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What is Feline Infectious Peritonitis?

Feline Infectious Peritonitis (FIP) is a viral disease that affects domestic and wild cats. It is caused by a type of coronavirus called feline coronavirus (FCoV). While many cats may be exposed to FCoV without showing symptoms, in some cases, the virus mutates and leads to the development of FIP. FIP can manifest in two forms: effusive (wet) or non-effusive (dry). Effusive FIP involves fluid accumulation in body cavities, while non-effusive FIP results in granuloma formation in various organs. FIP is a challenging disease to diagnose and manage, and unfortunately, it is often fatal. Treatment options are limited, and prevention efforts typically focus on minimizing exposure to the feline coronavirus. Regular veterinary check-ups, vaccination, and good hygiene practices can contribute to a cat’s overall health and reduce the risk of FIP.

What is FIP?

Feline infectious peritonitis (FIP) is a viral disease of cats caused by certain strains of a virus called the feline coronavirus. Most strains of feline coronavirus are found in the gastrointestinal tract and do not cause significant disease. These are referred to as feline enteric coronavirus (FeCV). Cats infected with FeCV usually do not show any symptoms during the initial viral infection, but may occasionally experience brief bouts of diarrhea and/or mild upper respiratory signs from which they recover spontaneously. FeCV-infected cats usually mount an immune response through which antibodies against the virus are produced within 7-10 days of infection.

In approximately 10 percent of cats infected with FeCV, one or more mutations of the virus can alter its biological behavior, resulting in white blood cells becoming infected with virus and spreading it throughout the cat’s body. When this occurs, the virus is referred to as the FIPV. An intense inflammatory reaction to FIPV occurs around vessels in the tissues where these infected cells locate, 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 therapy that has recently become available, but that has yet to be approved to treat FIP in cats by the Food and Drug Administration (FDA) (see below). To our knowledge, coronaviruses cannot be passed from infected cats to humans.

Symptoms of FIP

Cats that have been initially exposed to FeCV usually show no obvious symptoms. Some cats may show mild upper respiratory symptoms such as sneezing, watery eyes, and nasal discharge, while others may experience mild gastrointestinal signs such as diarrhea. In most cases, these mild signs are self-limiting. Only a small percentage of cats that are exposed to the FeCV develop FIP, and this can occur weeks, months, or even years after initial exposure to FeCV.

There are two major forms of FIP, an effusive, or “wet” form and a noneffusive, or “dry” form. Regardless of which form they ultimately progress to develop, cats infected with FIPV usually first develop nonspecific signs of 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 into the non-effusive form and vice-versa.

Generally speaking, the signs of the noneffusive form, which may include the non-specific signs listed above as well as neurologic signs including seizures and ataxia (abnormal or uncoordinated movements) develop more slowly than those of the effusive form.

The signs of effusive form of FIP usually develop and progress relatively rapidly and include development of the above-mentioned non-specific signs combined with the accumulation of fluid in body cavities, including the abdomen and the thorax (chest cavity). Affected cats may develop a pot-bellied appearance due to fluid accumulation in the abdomen, and if the fluid accumulation is excessive, it may become difficult for a cat to breathe normally.

Treatment and Prevention of FIP

Preventing Feline Infectious Peritonitis (FIP) is imperative for managing the spread of Feline Coronavirus (FCoV). In addition to fundamental practices such as good hygiene, stress reduction, and maintaining a healthy environment, there are specific preventive measures that cat owners can adopt. Isolating infected cats from healthy ones is crucial to prevent the transmission of the virus. Regular veterinary check-ups facilitate early detection, allowing timely intervention. Proper sanitation practices, including thorough cleaning and disinfection, minimize the persistence of FCoV in the environment, thereby reducing the risk of transmission. In multi-cat households, managing social dynamics and providing ample resources contribute to a harmonious environment, lowering stress levels known to exacerbate FIP. Additionally, staying informed about the latest research on FIP vaccines and consulting with veterinarians can guide cat owners in making informed vaccination decisions.

As for the treatment of FIP, it remains a complex and challenging aspect of feline healthcare. Supportive care plays a crucial role, encompassing proper nutrition, hydration maintenance, and addressing specific symptoms to enhance the overall well-being of the affected cat. Immunomodulatory therapy, despite being under investigation, aims to modulate the immune response to FCoV and may be considered in consultation with a veterinarian. Given the variable nature of FIP, close monitoring of the cat’s condition is essential, allowing veterinary professionals to adjust the treatment plan based on the cat’s response to therapy. In cases where a cure is not possible, palliative care becomes paramount, focusing on improving the quality of life for the cat through pain management and measures to ensure comfort. By incorporating these multifaceted approaches, both preventive and therapeutic, cat owners can better navigate the complexities of FIP management.