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An In-depth explanation of Feline Infectious Peritonitis (FIP)

What is FIP
FIP, or feline infectious peritonitis, is a serious and often fatal disease in cats that stems from a mutation of a common virus found in their intestines, known as the feline coronavirus. Normally, this virus doesn't cause any serious issues, but when it mutates, it can attack the cat's immune system and lead to severe health problems.


What triggers this mutation isn't fully understood, but it often happens when a cat's immune system is weakened—due to stress, being neutered, or living in poor conditions. Once the virus mutates, it can lead to feline infectious peritonitis.


There are two main types of FIP: wet FIP and dry FIP. Both types are linked to problems with the immune system and are more likely to develop in cats that are very young, very old, or have weakened immune systems. Symptoms of FIP can vary, but they often include issues like weight loss, lethargy, and in more severe cases, fluid accumulation in the abdomen or chest.


Wet FIP (Feline Infectious Peritonitis), the more common form of feline infectious peritonitis, is a severe condition in cats where fluid accumulates in the abdomen and chest, often noticeable as a swollen belly. This fluid is typically yellow and sticky, causing a drop in body temperature. The disease mainly affects young kittens or older cats, particularly those with weakened immune systems. 


Wet FIP occurs when a cat's immune system fails to combat the virus effectively, allowing it to spread and cause widespread inflammation. This form of FIP can be identified more easily than others due to the visible swelling caused by fluid buildup. The quick diagnosis of wet FIP can lead to more effective treatment options, like GS-441524, improving the chances of survival compared to other forms of the disease.

To enhance the information about Wet FIP in cats, you can include details about the signs and progression of the disease, as well as other treatment options and preventative measures. Here's how you could expand the description:

Wet FIP is particularly aggressive due to the rapid accumulation of fluid, leading to pressure on the organs and discomfort or pain for the cat. Beyond the visible symptoms like swelling in the abdomen, cats may also exhibit decreased appetite, weight loss, fever, lethargy, and difficulty breathing due to the fluid in the chest.

Regarding treatment, GS-441524 is mentioned as a promising option. Additionally, supportive care including fluid drainage, anti-inflammatory medications, and nutritional support can be vital in managing symptoms and improving quality of life. It's important to note that while GS-441524 has shown positive results, it's not officially licensed in many countries, and veterinary guidance is crucial.

Preventatively, reducing exposure to the feline coronavirus, which can mutate into FIP, involves maintaining good hygiene, regular veterinary check-ups, and managing multi-cat environments carefully to prevent the spread of infections. Although there is no guaranteed way to prevent FIP, strengthening a cat’s overall health and immune system can help reduce the risk of severe outcomes if the virus is contracted.

For those considering adoption or breeders, genetic factors have been suggested in susceptibility to FIP, so knowing the health history of cat lineages might also be useful.

These additions provide a fuller picture of the nature of Wet FIP, its impact on cats, and the approaches available for managing the disease.


Dry FIP (Feline Infectious Peritonitis) is a form of a serious viral disease in cats, caused by a mutation of the feline coronavirus. Unlike its counterpart, wet FIP, which is characterized by the accumulation of fluid in the abdomen or chest, dry FIP does not lead to fluid buildup. Instead, it manifests through the formation of granulomas—firm masses or nodules—which can cause significant damage to the organs and tissues.


The progression of dry FIP is generally slower and the symptoms less obvious, making it harder to detect early. Some signs of dry FIP include weight loss, lethargy, and changes in appetite. As the disease progresses, it may cause more specific issues depending on which organs are affected by granulomas. For instance, if the kidneys or liver are involved, it could lead to worsening organ function.


The underlying causes of dry FIP are similar to those of wet FIP, revolving primarily around an immune system that fails to effectively combat the virus. This failure allows the virus to proliferate and the immune response to cause inflammation, leading to the formation of granulomas.


Due to its subtle onset and varied symptoms, dry FIP is notoriously difficult to diagnose. Symptoms that might point to dry FIP include chronic weight loss, intermittent fever, and organ-specific issues such as kidney failure or liver abnormalities. As the disease progresses, neurological symptoms might develop if the central nervous system is affected, potentially leading to seizures or paralysis.


Early and accurate diagnosis is crucial but challenging, often resulting in a higher fatality rate for dry FIP compared to wet FIP due to delays in starting appropriate treatments.

Treatment Options

Currently, there are 3 treatment options for FIP:

  1. GS-441524 with approximately 90% success rate.

  2. Remdesivir with approximately 80% success rate.

  3. Molnupiravir with approximately 60% success rate.

Diagnostic Challenges

Dry FIP poses significant diagnostic challenges due to its non-specific symptoms that can mimic other diseases. Advanced diagnostic methods, such as PCR testing to detect viral RNA, and a thorough analysis of the cat's history and clinical signs, are often necessary. Additionally, biopsies or fine-needle aspirates of affected tissues may be required to confirm the presence of granulomas.

Behavioral and Environmental Impact

Cats with dry FIP may exhibit behavioral changes due to discomfort or pain. These can include increased irritability, reduced interest in play or interaction, and hiding. Environmental management, such as providing a quiet and comfortable resting area, can help improve the quality of life for these cats. It's also important for pet owners to monitor their cat’s behavior and physical condition closely and adjust care as needed.

Understanding the complex nature of dry FIP and the integrated approach needed for care is crucial for managing this disease. This includes ongoing veterinary care, monitoring, and adjustments to treatment plans based on the progression of the disease and the cat's response to treatment.

"The symptoms of FIP (Feline Infectious Peritonitis) can vary widely depending on whether a cat has the wet or dry form of the disease, but there are several common symptoms across both types:"

Common Symptoms of FIP:
  • Anorexia and Weight Loss: Cats with FIP often experience a significant loss of appetite and weight. This is due to their bodies struggling to absorb nutrients effectively. The lack of appetite, possibly accompanied by nausea, leads to progressive weight loss.

  • Fatigue and Weakness: FIP typically causes cats to become lethargic and weak. They may show less interest in usual activities, preferring to sleep more than usual and displaying a general lack of energy.

Additional Symptoms:

  • Fever: Fluctuating or persistent fevers that don't respond to typical treatments can also be a sign of FIP.

  • Abdominal Swelling: In cases of wet FIP, fluid accumulation in the abdomen can cause noticeable swelling.

  • Breathing Difficulties: If fluid accumulates in the chest cavity in wet FIP, it can lead to breathing issues.

  • Neurological Symptoms: Particularly in dry FIP, neurological signs such as seizures, uncoordinated movements, or behavioral changes might occur as the disease progresses and affects the nervous system.


Each type of FIP presents challenges in diagnosis due to the overlap of symptoms with other diseases, and the severity of the symptoms can vary greatly from one cat to another. Managing FIP requires a comprehensive approach, focusing on alleviating symptoms and improving the quality of life, as there is currently no definitive cure.

"Frequently Asked Questions"


Is FIP contagious among cats?

Yes, FIP can spread among cats but not directly. The root cause is the feline coronavirus (FCoV), which is commonly shed in the saliva, feces, and urine of infected cats. Cats can contract the virus by coming into contact with these bodily fluids or contaminated environments such as litter boxes or surfaces.


How is FIP transmitted in cats?

Transmission of FIP typically occurs through contact with infected feces. Cats can ingest the virus by using contaminated litter boxes or through grooming. Additionally, the virus can be airborne, spread through droplets when an infected cat sneezes or coughs. Although less common, transmission from an infected mother to her kittens, either in utero or through breastfeeding, can occur. It's also possible for the virus to spread via fomites—objects or materials which are likely to carry infection.

Can humans catch FIP from cats?

No, humans cannot catch FIP. The virus responsible for FIP, while a coronavirus, is specific to felines and does not infect humans. However, maintaining good hygiene, such as washing hands after handling pets, is still crucial to prevent other possible infections.


Additional Precautions:

It's important for people who interact with cats, especially in multi-cat environments, to maintain cleanliness to prevent the spread of the virus among cats. Regular cleaning of cat areas and thorough hand washing after contact with cats can help control the spread of the virus.

Each type of FIP presents challenges in diagnosis due to the overlap of symptoms with other diseases, and the severity of the symptoms can vary greatly from one cat to another. Managing FIP requires a comprehensive approach, focusing on alleviating symptoms and improving the quality of life, as there is currently no definitive cure.

The lifespan of cats diagnosed with Feline Infectious Peritonitis (FIP) varies widely, depending on factors such as the form of FIP (wet or dry), the severity of the disease, and the individual cat's immune response. Generally, cats with wet FIP may survive for a few weeks to several months, while those with dry FIP might live for several months to over a year, depending on how quickly the disease progresses and how effectively their immune system can manage the infection.


Symptoms of FIP can change as the disease advances and will vary based on the cat’s immune health. If you observe any symptoms associated with FIP in your cat, it’s crucial to seek veterinary care promptly. Early detection and treatment can significantly affect the management of the disease and potentially improve outcomes.


If you have questions about FIP or need guidance on its treatment, don't hesitate to reach out to your vet or contact us through our LINE, Facebook, or Instagram for more detailed information. Early and proactive management is key in dealing with this serious condition.

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