Feline infectious peritonitis (FIP) is a progressive and ultimately fatal disease of cats caused by a mutated coronavirus.
Many cats are infected with a relatively benign form of the coronavirus but only in certain cats will the virus mutate to become pathologic (FIP). So this means that the corona virus in each individual cat can mutate (or not) into the FIP virus. Therefore, FIP is not horizontally transmitted (cat to cat).
Previously, it was suggested that cats could transmit the disease to other cats by saliva, urine, and feces. It was also suggested that multi-cat households may increase the risk of disease. Recently, research has suggested that risk of virus transmission from an infected cat to other cats in the household very unlikely. Cats living with an FIP cat will be no more likely to have this mutation in the future than they otherwise would have been not being exposed to the FIP cat.
Contact with feces is a possible route of infection. However, once the virus is mutated, pathogenic coronavirus invades and is no longer shed from the gut.
Factors that increase the risk of infection include young age and concurrent infection with feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV).
The two forms of lethal FIP are effusive (wet) FIP, non-effusive (dry) FIP and combinations of both. Effusive FIP. The most characteristic sign is the accumulation of fluid within the abdomen or chest. Excessive accumulation may cause difficulty in breathing.
Non-effusive FIP. The onset is usually slower. Fluid accumulation is minimal, although weight loss, depression, anemia and fever are almost always present. You might also see signs of kidney failure, liver failure, pancreatic disease and other diseases. It is often a difficult disease to diagnose because signs are similar to other diseases.
Although the virus can survive for a number of weeks in the environment, it is inactivated by most household detergents and disinfectants.
What to Watch For
Symptoms of FIP are non-specific but may include any of the following:
Loss of appetite
Jaundice (yellow color of the skin, eyes, ears, nose or gums)
Distended abdomen (in effusive FIP)
Difficulty breathing (from fluid accumulation in the chest)
Seizures or paralysis with nervous system involvement
There are no specific tests to diagnose FIP. Your veterinarian will take a complete medical history and perform a thorough physical examination to facilitate diagnosis. Most cats presented for veterinary attention already are sick and several other diseases produce similar symptoms. Consequently, your veterinarian likely will recommend certain tests to rule out diseases other than FIP. These tests may include the following:
Thorough eye examination, including funduscopic examination to evaluate the back of the eyes, to evaluate for abnormalities characteristic of FIP
Complete blood count (CBC or hemogram) to evaluate for low lymphocyte count and anemia (abnormalities often seen in cats with FIP)
Serum biochemistry tests to evaluate the effect of FIP on organs such as the kidney and liver and to evaluate the general health of your cat. This test can also determine blood protein levels. High levels can help indicate FIP infection.
Feline leukemia virus (FeLV) test and feline immunodeficiency virus (FIV) test to evaluate your cat for other serious viral infections
FIP titer (serum antibody test). It is important to note that this test identifies the presence of antibodies against coronavirus but cannot determine with certainty that the antibodies are specifically against the coronavirus that causes FIP. A specialized molecular diagnostic test called polymerase chain reaction (PCR) recently has become available for the diagnosis of FIP but requires more widespread testing to determine its usefulness.
Microscopic analysis of fluid taken from the chest or abdomen
Urinalysis to evaluate kidney function
X-rays of the chest to identify fluid accumulation
X-rays of the abdomen to identify organ enlargement (e.g., liver, kidney)
Abdominal ultrasound examination to identify organ enlargement and infiltration of organs with masses that could represent inflammatory infiltrates called granulomas that are typical of FIP
Microscopic and chemical analysis of cerebrospinal (CSF) fluid in cats with nervous system symptoms compatible with FIP
There is no definitive treatment or cure for FIP, and treatment is limited to supportive and symptomatic care. Depending on the severity of your cat's illness, treatment may vary from outpatient care to hospitalization and intensive fluid and drug treatments. Treatment may involve one or more of the following:
Administration of fluids intravenously or subcutaneously (i.e. under the skin) to correct dehydration
Administration of anti-inflammatory cortisone-like drugs called glucocorticoids such as prednisone
Administration of broad spectrum antibiotics to combat secondary bacterial infection
Administration of drugs such as cyclophosphamide, melphalan or chlorambucil to suppress the immune system, which contributes to the severity of inflammation in cats with FIP
Administration of human interferon-alpha (Roferon). This drug is considered controversial in the treatment of FIP
Administration of anti-inflammatory and anti-coagulant drugs such as aspirin. Aspirin must only be given every second or third day to cats because cats normally are slow to metabolize aspirin
Administration of multiple vitamin supplements
Thoracocentesis, which is removal of fluid from the chest cavity with a needle, to make breathing less difficult in cats with fluid accumulation in the chest cavity
Supplemental oxygen administration in cats with fluid accumulation in the chest cavity
Nutritional support by tube feeding special products via the nasogastric tube – a small tube passed through the nose into the esophagus and stomach – or gastrostomy, which is a larger tube placed into the stomach through the skin with the aid of an endoscope.
Home Care and Prevention
At home administer as directed any medication prescribed by your veterinarian and encourage your pet to eat and drink.
A vaccine is available to help reduce the risk of contracting FIP. However, recently the vaccine has fallen out of favor and is not commonly used or recommended. A recent study suggested that the vaccine has not proven to be especially effective.
Keep food away from litter boxes to prevent fecal contamination and potential coronavirus transmission and clean litter boxes regularly to avoid transmission of coronavirus shed in feces.