Feline Infectious Peritonitis
Feline Infectious Peritonitis, FIP, is a disease of cats causing a variety of illnesses.
FIP is caused by a Coronavirus, so-called because under an electron microscope it looks like a crown or “corona.” There are a variety of coronaviruses that can infect cats and they range widely in virulence.
Sally, our totally indoor cat, contracted FIP through contact with a stray cat through our back porch screen.
At one end of the spectrum are coronaviruses which, while they can infect cats, don’t actually cause any disease. At the other extreme are coronaviruses so deadly that they can literally cause death in hours. Fortunately, these latter viruses are extremely rare.
Somewhere toward the left end of the range lies the Feline Infectious Peritonitis virus. In actuality, the virus itself is not bad at all. It is the body’s response to the virus that causes illness in cats.
FIP is most commonly transmitted by direct physical contact by cats sharing nasal and saliva droplets as they interact. The same particles may cause transmission via shared food or water bowls and litterboxes.
After infection, the virus replicates in the respiratory passages and pharynx. It spreads through the lymph system of the body, eventually having its greatest effect in the abdominal cavity and sometimes in the chest.
The end result is either the “wet” or “dry” form of Feline Infectious Peritonitis.
“Peritonitis” is a term indicating inflammation of the lining of the abdomen, peritoneum. The etymology of the word is fascinating. “Peri” is a prefix meaning around. “Teinen” means “to stretch.” Peritoneum is a membrane that is stretched over the surface of all of the abdominal organs.
If the immune system could simply leave well enough alone, the disease entity FIP would never develop. However, as the body reacts to the organism, granulomas develop.
In the “wet” form of FIP, fluid accumulates in the abdomen (and sometimes the chest cavity, also). Fluid collection can be so dramatic that affected cats become pot-bellied. If fluid builds up in the chest it can compress the lungs to the extent that breathing becomes difficult. Also, granulomas can invade lung tissue, resulting in further compromise of air exchange.
The dry form is similar, but without fluid gathering in the cavities.
Cats typically present as “poor do-ers.” They experience weight loss, decrease in appetite, poor hair coat and termination of self-grooming. Vomiting may occur if the intestinal tract is obstructed by granulomas. The physical examination is usually unrewarding, simply revealing the obvious.
Furthermore, routine laboratory tests are not much help. The chemistry profile may reveal abnormalities if granulomas have invaded the liver and/or kidneys, but such damage is not diagnostic of FIP. The CBC,
complete blood count, may show an elevation of white blood cells in response to the inflammatory process. Even so, that is a finding associated with hundreds of syndromes in addition to FIP.
For many years “the test” for FIP wasn’t much help, either, mainly because it wasn’t a test for FIP. Until recently it was nearly impossible to tell apart the body’s response to one coronavirus or another. Therefore, all we could say with a “positive” test was that your kitty had been exposed to and had responded to some coronavirus. Only in recent years have we had a test that was specific, and now your pet’s doctor can draw a blood sample, send it to a laboratory and know whether FIP is causing your cat’s illness.
Unfortunately, even with an accurate diagnosis we still have no effective treatment for Feline Infectious Peritonitis and the percentage of cats succumbing to the disease is in the high 90s. Symptomatic therapy can help make your kitty more comfortable, but nothing eliminates the infection and nothing totally stops the immune system’s self-destructive path. Even so, the course of the disease is often slow and cats may survive for many years.
A vaccine is available against FIP, but its use is controversial. Many experts believe that administration of the vaccine worsens the body’s response when/if natural disease exposure occurs. On the other hand, some practitioners trust it to reduce the incidence of the disease in multi-cat households and catteries.
Related posts:
- Infectious Canine Tracheobronchitis, Not Kennel Cough
- Feline Immunodeficiency Virus (FIV)
- Feline Leukemia Virus (FeLV)
