Everything You Need to Know About Feline Immunodeficiency Virus (FIV) in Cats
Feline immunodeficiency virus (FIV) is a disease that every cat owner should be aware of. It's especially important if you're thinking about bringing home a new feline friend. Testing new cats allows you to make informed decisions about adding the new cat to your household and the best care for that cat over the course of his life.
What Is Feline Immunodeficiency Virus (FIV)?
Feline immunodeficiency virus is a retrovirus that affects cats. According to the 2020 AAFP Feline Retrovirus Testing and Management Guidelines released by the American Association of Feline Practitioners (AAFP), FIV is present in cats around the world, affecting two to five percent of cats in North America.
How do cats get FIV? The vast majority of cats with FIV get it from being bitten by an infected cat. The virus takes up residence in the cat's lymph nodes and T-lymphocytes, spreading throughout the body. As the name suggests, the virus damages the cat's immune system and weakens it, making the cat susceptible to other infections and diseases.
Feline immunodeficiency virus works very similarly to human immunodeficiency virus. FIV itself will not kill your cat, but it does put him at increased risk for other conditions. It's these secondary infections and illnesses that cause the cat discomfort and will eventually lead to death. The chronic illness in end-stage FIV infections is sometimes referred to as feline AIDS.
Signs and Symptoms of FIV in Cats
Feline immunodeficiency virus symptoms vary depending on what secondary infection has taken advantage of the affected cat's weakened immune system.
Common symptoms of FIV in cats include:
Some cats may also show behavioral changes or other neurologic abnormalities, including seizures.
As you can see, there are no specific symptoms of FIV in cats that do not overlap with other conditions. Any cat with recurring infections that respond to treatment but then return should be suspected of having FIV, especially if he goes outside or has recently been bitten by another cat.
Testing Cats for FIV
Thankfully, testing for FIV can be done with a simple blood test. Many clinics and hospitals have in-house tests that test for both FIV and feline leukemia. Several different options are available, but the most common FIV test for cats is an enzyme-linked immunosorbent assay, or ELISA, which checks for antibodies to FIV present in the cat's blood.
When a cat is infected with FIV, his immune system will produce antibodies to combat the virus. These antibodies are what the tests check for. Adult cats who have not been exposed to FIV will not have antibodies.
No test is perfect, so if your cat does test positive for FIV, it is recommended to send out a blood sample for a second test to confirm the results. As well as antibody tests, it is also possible to do a polymerase chain reaction (PCR), which detects actual viral DNA present in the blood. The accuracy of PCR testing for FIV varies, so it's important to use a reliable lab.
It is possible to get a false negative result if the cat is tested too soon after infection. It typically takes eight to 12 weeks for antibody levels to become detectable. If your cat has been bitten by a cat who is known to be FIV-positive or whose status is unknown, it's important to retest your cat two months after the exposure occurred. False negative results can also occur in cats with extremely late-stage FIV because their immune systems have become so suppressed that they are no longer producing antibodies. These cats will show signs of illness.
Kittens can receive antibodies for FIV from their mother's colostrum if the mother is infected with FIV. After the kitten is weaned, these antibodies gained from maternal immunity will wear off and be cleared from the body by the age of six months. The AAFP recommends that any kitten who tests positive for FIV at a young age should be retested after turning six months old or have a PCR test done to confirm whether or not the kitten actually has FIV. It's rare for kittens to contract an FIV infection from their mothers.
So, which cats should be tested? The AAFP recommends testing all cats to establish their FIV status, especially before the cat is added to a new home or admitted to a shelter. This helps to prevent spread of the disease to other cats. Cats with persistent or recurring illness should also be tested to determine if FIV is an underlying factor. Cats who have previously tested negative and have been living indoors either alone or with other cats who they get along with are at low risk for contracting FIV and do not need to be retested unless a potential exposure occurs, such as slipping out a door and coming back with a bite wound.
Feline Immunodeficiency Virus Treatment
There is no treatment to cure FIV. The goal for infected cats is to keep them asymptomatic as long as possible and to treat secondary infections as they occur.
An asymptomatic cat that is FIV-positive should be kept indoors to limit exposure to parasites and diseases, as well as to prevent him from getting into fights and passing on the disease. These cats should also receive a balanced diet appropriate for their life stage. The AAFP recommends veterinary exams twice a year to catch any signs of illness early, as well as annual blood and urine tests. Even indoor cats should be kept on parasite preventive medications year-round.
The antiviral compound zidovudine (also known as azidothymidine or AZT) is sometimes used in FIV infections to reduce the viral load. The AAFP notes that it is particularly beneficial for cats who are showing neurological signs or have inflammation in the mouth.
FIV-positive cats who are showing signs of illness will receive supportive care, including fluid therapy for hydration and electrolyte replacement, anti-inflammatory medications, and immune-enhancing medications.
Tips for keeping your FIV-positive cat healthy include:
- Keep indoors
- Schedule veterinary exams every six months
- Have bloodwork and a urinalysis done each year
- Keep up to date on all vaccines
- Medicate for parasite prevention year-round
- Spay or neuter to decrease roaming and fighting behaviors as well as spread to kittens
- Monitor weight
- Feed a balanced diet
- Avoid raw foods due to increased risk of bacterial infection
RELATED: 10 Ways to Keep Your Cat Healthy
Is Feline Immunodeficiency Virus Contagious?
FIV only affects cats. It cannot be spread to humans or other animals. However, feline immunodeficiency virus is contagious from cat-to-cat. It is most commonly transmitted in the saliva, through a bite wound. Any cat can get it, but the cats most at risk for contracting FIV are intact male cats who roam and fight.
In rare cases, FIV can be transmitted from a mother cat to her kittens, usually before or shortly after birth. It can also be spread through infected blood, such as from a blood transfusion. It's unlikely to be spread through normal social interactions between cats, and it doesn't last long in the environment.
Vaccines for FIV have been made, but the one vaccine currently on the market is not available in the U.S. or Canada. Historically, FIV vaccines have not been 100% effective, meaning that vaccinated cats may still be at risk for contracting FIV. Vaccinated cats will also test positive on antibody tests. The AAFP does not consider this a core vaccine for cats, and does not recommend that cats receive it, but as always, vaccine decisions should be made on a case-by-case basis with your vet.
What's the Outlook? Life Expectancy for Cats With FIV
How long do cats live with FIV? The good news is that these cats can still live full, normal lives. The AAFP Retrovirus Guidelines state, "Studies demonstrate that retrovirus infected cats, especially FIV-infected cats, may experience normal longevity with appropriate husbandry and disease management."
FIV has three stages: acute, asymptomatic, and clinical. In the acute phase, generally one to three months after exposure, the cat may have enlarged lymph nodes and run a fever as the virus establishes itself. Some cats may also have a poor appetite during this time. Most cat owners never notice that anything is amiss.
As the cat develops antibodies to the virus, he enters the asymptomatic phase. This phase can last many years. The cat will appear healthy and normal, but can shed the virus in his saliva. Some cats may go through periods of illness, but then revert to apparent good health.
The clinical stage is when the immune system has declined to the point that the cat shows chronic signs of illness.
Because FIV-positive cats have a weakened immune system, they are at an increased risk for developing a wide range of infections and diseases. Even normally occurring bacteria can cause dangerous infections, and cats with FIV are five times more likely to develop cancer. Any sign of illness or infection in an FIV-positive cat should be addressed and treated promptly.
A cat does not need to be euthanized simply because he is positive for FIV. Good care and nutrition can keep him healthy for many years! As with any cat, euthanasia should be considered if illness is causing him to suffer.
Can FIV-Positive Cats Live With Other Cats?
Because FIV is a contagious disease, it is recommended to keep positive cats separate from negative cats. If you have an FIV-positive cat, adding a new cat can cause stress that makes him susceptible to illness (or the new cat could bring an illness in). If you have an FIV-negative cat and are considering adopting an FIV-positive cat, introductions must be done very slowly and cautiously to avoid fighting and exposing your original cat. If one of your current cats tests positive, all cats in the household should be tested and then ideally separated into groups to prevent infection of the healthy cats.