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Feline immunodeficiency virus


Synonym(s): feline immunodeficiency virus, FIV, formerly known as FTLV: feline T-lymphotropic lentivirus




  • Family: Retroviridae.
  • Group: Lentivirus.


  • Lenti - from Latin lenti meaning slow because of slow pathogenic process, ie long incubation period from infection to exhibition of clinical signs.

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Clinical Effects



  • By biting.
  • More common in male than female cats because male cats fight and are bitten more frequently.
  • Virus is excreted in the saliva.
  • Transplacental transmission is rare, unlike in HIV, presumably because of the different type of placenta in cats compared to humans.
  • Neonatal transmission may occur during the perinatal period when the queen licks her offspring or bites through the umbilicus or possibly via colostrum or milk.

Pathological effects

  • Unusual in that humoral immune response is not protective - all infected animals are seropositive and the detection of antibodies is the main method of diagnosis.
  • Cats infected with FIV are infected for life.
  • Generalized lymphadenopathy 4-6 weeks post-infection, may be missed in the field.
  • Most cats are then asymptomatic for years following infection.
  • As CD4+ T cell numbers fall immunodeficiency ensues, therefore many clinical signs possibly a consequence of secondary infections.
  • Gingivitis Gingivitis and stomatitis, pyrexia, chronic disease, recurrent infections.
  • B cell lymphomas Lymphoma.
  • Neurological signs in around 5% of FIV-infected cats.


Control via chemotherapies

  • Most therapy is symptomatic and supportive.
  • Use bactericidal rather than bacteristatic antibiotics.
  • The virustatica 3'-azido-2', 3'-dideoxythymidine (AZT) at 5 mg/kg every 12 hours for 3 weeks or 9-(2-phosphonylmethoxyethyl)adenine (PMEA) at 2.5 mg/kg every 12 hours for 3 weeks gave clinical improvement and improved FIV-related gingivitis. However, toxicity is a concern, with anemia, neutropenia Hematology: neutrophil and anorexia being reported.
  • FIV-positive cats more likely to experience neutropenia when treated with griseofulvin Griseofulvin than FIV-negative cats.
    Avoid griseofulvin in FIV-Positive cats.

Control via environment

  • Prevent contact of uninfected cats with infected cats (thus, cats kept permanently indoors have no opportunity to become infected).
  • Testing is vital to establish which cats are infected and which are not.
  • Cat breeders should insist on FIV-negative status before accepting outside queens or stud cats.
  • Since indirect transmission does not occur, FIV-infected cats can be safely boarded in the veterinary surgery or boarding cattery with no fear of transmission to other cats.


  • Fel-O-Vax FIV is available in US, Australia, New Zealand and Japan but is not recommended by AAFP and is not available in Europe.
  • Vaccination for other conditions (feline panleukopenia, cat flu, etc) should be continued as normal in the healthy FIV-positive cat. Should weigh risk of exposure to these pathogens.
  • Some concern that vaccination may, through lymphocyte activation, increase replication of FIV.

Other countermeasures

  • It has been suggested that neutering may reduce fighting behavior and thereby decrease the likelihood of FIV transmission.
  • Keep FIV-positive cats indoors so they are not a risk to other outdoor cats and so the FIV-positive cat will not be exposed to pathogens carried by other cats.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Hosie M J, Addie D, Belák S et al (2009) Feline immunodeficiency. ABCD guidelines on prevenetion and management. J Feline Med Surg 11 (7), 575-584 PubMed.
  • Levy J K, Crawford P C & Slater M R (2004) Effect of vaccination against feline immunodeficiency virus on results of serologic testing in cats. JAVMA 225 (10) 1558-1561 PubMed.
  • Muirden A (2002) Prevalence of feline leukaemia virus and antibodies to feline immunodeficiency virus and feline coronavirus in stray cats sent to an RSPCA hospital. Vet Rec 150 (20), 621-625 PubMed.
  • Uhl E W, Heaton-Jones T G, Pu R et al (2002) FIV vaccine development and its importance to veterinary and human medicine: a review FIV vaccine 2002 update and review. Vet Immunol Immunopathol 90 (3-4), 113-132 PubMed.
  • Nowotny N, Uthman A, Haas O A et al (1995) Is it possible to catch leukaemia from a cat? The Lancet 346 (8969), 252-253 PubMed.
  • Hartmann K, Donath A, Beer B et al (1992) Use of two virustatica (AZT, PMEA) in the treatment of FIV and of FeLV seropositive cats with clinical symptoms. Vet Immunol Immunopathol 35 (1-2), 167-175 PubMed.

Other sources of information

  • Hopper C D, Sparkes A H, Harbour D A (1994) Feline immunodeficiency virus. In: Feline Medicine and Therapeutics 2nd edn. Ed Chandler E A, Gaskell C J, Gaskell R M. Blackwell Science, Oxford, OX2 OEL. pp 488-505.
  • McCaw D L (1994) Advances in therapy for retroviral infections. In: Consultations in Feline Internal Medicine 2 Ed: August J R. pp 21-25.
  • Shelton G H (1994) Management of the feline immunodeficiency virus-positive patient. In: Consultations in Feline Internal Medicine 2 Ed: August J R. pp 27-31.
  • American Association of Feline Practitioners (AAFP):

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