that it may be sexually transmitted, and in pregnant queens the virus can be transmitted to unborn kittens across the placenta, and it can also be transmitted in the milk of lactating queens. Similar,but genetically different lentiviruses are known to occur in wild cats including lions, pumas, panthers and snow leopards. 

Breed Occurrence
There is no specific breed incidence. Adult males that are allowed to roam are more likely to be infected than females and cats kept indoors.

FIV is common and based upon blood testing the virus is reported (according to some references) to be present in 1-4% of apparently healthy cats in the USA and 12% of healthy cats in Japan; and in 44% of sick cats in Japan and 10-14% of sick cats in the USA.

Cats usually develop secondary infections when they are over 5 years of age.

Signs

Cats can carry FIV without showing any signs. When signs occur  they are not specific to FIV and they may be due to the virus or due to secondary disease resulting because of the reduced immunity. The typical history is one of recurrent infections and signs including :

  • Gingivitis (inflammation of the gum margins)
  • Stomatitis (inflammation of the mucous membranes of the mouth)
  • Chronic respiratory infection (eg cat flu)
  • Chronic diarrhoea
  • Chronic skin infections
  • Enlarged lymph nodes
  • General depression
  • A high body temperature
  • Weight loss - wasting disease, particularly in the late phase of the disease
  • Nervous signs - due to the FIV itself
    • Behavioral changes
    • Fits - seizures
    • muscle twitches
  • Eye disorders - glaucoma, uveitis
  • Development of neoplastic disease (cancer) - eg lymphoma, leukaemia.
  • Death - once clinical signs occur the expected survival time is less than 1 year.

FIV infection should be suspected when other infectious diseases occur including the following :

  • Feline leukaemia virus FeLV
  • Toxoplasmosis - causes ocular lesions eg uveitis
  • Feline herpesvirus 
  • Feline calicivirus
  • Haemobartonellosis

Complications
The immune deficiency eventually results in secondary infections which the body can not overcome.

Diagnosis
Diagnosis is confirmed by blood tests using a variety of different techniques :

  • ELISA tests - can miss early cases before antibodies are produced. Also false positive and false negative results can occur
  • Indirect Immunofluorescence (IFA) tests - expensive
  • Immunoblotting tests - expensive
  • Virus isolation from blood - research
  • Polymerase chain reaction to detect  proviral DNA - research

Treatment
 Prevention - infected cats should be isolated. Cats should be screened for FIV before they are introduced into a home of cattery.

There is no vaccine against FIV at this time.

There are some antiviral preparations which have been reported to produce beneficial improvements in cats with FIV - but they do not cure the cats, and they are toxic causing both anaemia and liver damage :

  • Azidothymidine (AZT) 
  • 9-2 phosphonomethoxyethyladenine (PMEA)

Treatment of secondary problems in FIV patients has included the use of the following :

  • Antibiotics for bacterial infections
  • Antifungal drugs . However griseofulvin must not be used for cats with fungal infections - but this causes severe depression in neutrophil numbers
  • Corticosteroids 
  • Fluid therapy to reverse dehydration
  • Anabolic steroids to reverse the catabolic state and weight loss
  • Vitamin supplementation in cats with poor food intake

Prognosis
Poor once clinical signs occur

Long term problems

Chronic, recurrent  infections and other disorders

 

Updated October 2013