What is FIP?
Feline infectious peritonitis (FIP) is a viral disease of cats caused by certain strains of a virus called feline coronavirus. Most strains of feline coronavirus are found in the gastrointestinal tract and do not cause significant illness. These are known as feline enteric coronavirus (FeCV). FeCV-infected cats generally do not show any symptoms during the initial viral infection, but may occasionally experience brief episodes of diarrhoea and/or mild upper respiratory symptoms from which they recover spontaneously.
FeCV-infected cats typically mount an immune response whereby antibodies against the virus are produced within 7 to 10 days of infection. In about 10 per cent of cats infected with FCV, one or more mutations in the virus can alter their biological behaviour, causing white blood cells to become infected with the virus and spread it throughout the cat’s body. When this happens, the virus is called FIPV.
A strong inflammatory reaction to FIPV occurs around the vessels in the tissues where these infected cells are located, often in the abdomen, kidney, or brain. It is this interaction between the body’s own immune system and the virus that is responsible for the development of FIP. Once a cat develops clinical FIP, the disease is usually progressive and almost always fatal without newly available therapy, but not yet approved to treat FIP in cats by the Food and Drug Administration (FDA) (see more down). To the best of our knowledge, coronaviruses cannot be transmitted from infected cats to humans.
What are the symptoms of FIP?
Cats that have been initially exposed to FeCV do not usually show overt symptoms. Some cats may display mild upper respiratory symptoms such as sneezing, watery eyes, and runny nose, while others may experience mild gastrointestinal symptoms such as diarrhoea. In most cases, these mild signs are self-limiting. Only a small percentage of cats that are exposed to FeCV develop FIP, and this can occur weeks, months, or even years after the initial exposure to FCV.
There are two main forms of FIP, an effusive or “wet” form and a non-effusive or “dry” form. Regardless of which way they eventually progress to develop, cats infected with FIPV usually first develop nonspecific signs of the disease, such as loss of appetite, weight loss, depression, and fever. It is also important to note that cases of the effusive form of FIP can evolve to the non-effusive form and vice versa.
Generally speaking, signs of the non-effusive form, which may include the non-specific signs listed above, as well as neurological signs including seizures and ataxia (abnormal or uncoordinated movements), develop more slowly than those of the effusive form.
Signs of the effusive form of FIP usually develop and progress relatively quickly and include the development of the non-specific signs mentioned above combined with the accumulation of fluid in body cavities, including the abdomen and thorax (thoracic cavity). Affected cats may develop a pot-bellied appearance due to fluid buildup in the abdomen, and if the fluid buildup is excessive, it can make it difficult for the cat to breathe normally.
Can FIP be treated?
Until recently, FIP was considered a non-treatable disease. While some uncertainties remain regarding the long-term effectiveness of newly identified antiviral medications for treating FIP (most importantly regarding their effectiveness in treating the non-effusive form of FIP), studies in both the laboratory as well as in client-owned cats with naturally occurring FIP suggest that a drug currently named GS-441524 may ultimately prove to be an effective treatment option for (minimally) the effusive form of FIP.
Although some cases of the non-effusive form of FIP did respond to GS-441524 therapy in these trials, the responses in cases with this form of FIP were not as favourable as those seen in cases of the effusive form. However, this drug is not currently FDA-approved, and while there are several sources offering it for sale, anecdotal reports suggest that the products provided by some of these sources vary widely in both concentration precision and safety. reported drug purity.
It is very important to discuss the risks, benefits, and evolving regulatory and procurement issues with your veterinarian if you are considering therapy with GS-441524. In some cases, supportive care, including fluid therapy, drainage of accumulated fluids, and blood transfusions, is also indicated.