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Feline Immunodeficiency Virus (FIV)

FIV Overview

• A complex retrovirus that causes immunodeficiency disease in domestic cats
• “Immunodeficiency” is the medical term for inability to develop a normal immune response
• Feline immunodeficiency virus (FIV) is in the same genus (Lentivirus) of viruses as human immunodeficiency virus (HIV), the causative agent of acquired immunodeficiency syndrome (AIDS) in people

Genetics

• No genetic susceptibility for infection
• Genetics may play a role in progression and severity of disease

Mean Age and Range

• Likelihood of infection increases with age
• Mean age—5 years of age at time of diagnosis

Predominant Sex

• Male—more aggressive; more likely to roam (increasing exposure to virus)

Signs/Observed Changes in the Pet

• Diverse signs owing to the decreased ability to develop a normal immune response (that is, the immunosuppressive nature of infection)
• Associated disease cannot be distinguished clinically from feline leukemia virus (FeLV)-associated immunodeficiencies
• Recurrent minor illnesses, especially with upper respiratory and gastrointestinal signs
• Enlarged lymph nodes (known as “lymphadenomegaly”)—mild to moderate
• Inflammation of the gums (known as “gingivitis”), of the mouth (known as “stomatitis”), and/or of the tissues surrounding and supporting the teeth (known as “periodontitis”), seen in 25% to 50% of cases
• Upper respiratory tract disease seen in 30% of cases—inflammation of the nose (known as “rhinitis”); inflammation of the moist tissues of the eye (known as “conjunctivitis”); inflammation of the cornea (known as “keratitis”)—the cornea is the clear part of the eye, located in the front of the eyeball; often associated with feline herpesvirus and calicivirus infections
• Long-term (chronic) kidney insufficiency due to immune-mediated damage to the kidneys
• Persistent diarrhea, seen in 10–20% of cases
• Long-term (chronic), non-responsive, or recurrent infections of the external ear and skin—from bacterial or fungal infections
• Fever and wasting—especially in later stage
• Eye disease—inflammation of the front part of the eye, including the iris (known as “anterior uveitis”); disease of the eye, in which the pressure within the eye is increased (known as “glaucoma”)
• Cancer (such as lymphoma; “lymphoma” is a type of cancer that develops from lymphoid tissue, including lymphocytes, a type of white-blood cell formed in lymphatic tissues throughout the body)
• Nervous system abnormalities—disruption of normal sleep patterns; behavioral changes (such as pacing and aggression); disorders usually affecting the nerves to the legs and paws (known as “peripheral neuropathies”)

Causes

• Cat-to-cat transmission; usually by bite wounds
• Occasional transmission of the virus at the time of birth
• Sexual transmission uncommon, although feline immunodeficiency virus has been detected in semen

Risk Factors

• Male
• Free-roaming cat

Treatment
Health Care

• Outpatient sufficient for most pets
• Inpatient—with severe secondary infections, until condition is stable
• Primary consideration—manage secondary and opportunistic infections; “opportunistic infections” are infections caused by organisms that usually do not cause disease, but are able to cause disease because the cat's body and/or immune system has been weakened, in this case by the feline immunodeficiency virus infection
• Supportive treatment—fluids and nutritional supplements, as necessary

Activity

• Normal

Diet

• Normal
• Diarrhea, kidney disease, or long-term (chronic) wasting—special diet, as necessary

Surgery

• Dental cleaning, tooth extraction, biopsy of the gums
• Biopsy or surgical removal of tumors

Medications

• Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive
• Zidovudine (Retrovir)—direct antiviral agent; most effective against sudden (acute) infection; monitor for bone-marrow toxicity
• Medications to alter the immune response (known as “immunomodulatory drugs”)—may alleviate some clinical signs; may increase survival rates and improve clinical status; examples include interferon (Roferon); feline omega-interferon (Virbagen Omega); also try Propionibacterium acnes (ImmunoRegulin), or acemannan (Carrisyn)
• Antibiotic or antifungal drugs—useful for overgrowth of bacteria or fungi; prolonged therapy or high dosages may be required; examples include metronidazole and clindamycin
• Medications to decrease the immune response (such as steroids or gold salts)—judicious, but aggressive use may help control immune-mediated inflammation
• Short-term appetite stimulation: diazepam or oxazepam; more prolonged appetite stimulation and reversal of extreme weight loss with muscle wasting (known as “cachexia”): anabolic steroids or megestrol acetate; efficacy in feline immunodeficiency virus–positive cats is unknown
• Steroids applied directly to the eye (topical steroids)—for inflammation of the front part of the eye, including the iris (anterior uveitis); long-term response may be incomplete or poor
• Yearly vaccination for respiratory and intestinal viruses with inactivated vaccines is recommended

Follow-Up Care
Patient Monitoring

• Varies according to secondary infections and other manifestations of disease

Preventions and Avoidance

• Prevent contact with feline immunodeficiency virus–positive cats
• Quarantine and test incoming cats for FIV before introducing into households currently with one or more cats
• Vaccine
• Inactivated whole virus vaccine (Fel-O-Vax FIV, Fort Dodge Animal Health)
• Cannot distinguish between vaccinated and FIV-infected cats with antibody assays; virus detection by polymerase chain reaction (PCR) is inconsistent—makes diagnosis of disease difficult; newly developed ELISA testing may be useful in determining true FIV infection status
• Discuss the use of the vaccine with your cat's veterinarian

Possible Complications

• Recurrent infections
• Wasting
• Death

Expected Course and Prognosis

• Within the first 2 years after diagnosis or 4.5–6 years after the estimated time of infection, about 20% of cats die, but over 50% remain with no clinical signs of disease
• In late stages of disease (wasting and frequent or severe opportunistic infections), life expectancy is less than 1 year
• Inflammation of the gums (gingivitis) and mouth (stomatitis)—may not respond to treatment or may be difficult to treat

Key Points

• Feline immunodeficiency virus infection is slowly progressive, and infected cats may remain healthy for years
• Cats with clinical signs will have recurrent or long-term (chronic) health problems that require medical attention
• Keep FIV-infected cats indoors to protect them from exposure to secondary disease-causing agents and to prevent spread of FIV to other cats