What is Feline Infectious Peritonitis?
Feline infectious peritonitis (FIP) is a syndrome that results from wide-spread infiltration of the body’s organs with a type of inflammatory tissue called pyogranuloma. The resulting inflammation leads to organ failure, uncontrollable fevers and sometimes an accumulation of thick yellow fluid in the belly or chest (referred to as the wet form of FIP). This is unfortunately rapidly fatal. The “dry” form of FIP is slower to reveal itself and may cause issues over months to years. Both forms have 100% mortality.
FIP is a reaction to a Feline Enteric Coronavirus infection. Many cats that develop Feline Coronavirus will never have this reaction and often it goes unnoticed.
What do we know about the Feline Enteric Coronavirus?
- It is common wherever cats are housed in groups and it is readily transmitted between cats.
- Transmission is typically by contact with infected faeces. The virus enters the new host’s body via the nose and mouth.
- An active infection lasts several weeks to a few months. Virus is shed in the infected cat’s stool during this period. If the cat is reinfected, virus sheds again for weeks to months. During this time, the cat may or may not seem at all ill. Some infected cats do not shed virus.
- Most household disinfectants readily kill coronavirus immediately. Room temperature kills coronavirus within 48 hours. Carpeting is protective to the virus and the virus is able to survive in carpeting for at least 7 weeks.
- Once a cat has been infected with the virus and recovered, the cat can be easily re-infected by continued exposure to infected faeces. In this way, many catteries where there are always cats sharing litter boxes never rid themselves of this infection.
- The enteric coronavirus attacks intestinal cells and creates gastrointestinal (GI) upset. As long as the infection is confined to the GI tract, there will be no FIP.
How Coronavirus changes to FIP
This involves an inflammatory cell called a macrophage. In most cases the macrophage cells kill the virus but in some cases Coronavirus mutates and survives the macrophage attack. The virus then uses these cells to move around the body and as more macrophages are produced in an attempt to respond to the virus pyogranulomas are formed.
This mutation is mostly likely to occur in immune-compromised cats e.g. young cats (under 1 year old) or those in an overcrowding situation (e.g. shelter cats).
Why isn’t the mutated virus contagious?
We do not know why. We do know FIP cats shed Coronavirus but are NOT CONTAGIOUS.
Whilst we can test for active Coronavirus, there is no test for the mutated version i.e. FIP. Because of this diagnosis is based on clinical symptoms, fluid testing and blood results including:
- Elevations in total protein and gamma globulins on blood work.
- Reduced albumin (protein) levels on blood work.
- Testing the fluid accumulation in the belly or chest (basic cell evaluation and Immunoflurorescent Coronavirus staining).
- Occasionally biopsy of affected tissue is considered.
There is no effective treatment for FIP and it unfortunately has virtually 100% mortality (death). The goal of confirming FIP (as best as can be done) is to rule out other diseases. Treatment is offered in the form of palliation to alleviate symptoms where possible. It is important to realize that since this is a progressive disease owners should prepare themselves for the decision to euthanase.
There are a few experimental treatments currently being explored:
FIP is a disease created by the cat’s own immune system. Immunosuppressive drugs such as prednisone and cyclophosphamide have been used to slow the progression of FIP.
Removing the effusion
Suctioning of the effusion will ease the difficult breathing of a cat with fluid in its chest, but even removing the effusion from the belly helps remove a large source of inflammation. Some cats experience a temporary improvement with the fluid removed.
Interferon gamma is being investigated.
When a cat dies of FIP what is the infection risk to the remaining cat?
If an FIP infected cat is housed with other cats they will be infected with Coronavirus. Whilst these cats are at no higher risk of contracting FIP than any other cat, if they are a litter mate they might be slightly predisposed due to genetic factors.
When is it safe to get another cat?
We recommend waiting 3 months before getting another cat. If there are other cats in the household we recommend testing FIP titres every 3 months and only introducing a new cat once these are negative. It is also advised to test the new cat for FIP titres.
Is there a vaccination?
There is only one vaccine that has been developed against FIP and its effectiveness remains questionable. For this reason we do not recommend vaccination.
Is Infection Limited to Cats?
Yes. Dogs and humans cannot get sick from feline coronavirus. The feline coronavirus is not involved in SARS (severe acute respiratory syndrome) although SARS is caused by a coronavirus.