Should Fluffy Get the FIV Jab? Weighing the Pros and Cons of Feline Vaccination

What is FIV?

Feline immunodeficiency virus (FIV) is a retrovirus that affects cats. It weakens the immune system and makes cats more susceptible to other infections and diseases. FIV is sometimes referred to as the feline equivalent of HIV in humans, although there are some important differences.

FIV is primarily transmitted through deep bite wounds, where the virus present in an infected cat’s saliva enters the bloodstream of another cat. Cat bites are by far the most common route of spreading FIV. Less common means of transmission include from mother to kitten in utero or through milk, blood transfusions, and shared food/water bowls and litter boxes.

FIV is considered relatively rare compared to other feline viruses. According to Cornell University’s College of Veterinary Medicine, prevalence rates range from 1-14% globally, with an average of 2-3% of cats infected [1]. However, rates are higher in cats that are outdoors and engage in risky behavior like fighting.

Symptoms of FIV

Cats infected with FIV may show no signs initially. Early symptoms can be mild and nonspecific, including fever, loss of appetite, and lethargy. Within a few weeks of infection, there may be enlargement of the lymph nodes, persistent fever, and inflammation of the gums.

As FIV progresses, cats experience more severe symptoms. Years after the initial infection, cats develop chronic disorders due to a weakened immune system. These include infections affecting the mouth, skin, urinary tract, and respiratory system. Other late-stage symptoms include dental disease, kidney failure, cancer, and neurological problems like behavior changes and seizures.

Without treatment, FIV leads to a compromised immune system that struggles to fight off other infections. FIV itself is not fatal, but it increases susceptibility to a variety of secondary diseases that can shorten lifespan or deteriorate quality of life.

Testing for FIV

It’s recommended to test kittens for FIV before adopting them, especially if they came from unknown origins like a shelter or the street. Annual testing is also advised for adult outdoor cats at high risk of exposure. If a cat is showing potential symptoms of FIV like chronic illnesses, getting them tested can help identify the cause.

There are different types of FIV tests available. The most common is the ELISA test, which detects antibodies to the virus in the blood ( Another option is the PCR test, which detects the virus’s genetic material directly. The ELISA test is affordable and widely available, while PCR is more accurate but pricier.

The accuracy of FIV tests depends on the age of the cat. Maternal antibodies in kittens under 6 months can cause false positives, so kittens should be retested after 6 months for confirmation. Otherwise, the ELISA and PCR tests are highly accurate when performed properly on adult cats.

Transmission of FIV

FIV is primarily transmitted between cats through deep bite wounds. The virus is shed in high quantities in the saliva of infected cats, so a bite that breaks the skin and draws blood allows the virus to enter the body of an uninfected cat (1). Casual contact such as sharing food bowls or grooming is unlikely to lead to transmission. The main risk factors for a cat acquiring FIV are:

  • Free-roaming outdoor cats – Access to other cats increases fighting risk
  • Adult male cats – More territorial and prone to fighting
  • Multi-cat households with cats from different sources/backgrounds – Higher likelihood of having an infected cat

Kittens can also contract FIV while nursing from an infected mother cat, but this risk is significantly reduced if kittens are weaned by 4 weeks of age (2).


Treatment of FIV

There is currently no cure for FIV. Treatment focuses on supportive care and keeping the cat as healthy as possible (Cornell). Since FIV suppresses the immune system,infected cats are more prone to secondary infections. Veterinarians will monitor the cat closely and treat any secondary infections with antibiotics or other medications as needed. Providing good nutrition, minimizing stress, and keeping vaccinations up to date are all important parts of supportive care for FIV positive cats (WebMD). While there is no cure, with diligent supportive care and monitoring, many FIV positive cats can live long and relatively healthy lives.

Prevention of FIV

There are several ways cat owners can help prevent the spread of FIV:

Keep cats indoors. Since FIV is usually spread through bite wounds from fighting, keeping your cat indoors eliminates the risk of exposure from infected stray or outdoor cats. Indoor cats live longer, healthier lives in general.

Limit exposure to infected cats. Do not allow your FIV-negative cat to interact or share food/water bowls with any cats that are positive for FIV. This helps stop the spread of the virus.

Early spay/neuter. Spaying or neutering your cat before 6 months of age greatly reduces the likelihood of your cat roaming, fighting with other cats, and contracting FIV. It also has long-term health benefits.

These steps are the most reliable ways to protect your cat from contracting FIV. Since there is no cure, prevention is key. Consult with your veterinarian about the risks in your area and the best prevention plan for your cat.

Vaccinating Against FIV

There are currently two FIV vaccines approved for use in cats – Fel-O-Guard III and Fel-O-Vax FIV. These vaccines help reduce the risk of FIV infection, but do not provide 100% protection.

According to studies, the Fel-O-Guard III vaccine has an efficacy rate of around 78% when challenged with FIV infected cats. The Fel-O-Vax FIV vaccine has shown similar results in trials, with efficacy rates ranging from 60-100% depending on the challenge virus strain used (source:

Potential side effects of the FIV vaccines include mild inflammation at the injection site and possibly a transient increase in body temperature. More severe reactions are rare but can include facial edema, vomiting, diarrhea, or lethargy. Most cats tolerate the vaccines well with minimal side effects (source:

Cost of FIV Vaccine

The cost of the FIV vaccine can range from $25 to $45 per dose depending on the veterinarian clinic and geographic location. Most cats require an initial vaccination series consisting of two doses administered 2-4 weeks apart, followed by an annual booster vaccination. Therefore, the total cost for the initial FIV vaccine series can range from $50 to $90.

In addition to the cost of the vaccine itself, there are costs associated with the veterinary office visit to administer the vaccine. A routine annual exam typically costs $50 to $100. Some clinics offer a lower-cost vaccine visit without an exam for established patients, which may range from $20 to $40. Location and individual clinic pricing can affect these costs.

Pet owners should factor in the exam fees each time their cat needs to be brought to the veterinarian for vaccines. The initial FIV vaccine series will require a minimum of two vet visits, and annual boosters will require one visit per year over the lifespan of the cat.

Some sources for FIV vaccine pricing information include:

Decision Factors

There are several lifestyle factors pet owners should consider when deciding whether or not to vaccinate their cat against FIV:

If your cat goes outdoors unsupervised or has exposure to stray/untested cats, their risk level for contracting FIV may be higher, so vaccination may be recommended. Indoor cats have a much lower risk of exposure. According to one source, “FIV is relatively difficult to transmit. Adult cats can live with FIV cats for years without contracting the virus themselves” (

It’s important to consult your veterinarian, as they can assess your cat’s specific risk factors and recommend whether vaccination makes sense. The FIV vaccine requires an initial series of 3 doses, so it’s not a small commitment. Vets can provide guidance based on your cat’s age, health status, lifestyle, and potential for exposure.

In general, the FIV vaccine is considered non-core, so it’s not necessarily recommended for every cat. But for higher risk cats, vets may advise vaccination as a preventative measure.


Should you vaccinate your cat against FIV? After reviewing the key points, the recommendation is that vaccination is likely worth considering for most cat owners.

FIV is a serious disease that weakens a cat’s immune system and can lead to chronic illness or cancer. It spreads through deep bite wounds, mainly from outdoor territorial fights. There is no cure, so prevention is key.

The FIV vaccine available for cats provides reasonable protection against infection. It requires an initial set of two doses, with an annual booster. Side effects are rare and mild. Cost is around $20-40 per dose.

Vaccination is especially advised for cats going outdoors and those with exposure to unfamiliar cats. Indoor cats can be at risk too if they ever escape or get in fights. The vaccine reduces but does not eliminate the risk of FIV infection.

Overall, the benefits of protection from this serious disease appear to outweigh the low risks and costs of vaccination for most cat owners. Talk to your veterinarian about whether vaccinating against FIV is recommended for your cat.

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