Feline Immunodeficiency Virus (FIV), often referred to as “Aids In Cats” or feline AIDS, is a globally prevalent and significant infectious disease affecting domestic cats. This virus targets the immune system, rendering infected cats susceptible to various secondary infections. While cats with FIV can appear healthy for extended periods, they eventually develop immunodeficiency. This weakened immune system allows opportunistic bacteria, viruses, protozoa, and fungi, commonly found in everyday environments, to trigger severe illnesses. Although there is no cure for FIV, recent research indicates that cats with FIV can often live average lifespans, especially if they are not co-infected with feline leukemia virus (FeLV).
Understanding the Risks and Transmission of FIV
The primary way FIV spreads is through deep bite wounds inflicted by an infected cat. Casual contact, such as sharing food and water bowls or mutual grooming, is not considered an efficient means of transmission. Therefore, cats living in stable, non-aggressive multi-cat households have a low risk of contracting FIV. Mother cats can, in rare instances, transmit FIV to their kittens, particularly if the mother becomes infected during pregnancy, which elevates the risk of transmission to the litter. Sexual contact is not a significant route of FIV transmission in cats.
FIV is found in cat populations worldwide, but the prevalence varies considerably geographically. In North America, approximately 2.5 to 5% of healthy cats are infected with FIV. This rate is significantly higher, reaching 15% or more, in cats that are already ill or considered at high risk of infection. Due to the bite wound transmission route, unneutered male cats who roam outdoors, particularly those prone to fighting, are at the highest risk for FIV infection. Currently, there is no commercially available vaccine in North America to protect against FIV. The most effective preventative measures include limiting contact with potentially infected cats by keeping cats indoors and ensuring all cats in a household are tested for FIV.
Clinical Signs of Feline AIDS: Recognizing the Stages of FIV
FIV infection in cats progresses through three distinct stages: the acute phase, the asymptomatic (or latent) phase, and the progressive phase.
The acute phase typically occurs one to three months post-infection. During this stage, the virus travels to the lymph nodes, where it replicates within T-lymphocytes, a type of white blood cell. The virus then disseminates to lymph nodes throughout the body, causing temporary lymph node enlargement, often accompanied by fever, lethargy, and loss of appetite. This initial phase can be mild and often goes unnoticed by cat owners or is mistaken for other common causes of fever.
Following the acute phase, cats enter the asymptomatic phase, which can last for months or even many years. During this latent period, the virus replicates very slowly within the immune system cells, and cats show no outward signs of illness. Bloodwork may reveal abnormalities, such as low white blood cell counts or elevated blood protein levels. Some cats may remain in this asymptomatic stage indefinitely and never progress to more severe disease.
As FIV continues to weaken the immune system, cats transition into the progressive immunocompromised state. This is when secondary infections become prevalent. Most illnesses associated with “aids in cats” are not directly caused by FIV itself, but rather by these opportunistic infections or immune system dysregulation. Cats may develop chronic or recurring infections affecting the skin, eyes, urinary tract, or upper respiratory tract. Gingivostomatitis, a severe inflammation of the gums and dental disease, is commonly seen in FIV-infected cats. They are also at a significantly higher risk of developing cancer and immune-mediated blood disorders compared to healthy cats. Other possible symptoms include weight loss, seizures, behavioral changes, and neurological disorders. The severity of these secondary illnesses varies greatly. However, once cats develop multiple severe infections or cancers, their survival time is typically limited to a few months.
Diagnosis of FIV in Cats: Antibody and PCR Testing
Determining a cat’s FIV status is crucial when they are first acquired, if they become ill, or if they are at risk of exposure. Regular testing is recommended for cats with potential exposure risks.
When a cat is infected with FIV, their immune system produces antibodies against the virus, which remain detectable in the blood for life. FIV diagnosis typically involves blood tests to detect these antibodies. The enzyme-linked immunosorbent assay (ELISA) test is commonly used and can be performed in veterinary clinics. Positive ELISA results are often confirmed with more specific tests like the Western blot or immunofluorescence assay (IFA) at a reference laboratory.
Because these tests detect antibodies, not the virus itself, there are situations where a single test might not definitively determine FIV infection status.
A negative antibody test usually indicates that the cat is not infected with FIV. However, there are exceptions. It takes 2 to 6 months for a cat to produce detectable antibody levels after infection. Therefore, a recently infected cat might test negative despite being infected. If recent exposure is suspected, retesting after at least 60 days is advisable for accurate results. In rare cases, cats in the late stages of FIV infection may test negative because their severely compromised immune systems no longer produce detectable antibodies.
Conversely, the presence of antibodies generally indicates FIV infection, as cats rarely clear the virus. However, false positives can occur. Confirmation with a secondary test is recommended for healthy cats with a positive ELISA result. Kittens born to FIV-infected mothers receive maternal antibodies, leading to positive test results for several months post-birth. Most of these kittens are not truly infected. Kittens under six months testing positive should be retested every 60 days until they are at least six months old to clarify their infection status. If the antibody test remains positive after six months, true infection is highly likely. FIV vaccines, previously available in some regions outside North America (like Australia, New Zealand, and Japan), also cause antibody production, leading to positive test results. Vaccination history is crucial for interpreting test results, though the absence of commercially available vaccines in North America since 2016 makes vaccine-induced positive results less common there.
To address some testing limitations, polymerase chain reaction (PCR) tests can detect viral genetic material directly. PCR tests identify the virus’s DNA rather than antibodies. While potentially useful as a confirmation test in some cases, PCR tests are not the preferred screening method due to higher rates of false positives and negatives.
Treatment and Management of Cats with AIDS
Currently, there is no definitive cure for FIV. However, it is important to emphasize that with appropriate management, cats infected with FIV can live long and healthy lives. Prognosis is less favorable once an FIV-positive cat has experienced severe illnesses related to the infection or presents with persistent fever and weight loss.
For healthy cats diagnosed with FIV, the primary management goals are minimizing the risk of secondary infections and preventing FIV transmission to other cats. Keeping FIV-positive cats indoors and separated from uninfected cats are crucial steps. Spaying or neutering prevents transmission through mating and reduces roaming and fighting behaviors if the cat gets outside. A nutritionally complete and balanced diet is essential. Raw food, such as uncooked meat and eggs, and unpasteurized dairy products should be avoided to minimize the risk of foodborne infections.
Regular veterinary wellness visits, at least every six months, are vital for FIV-infected cats. Veterinarians will conduct thorough physical examinations, paying close attention to gum, eye, skin, and lymph node health. Weight monitoring is crucial, as weight loss is often an early indicator of health decline. Annual complete blood counts, serum biochemical analyses, and urine analyses are recommended.
Vigilant monitoring of health and behavior is even more critical for FIV-positive cats compared to uninfected cats. Prompt veterinary evaluation and treatment are necessary at the first sign of illness, as most diseases in FIV-infected cats stem from secondary infections. These cats may require more prolonged or intensive treatments and antibiotic courses than non-FIV-infected cats. Antibiotics may be recommended prophylactically for routine procedures like dental cleaning or surgery to prevent secondary infections.
Direct antiviral treatment for FIV is limited and primarily involves drugs developed for human immunodeficiency virus (HIV). Zidovudine (AZT) can be helpful for cats with severe stomatitis or neurological disease, but it has not been shown to extend survival in FIV-infected cats and can have serious side effects. Ongoing research is exploring combination antiviral therapies for FIV treatment.
Prevention of FIV Infection in Cats
The only definitive way to protect cats from FIV is to prevent exposure to the virus. Since cat bites are the main transmission route, keeping cats indoors, away from potentially infected cats, significantly reduces the risk of infection. When introducing new cats to a household, ensuring they are FIV-free is ideal. In households with both FIV-positive and negative cats, separation is recommended if feasible. However, it’s important to remember that FIV transmission is less likely in stable multi-cat households where fighting is minimal.
FIV is fragile and does not survive long outside the host, typically only a few hours in most environments. However, FIV-infected cats may carry other infectious agents. Therefore, when introducing a new cat into an environment where an FIV-positive cat has lived, thorough cleaning and disinfection or replacement of food and water dishes, bedding, litter boxes, and toys is prudent to minimize the transmission risk of FIV and other infections. A diluted bleach solution (four ounces of bleach per gallon of water) is an effective disinfectant. Vacuuming carpets and mopping floors with a suitable cleanser are also recommended. New cats or kittens should be properly vaccinated against other feline infectious diseases before entering the household.
Human Health Concerns Regarding FIV
Although FIV is similar to Human Immunodeficiency Virus (HIV) and causes a disease in cats analogous to Acquired Immune Deficiency Syndrome (AIDS) in humans, FIV is highly species-specific and only infects felines. Currently, there is no evidence that FIV can infect or cause disease in humans. FIV poses no health risk to humans.
Last updated 2021
