Feline infectious peritonitis (FIP) may sound like an odd name for a virus, especially when infection doesn’t always cause peritonitis (inflammation of the lining of the abdomen). But FIP is nothing to dismiss. Infection with this virus can cause appetite loss, fever, vomiting, diarrhea, seizures, and death. A vaccine against FIP is available, but it’s not part of the routinely recommended vaccines for most cats.

Overview

Feline infectious peritonitis (FIP), which is caused by a contagious virus, can cause significant illness and death in cats. Despite the name of this disease, it does not always cause peritonitis (inflammation of the lining of the abdomen), but this complication happens in a large percentage of infected cats. Once a cat is infected, the virus can spread through the entire body. Complications depend on the type of illness the disease causes and which areas of the body are involved.

The FIP virus is transmitted through exposure to feces from an infected cat. Kittens can become infected shortly after birth if their mother was already infected. Cats in communal living conditions, such as some breeding facilities, catteries, and shelters, are at increased risk for exposure. The FIP virus can live for several weeks on contaminated litterboxes, food bowls, and water bowls. However, the virus is killed by bleach, so cleaning contaminated areas with a dilute bleach solution can decrease the risk of disease spread.

Some cats can become carriers of FIP. This means that after they become infected, they don’t develop clinical signs of disease but can be a source of infection for other cats.

Symptoms and Identification

There are two forms of FIP, and the clinical signs of the disease can depend on which form an infected cat develops. With “wet” FIP, infected cats develop fluid accumulation in certain areas of the body — most commonly in the abdomen or chest cavity, and the amount of fluid can be large enough to cause discomfort and trouble breathing. The “dry” form of the disease occurs when cats develop nodules (lumps) on certain organs in the body. These nodules are not tumors but are the body’s response to the infection and inflammation caused by FIP. Nodules can occur in many places, including the liver, lungs, spleen, and brain. Clinical signs of FIP can include the following:

  • Pain or swelling of the abdomen (wet form)
  • Weight loss (both forms)
  • Lethargy/tiredness (both forms)
  • Appetite loss (both forms)
  • Seizures and paralysis (dry form)
  • Inflammation of the eyes (dry form)
  • Vomiting, diarrhea, constipation (dry form)

Depending on the form of illness (“wet” or “dry”), FIP may be difficult to diagnose. Diagnosing the “wet” form can be fairly straightforward. Your veterinarian can remove a small sample of fluid from your cat’s abdomen or chest cavity and analyze the fluid for characteristics associated with FIP. Diagnosing the “dry” form can be more complicated. Blood testing can raise your veterinarian’s level of suspicion but cannot be used to reliably diagnose the disease in many cases. This is because specific blood tests that detect the FIP virus cannot reliably tell the difference between FIP and other similar viruses. Your veterinarian may recommend additional blood testing, such as a chemistry panel and complete blood cell count (CBC), to check for changes consistent with FIP. Diagnosis is sometimes based on an accumulation of supportive evidence rather than a single test.

Treatment

No drug can eliminate the FIP virus, and no reliable treatment for FIP is available. Medications may temporarily help with clinical signs, but most cats that develop clinical signs eventually die of associated complications.

Vaccine Characteristics

The American Association of Feline Practitioners has grouped vaccines for cats into three general categories – “core” (all cats should receive the vaccine), “non-core” (recommendation is based on risk for exposure to the disease), and “not generally recommended” (have little or no indication). The FIP vaccine has been included in this third category. Categorization as “not generally recommended” does not mean the vaccine is bad or dangerous – it simply means that widespread use is not generally recommended among pet cats. If the FIP vaccine is used, antibody testing before vaccination is advised, since cats that have already been exposed and have antibodies don’t benefit from vaccination.

Delivery

This vaccine is administered intranasally (as nose drops).

Recommended Schedule

While your veterinarian is always in the best position to advise you on individual vaccination decisions and schedules, according to the American Association of Feline Practitioners’ 2006 vaccination guidelines, the FIP vaccine can be given according to the following schedule:

  • If administered, give a single dose as early as 16 weeks of age, and a second dose three to four weeks later. 
  • If initially administered to adult cats or kittens older than 16 weeks of age, give two doses three to four weeks apart.
  • An annual booster is recommended by the manufacturer.

Cats that live with other cats or are routinely exposed to other cats are at greater risk for exposure to FIP compared with cats in single-cat households that have limited or no contact with other cats. If your cat’s risk for exposure is low, your veterinarian may not recommend the FIP vaccine. Ask your veterinarian about how to protect your cat from this disease.

Precautions

Administering a vaccine is a medical procedure, and there are times when a vaccine may not be recommended. For example, your veterinarian may advise against vaccinating an animal that is currently sick, pregnant, or may not have adequate immune system functioning to respond to a vaccination. For pets with a previous history of vaccine reactions, the potential risk of a future vaccine reaction should be weighed against the potential benefits of vaccination. These and other issues are evaluated when deciding what is best for your pet.

Alternatives

There is no known alternative to FIP vaccination. However, preventing overcrowding, keeping cats current on recommended vaccinations, and providing proper nutrition will help decrease the spread of many infectious diseases.

Because FIP is transmitted through contact and fecal material, keeping sick cats separated from healthy cats can reduce the likelihood of transmission. The FIP virus is killed by bleach, so litterboxes and food/water bowls can be cleaned with a dilute bleach solution.

Any new kitten or cat being introduced into the home should be examined by a veterinarian as soon as possible and separated from all other household pets for a quarantine period. During that time, the new cat should be monitored closely for any signs of illness. Any problems should be reported to your veterinarian before introducing the new cat to your other pets.

References

American Association of Feline Practitioners’ vaccination guidelines 

Cornell University College of Veterinary Medicine

This article has been reviewed by a Veterinarian.