Feline Infectious Peritonitis Virus can Remain Dormant for Years

Feline Infectious Peritonitis (FIP) is a serious viral disease that affects only cats, especially young cats and older cats. The virus can cause disease within two weeks after exposure but it can also remain dormant in some cats for months and even years before disease occurs.

Because various body systems can be affected, clinical signs of FIP can be quite variable and often misleading. Non-specific signs may include fever, gradual loss of appetite, and weight loss that lasts for several weeks. Clinical signs often reflect which part of the body is affected. For example, if the eyes are affected, blindness may occur, while seizures may occur if the brain is affected.

There are two kinds of FIP: the wet form and the dry form. The wet form results in an accumulation of fluid in the chest, leading to breathing difficulties, or in the abdomen, causing a large, bloated appearance. The dry form affects the same parts of the body as the wet form but no fluid is produced. The dry form may eventually progress to the wet form if the patient lives long enough.

Cats with FIP are infectious to other cats during the initial two to four week period immediately following infection. It is at this time that large numbers of viruses are shed. After this stage, the virus becomes inactive within the cat and the cat does not show any signs of disease. This stage may last for several months or even years. If during this time the cat becomes stressed in any way, virus shedding may occur and any cat exposed may get the disease. Eventually, however, the patient becomes clinically ill. This final stage lasts only a few weeks and usually ends in death. Recovery is extremely rare.

Diagnosing FIP can be both difficult and frustrating since there are no specific tests that are completely reliable. Diagnosis is often based on a combination of blood tests, fluid analysis,
x-rays and biopsies. There is also no effective treatment available and euthanasia is usually recommended.

Even though a vaccine against FIP is available, most veterinarians do not recommend routine vaccination against FIP. Vaccination is, however, recommended for cats that routinely go outdoors and come in contact with other free-roaming cats. It is also recommended for cats that come from households that have had a cat with FIP. If in doubt about vaccinations, ask your veterinarian for advice.