Clinical Signs of Feline Infectious Peritonitis (FIP)

Feline infectious peritonitis is a viral disease that affects many of your cat's body systems. The disease is progressive and usually fatal. Feline FIP affects wild cats, such as cougars, lynx, bobcats and lions, as well as domestic cats and is found worldwide.

Incidence and Transmission of FIP in Cats

Studies show that 25-40% of house cats are or have been infect with feline cornavirus (FCoV), the virus that causes feline infectious peritonitis. Fatal FIP strikes 1 in 5000 house cats.

FCoV can be found in the saliva and excrement of infected cats. The most common modes of transmission are cat-to-cat contact and exposure to the feces of infected cats. Food and water dishes, bedding, and personal belongings can also spread the disease. FCoV can live outside the host for three to seven weeks. Disinfectants will kill FCoV, including a solution of bleach diluted 1:32 in water.

How Feline Coronavirus Causes Feline Infectious Peritonitis

When a cat is exposed to FCoV, one of four things can happen:

  • The cat's immune system can fight off the infection. This occurs in healthy cats with strong immune responses.
  • The cat's immune system may not be able to kill off the virus entirely, but can keep it in check. This causes what is known as a "latent" infection. If the cat's immune system is compromised by stress or another illness, it can develop FIP.
  • If the cat's immune system is somewhat weak, the virus multiplies slowly, and FIP develops. This form of the disease is known as "dry" feline infectious peritonitis, and causes nodular lesions or grandulomas to develop in one or more places on the body.
  • If the immune system is very weak, the virus replicates quickly and "wet" FIP develops. In this form of the disease, damaged blood vessels cause fluid to build up in the chest and abdominal cavities.

Symptoms of Feline Infectious Peritonitis

FIP in cats occurs in two forms, noneffusive (or dry) and effusive (or wet). Dry FIP occurs in about one quarter of cats infected with FIP. Symptoms of the dry form usually come on more slowly. They include such nonspecific signs as:

  • Chronic weight loss
  • Fever
  • Lack of appetite
  • Lethargy

Other signs of dry FIP depend on which organs are damaged by the appearance of granulomas within the body. Ten to twenty-five percent of cats will develop granulomas in the central nervous system, resulting in neurological symptoms such as:

  • Paralysis
  • Disorientation
  • Loss of balance
  • Tremors
  • Convulsions
  • Behavior changes
  • Urinary incontinence

Sometimes the liver or kidneys are affected; usually chemistry tests are needed to reveal the affects of granulomas in these organs. Granulomas in the eye may cause the pupil to appear irregular and the eye to appear discolored. Cats with dry FIP may live up to a year after symptoms appear.

The early symptoms of wet or effusive feline infectious peritonitis are the same as the early symptoms of the noneffusive form. As the disease progresses, anemia, constipation and diarrhea may occur. The effusive form of FIP progresses rapidly and the cat may take on a pot-bellied appearance as fluids build up in his abdomen. Respiratory difficulties may occur as fluid builds up in the cat's chest; cats with effusive FIP usually die within two months of showing symptoms.