Feline Immunodeficiency Virus (FIV) in Cats: A Comprehensive Guide

Feline immunodeficiency virus (FIV) is a lentivirus that affects domestic cats worldwide. It is very similar to human immunodeficiency virus (HIV), the virus that causes AIDS in humans. As the name suggests, FIV weakens the immune system of infected cats, making them more susceptible to other infections and diseases. Like HIV, there is currently no cure for FIV, but infected cats can live long and healthy lives with proper care and treatment. This comprehensive guide covers everything cat owners need to know about FIV in cats.

What is Feline Immunodeficiency Virus?

FIV is a retrovirus that infects and breaks down a cat’s immune system over time by attacking the white blood cells that normally protect the body from infection and disease. As the infection progresses, the cat’s immune system becomes weaker, leaving it vulnerable to various secondary infections, similar to AIDS in humans.

FIV is a lentivirus, which means it has a long incubation period. Years can pass between initial infection and the onset of identifiable symptoms. For this reason, FIV is sometimes referred to as “feline AIDS” because like human AIDS, the cat’s immune system slowly deteriorates over time after infection.

However, FIV is different from HIV in some key ways:

  • FIV is species-specific to felines. It cannot infect humans or dogs. Cats are the only natural hosts for FIV.
  • It is more difficult to transmit FIV between cats. The virus can only be spread through deep bite wounds, where the infected cat’s blood enters the bloodstream of another cat. Casual contact such as sharing food bowls does not transmit FIV.
  • FIV progresses more slowly than HIV. Most cats can live many years with FIV before developing advanced symptoms. With proper care and veterinary monitoring, FIV+ cats can live nearly normal lifespans.

How Do Cats Get Infected with FIV?

FIV is transmitted primarily through bite wounds, wherein an infected cat’s saliva passes directly into the bloodstream of another cat. This typically occurs through serious deep bite wounds sustained during territorial fighting between cats. The virus can also potentially spread from an infected mother cat to her kittens, either in the womb or through her milk.

Unlike with humans, FIV is not transmitted through:

  • Sharing food bowls, water bowls, or litter boxes with an infected cat
  • Grooming or casual play between cats
  • Licking/touching
  • Sneezing or coughing
  • Sexual contact

Because the main route of transmission is through bite wounds, free-roaming outdoor cats are at the highest risk of contracting FIV. Intact male cats who frequently fight with other males over territory are the most common carriers, though cats of any age, sex, or breed can become infected.

Indoor cats who do not fight are at very low risk of getting infected. Multi-cat households can safely have an FIV+ cat living among FIV-negative cats when proper precautions are taken (see tips below).

Signs and Symptoms of FIV

Acute Phase

When a cat is first infected with FIV, it may experience flu-like symptoms for a few weeks:

  • Fever
  • Lethargy
  • Swollen lymph nodes
  • Loss of appetite

These symptoms typically resolve on their own as the cat’s immune system produces antibodies to fight the virus. The cat then enters an extended asymptomatic period that can last many years.

Asymptomatic Phase

After the short acute phase, FIV enters a latent or dormant phase. An infected cat may remain completely asymptomatic for 3-5 years or longer before symptoms reappear.

During this lengthy asymptomatic period, the cat appears healthy but can still spread FIV to other cats through bites. This is why routine FIV testing is important even for healthy cats.

Secondary Infections

FIV slowly destroys the infected cat’s immune system over time. Eventually, the cat is no longer able to fight off other infections and diseases, leading to:

  • Persistent fever
  • Lethargy
  • Appetite loss
  • Weight loss
  • Poor coat condition
  • Chronic dental disease
  • Persistent diarrhea
  • Skin, urinary tract, respiratory infections
  • Cancer and other illness

The secondary infections are what ultimately prove fatal in cats with advanced stage FIV. With supportive veterinary care and medication, many FIV+ cats can live for years before reaching this point. But without treatment, progressive FIV infection leads to death typically within 2-5 years once symptoms reappear.

Diagnosing FIV in Cats

FIV is diagnosed through a simple blood test. The FIV antibody test checks for the presence of antibodies produced by the cat to fight FIV.

Veterinarians may recommend routine FIV testing:

  • For any new cat entering a household with other cats
  • For cats being adopted from shelters
  • As part of routine wellness exams for adult cats
  • If symptoms suggestive of FIV appear
  • Prior to administering certain vaccines

Cats under 6 months old may test falsely positive for maternal FIV antibodies acquired from their mother. Kittens should be retested after 6 months to confirm FIV status.

There are two main types of FIV tests:

  • ELISA (SNAP) test – This is the most common FIV test. It detects FIV antibodies in a small blood sample within minutes. Very accurate when positive, but false negatives are possible.
  • IFA test – The immunofluorescent assay test is more sensitive and may be recommended to confirm negative ELISA results. It requires sending a blood sample to a diagnostic laboratory.

Veterinarians may recommend retesting cats with suspected false negative results or periodically testing asymptomatic cats to monitor disease progression.

Treating and Managing FIV

While there is currently no cure or vaccine for FIV, infected cats can still live long, high-quality lives with appropriate care. Treatment goals focus on supporting immune function and preventing secondary infections.


  • Antibiotics – To treat bacterial, dental, and respiratory infections common in FIV+ cats.
  • Antiviral medication – Drugs like AZT (zidovudine) may be prescribed to cats with advanced FIV to slow disease progression.
  • Immune-modulating drugs – Medication to boost immune function may be beneficial in some cats.
  • Pain relievers – To treat discomfort associated with stomatitis, arthritis, and other conditions aggravated by FIV.
  • Supplements – Vitamins and nutritional supplements to support the immune system.

Veterinary Care

  • Regular checkups – At least every 6 months to monitor health and catch issues early.
  • Diagnostic testing -such as bloodwork and urinalysis to check organ function and screen for illnesses.
  • Dental care – Professional cleanings and extractions to prevent stomatitis.
  • Vaccinations -Core vaccines are still recommended for FIV+ cats. Avoid vaccines with inactive viruses.

Lifestyle and Nutrition

  • Keep the cat indoors to prevent injuries, infections, and transmitting FIV to other cats.
  • Feed a high-quality diet rich in vitamins and nutrients. Nutritional supplements may also be beneficial.
  • Minimize stress and changes to routine. Stress can accelerate disease progression.
  • Groom the cat regularly to check for skin issues and prevent mats, which harbor bacteria.
  • Have a separate litter box for an FIV+ cat. Scoop daily to keep clean.
  • Monitor weight closely. Unexplained weight loss may signal issues.
  • Provide mental stimulation and play to keep the cat active and engaged.

With this supportive care, many FIV+ cats enjoy several years of excellent quality of life before the most advanced symptoms appear. Early detection and treatment are key to managing this chronic retroviral disease.

Tips for Living with an FIV+ Cat

Caring for an FIV+ cat requires some special considerations but poses minimal risk to human owners or other household pets when basic precautions are followed.

No Risk to Humans

  • FIV cannot be transmitted from cats to humans. It is completely safe for immunocompromised people and families with small children to live with an FIV+ cat.

Minimal Risk to Other Household Pets

  • Dogs, rabbits, and other domestic pets cannot contract FIV. Only felines are at risk.
  • Other cats are unlikely to get infected provided the FIV+ cat does not fight or bite them.

Recommendations for Multi-Cat Homes

  • Get all cats in the household tested. Separate any FIV+ cats from uninfected cats.
  • Neuter all cats to reduce territorial fighting over mates.
  • Introduce new cats slowly and carefully. Monitor all interactions.
  • House FIV+ and negative cats in separate areas if fighting is an issue.
  • Use separate litter boxes, food bowls, etc. for FIV+ cats.
  • Take FIV+ cats to the vet in a separate carrier and exam room.

With care and monitoring, an FIV+ cat can safely remain in a home with other cats in most cases. The risks are very low for indoor-only cats housed in a peaceful environment.

Outlook for Cats with FIV

While FIV is a lifelong infection, most cats can live normal lives for many years after diagnosis with appropriate care. Prognosis depends on:

  • Age at time of infection – Younger cats typically progress more slowly.
  • Overall health – Cats who are otherwise healthy at diagnosis tend to live longest.
  • Presence of symptoms – Asymptomatic cats have better outcomes.
  • Supportive medical care – Veterinary monitoring and treatment greatly improve quality of life.
  • Stress level – Minimizing stress helps slow disease progression.

With early diagnosis and a low-stress indoor lifestyle, an FIV+ cat may never develop serious secondary symptoms and can live into their teens or older. However, without treatment, symptomatic FIV typically progresses to feline AIDS and ultimately proves fatal.

There is no need to euthanize a cat upon initial FIV diagnosis. With supportive care and veterinary oversight, FIV+ cats can enjoy many happy years as cherished family pets.

Key Takeaways on Feline Immunodeficiency Virus

  • FIV is a lentivirus causing progressive immune deficiency in domestic cats. It is also called feline AIDS.
  • It is transmitted primarily through serious bite wounds between cats. Casual contact does not spread FIV.
  • After initial flu-like symptoms resolve, infected cats enter an asymptomatic carrier state lasting years.
  • Eventually FIV destroys the cat’s immune system leading to chronic infections and illness.
  • Diagnosis is by a simple antibody blood test. Confirmatory testing may be needed.
  • There is no cure for FIV, but infected cats can live for many years with supportive medical care.
  • FIV is species-specific to felines. It poses no risk to human owners or other household pets.
  • FIV+ cats should be kept indoors and monitored closely by a veterinarian. With appropriate care, they can enjoy good quality of life.

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