Feline Immunodeficiency Virus (FIV)

Feline Immunodeficiency Virus (FIV)

By: Dr. Debra Primovic

Section: Veterinary Care In-depth

Diagnosis In-depth

Diagnostic tests must be performed to confirm the diagnosis of feline immunodeficiency virus and exclude other diseases that may cause similar symptoms. Some of the following diagnostic tests may be recommended:

  • A complete medical history and a thorough physical examination. Special attention is paid to mucous membrane color and lymph node size.

  • Blood test for feline immunodeficiency virus. The routine screening test is called the
    Enzyme-lined immunosorbent assay (ELISA). The ELISA detects anti-FIV antibodies in the serum or saliva. As mentioned earlier, Results can be difficult to interpret in cats less than six months of age. These tests will also be positive if the cat has been vaccinated for FIV. For this reason, only unvaccinated cats should be tested and every cat should be tested before the first FIV vaccination.



    If positive, a second test should be done to confirm FIV status using the Western blot or Polymerase chain reaction (PCR) test. The western blot test is considered to be definitive for FIV. If the initial screening test is positive but the western blot is negative, the cat is considered negative for FIV.

    False positive ELISA tests can occur in cats less than 6 months of age that still have antiboidies from their mothers or from their mothers milk (maternal or colostral antibodies), in cats that have been vaccinated and a few from test error.

    False negative ELISA tests can occur in cats that were recently infected and have not yet began to produce antibodies (it can take 8 weeks from exposure to have a positive test result). If you got your cat today and he is negative and he was exposed to a cat with FIV yesterday, it may be two months before he shows a positive test result. The other cause for false negative test results can occur in cats with end-stage FIV. These cats will have such severe immunodeficiency that their bodies will no longer make detectable antibody for the test.

  • Blood test for feline leukemia virus (FeLV), because FeLV infection can cause similar signs to FIV infection.

  • Blood test for feline infectious peritonitis (FIP).

  • Serum tests for toxoplasmosis and ehrlichiosis.

  • A complete blood count (CBC) to evaluate your cat for anemia, signs of inflammation and blood platelet numbers.

  • A biopsy or fine needle aspirate, which is a sample collected by aspirating cells through a syringe and needle, of any solid tumors may be performed for microscopic analysis and diagnosis.

    Your veterinarian may recommend additional diagnostic tests to exclude or diagnose other conditions and to better understand the impact of FIV infection. These tests ensure optimal medical care and are selected on a case-by-case basis and may include:

  • Serum biochemistry tests to evaluate the general health of your cat and to determine the impact of FIV infection on other body systems such as the kidneys and liver. Serum biochemistry tests often are normal in cats with FIV infection.

  • Urinalysis to evaluate kidney function and identify protein loss in the urine or urinary tract infection. Urinalysis usually is normal in cats with FIV infection, but occasionally unless urinary tract infection may be present.

  • Thoracocentesis refers to the aspiration of accumulated fluid from the chest cavity using a needle and syringe. The fluid obtained is submitted for microscopic analysis to identify other diseases such as lymphosarcoma, pyothorax (bacterial infection in the chest cavity) or feline infectious peritonitis.

  • Abdominal paracentesis refers to the aspiration of accumulated fluid from the abdominal cavity using a needle and syringe. The fluid obtained is submitted for microscopic analysis to identify other diseases such as FIP and spread of cancer to the peritoneal cavity.

  • Chest X-rays may be taken if your cat has difficulty breathing or abnormalities are found on listening to the chest with a stethoscope. Chest X-rays may show evidence of secondary bacterial pneumonia in some cats with FIV infection.

  • Bone marrow aspiration and microscopic analysis may be recommended in some FIV-infected cats with some combination of low white cell count, anemia, and low platelet count.

  • Cerebrospinal fluid (CSF) analysis may be recommended in FIV-infected cats with clinical signs of nervous system disease. The CSF fluid also can be analyzed for the presence of antibodies against FIV, abnormally high numbers of inflammatory cells and high CSF protein concentration.

    Treatment In-depth

    Treatment of FIV infection must be individualized based on the severity of the condition and other factors that must be analyzed by your veterinarian. If your cat has no clinical signs, no treatment may be necessary. In this situation, regular follow-up visits to your veterinarian are important to ensure the condition does not progress. If immunodeficiency and secondary infection have developed, additional treatment will be necessary. Supportive care and symptomatic therapy are important and include:

  • Antibiotics for secondary bacterial infections

  • Nutritional support

  • Fluid therapy in dehydrated cats

  • Parasite control

  • Isolation from other cats that may have an infection

  • Biopsy and removal of tumors

    Several drugs that are used to treat people with human immunodeficiency virus (HIV) infection have been used in cats with FIV infection. Drugs used may include the following:

  • Zidovudine (AZT®) is an antiviral drug (a nucleoside analog) commonly used in human patients with AIDS that also has been used in FIV-infected cats. Treatment with AZT may result in clinical improvement, immune function, and quality of life. AZT has some potentially serious adverse effects and should be administered to FIV-infected cats under the supervision of a veterinarian experienced with its use.

  • Alpha interferon (Roferon®) may reduce viral replication in some infected cats. It is not licensed for use in cats, but some clinical studies found increased activity, increased appetite, improvement of blood abnormalities, increased clearance of virus and prolonged survival in treated cats.

  • Immunomodulators could be beneficial in cats with FIV infection by restoring immune function. Examples include Propionbacterium acnes (Immunoregulin®) and Acemannan (Carrisyn®).

  • 3TC (lamivudine) is another nucleoside analog used in human patients with AIDS that also has been used in some cats with FIV infection. Like AZT, its use is associated with potentially serious adverse effects and it should be administered to FIV-infected cats under the supervision of a veterinarian experienced with its use.

  • 9-(2-phosphonylmethoxylethyl) adenine (PMEA) is another drug that has been used in FIV-infected cats and has been reported to reduce the severity of chronic mouth infections in affected cats.

  • Bone marrow transplantation has been performed in a limited number of FIV-infected cats and is successful in restoring white blood cell counts in some instances. Infected cats, however, remain infected with FIV. This procedure is only available at a limited number of referral research institutions.

    Prognosis

    Most cats with FIV will live for months to years without symptoms. Most cats will eventually have enough viral replication that they will go into the terminal phase of the disease and develop secondary illness.

     
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