What It Means If Your Cat Is Diagnosed with Feline Infectious Peritonitis (FIP)

Feline infectious peritonitis (FIP) is a serious viral disease that affects around 2% of domestic cats. It happens when a mutation of the feline coronavirus (FCoV) triggers an abnormal immune response. This disease often leads to fluid buildup in the abdomen or chest, resulting in swelling and difficulty breathing.

FIP primarily occurs in young cats, but it can affect cats of any age, especially those with weakened immune systems. Signs of FIP include fever, weight loss, lethargy, and decreased appetite. Some cats may also develop neurological symptoms if the virus affects their brain. An estimated 15,000 US cats are diagnosed with FIP per year. FIP is one of the biggest killers of kittens and young adult cats.

Feline infectious peritonitis (FIP) is caused by a mutation of the feline coronavirus (FCoV). Most cats carry a strain of this virus without showing any symptoms. However, in some cases, the virus can mutate and trigger an abnormal immune response in the cat's body.

When this mutation occurs, it leads to FIP, an inflammatory disease that can affect various organs, including the liver, kidneys, and nervous system. Kittens and young cats are more vulnerable to developing FIP, but cats of any age are at risk.

FIP typically spreads through contact with infected cat feces, urine, or saliva. Stress, overcrowding, and poor hygiene can increase the likelihood of the virus spreading and mutating. It's important for cat owners to maintain a clean environment and monitor their pets for any signs of illness.

Feline coronavirus (FCoV) is a very contagious RNA virus and quite common among cats. Many cats, especially those in multi-cat households or shelters, get exposed to the virus at some point in their lives. Studies suggest that up to 90% of adult cats may carry the coronavirus without showing any symptoms.

However, the development of feline infectious peritonitis (FIP) is much less common. Only a small percentage of cats infected with FCoV—estimated between 5% and 10%—go on to develop FIP. Thus, while FCoV is widespread, FIP is relatively rare. Understanding this difference helps cat owners recognize that not all cats exposed to the coronavirus will get FIP. Maintaining a healthy environment and managing stress can reduce the risk of FIP in cats that have been exposed to FCoV.

1. Direct Contact: Cats can contract FCoV by grooming themselves or each other and ingesting the virus present in feces or saliva.
2. Environmental Contamination: The virus can survive in the environment for a long time, making it easy for cats to pick it up from contaminated food bowls, litter boxes, or surfaces.
3. Stress and Crowding: Overcrowded living situations, like shelters or multi-cat households, increase the risk of exposure and infection. Stress can also weaken a cat’s immune system, making it more susceptible to the virus.

A cat infected with feline infectious peritonitis may exhibit a variety of clinical signs, which can vary depending on the form of the disease—wet (effusive FIP) or dry (non-effusive FIP). Here are some common signs associated with FIP:

Wet FIP:

1. Fluid Accumulation: A noticeable swelling in the abdomen due to fluid buildup (ascites) or in the chest (pleural effusion), leading to difficulty breathing.
2. Fever: A persistent fever that does not respond to treatment.
3. Lethargy: Extreme tiredness or lack of energy.
4. Weight Loss: A noticeable decrease in body weight and muscle mass.
5. Decreased Appetite: Loss of interest in food or difficulty eating.

Dry FIP:

1. Neurological Signs: Issues like seizures, abnormal behavior, or coordination problems if the central nervous system gets affected.
2. Eye Problems: Changes in eye color, inflammation, or other eye-related symptoms.
3. Fever: Similar to wet FIP, often unexplained and recurring.
4. Weight Loss: Continual decline in weight despite normal or increased appetite.
5. Lethargy: Reduced energy levels and activity.

Cats may develop a combination of these signs, and they can progress quickly. If you notice any of these symptoms, it’s important to consult a veterinarian for a proper diagnosis and potential treatment options. Early intervention can help manage the cat's condition and improve its quality of life.

Diagnosing feline infectious peritonitis (FIP) can be challenging since its symptoms often resemble those of other diseases. Veterinarians use a combination of methods to confirm the diagnosis:

1. Clinical Signs:

Veterinarians start by observing the cat's clinical signs, such as fever, weight loss, lethargy, and fluid accumulation.

2. Blood Tests:

• Fibrinogen Levels: Elevated levels of fibrinogen – a protein involved in forming blood clots in the body – may indicate inflammation.
• Protein Levels: A high total protein level with a high albumin-to-globulin ratio is often seen in FIP cases.

3. Fluid Analysis:

If fluid accumulates in the abdomen or chest, a veterinarian may perform a procedure called abdominocentesis or thoracentesis to collect and analyze the fluid.

• Appearance of Fluid: The fluid often appears yellow and cloudy in wet FIP.
• Protein Content: The fluid typically has high protein levels.

4. Imaging:

X-rays or ultrasounds can help visualize fluid accumulation and assess organ involvement.

5. PCR Testing:

Polymerase chain reaction (PCR) tests can detect FCoV genetic material in blood or fluid samples. However, a positive PCR result does not confirm FIP, as many cats carry FCoV without developing the disease.

6. Biopsy:

In some cases, a biopsy of affected organs can provide definitive evidence of FIP, showing characteristic lesions and immune responses.

7. Response to Treatment:

Sometimes, a veterinarian may prescribe treatment for FIP and monitor the cat's response. Improvement in symptoms can support the diagnosis.

Due to the complexity of FIP, a definitive diagnosis often requires multiple tests and evaluations. If you suspect your cat may have FIP, consult a veterinarian for thorough testing and a proper diagnosis.

There are treatment options for feline infectious peritonitis (FIP), but effective management can vary based on the form of the disease and individual circumstances. Here are the primary treatments available:

1. Antiviral Medications:

Cats have shown improvement after treatment with antiviral medications such as molnupiravir, which work by interfering with the enzymes or other biological processes in the FIP virus.

2. Supportive Care:

While antiviral medications target the virus, supportive care helps manage symptoms. This may include:

• Fluid Therapy: Administering fluids to prevent dehydration, especially if there’s fluid accumulation.
• Nutritional Support: Enhancing the cat’s diet to maintain weight and energy levels with special therapeutic foods or prescriptions.
• Anti-inflammatory Medications: Immuno-modulators and immunosuppressant drugs (corticosteroids, cyclophosphamide, ribavirin, and feline interferon) can help reduce inflammation and improve the cat’s comfort.

3. Corticosteroids:

Some veterinarians may prescribe corticosteroids like prednisone to help reduce inflammation and mitigate the immune response. However, they are not a cure and should be used carefully.

4. Palliative Care:

For cats with advanced FIP or those who do not respond to treatment, palliative care focuses on improving quality of life. This includes keeping the cat comfortable and managing symptoms.

5. Regular Monitoring:

Ongoing check-ups are important to assess the cat’s response to treatment and make any necessary adjustments.

While many cats have shown improvement with the introduction of antiviral therapies like molnupiravir, it is essential to consult with a veterinarian to determine the best course of action for your cat. Early diagnosis and prompt treatment can significantly improve the chances of recovery from FIP.

Are certain cat breeds more susceptible to FIP than others?

Certain cat breeds show a higher susceptibility to feline infectious peritonitis (FIP). Research indicates that breeds such as the Abyssinian, Bengal, Burmese, and Himalayan tend to develop FIP more frequently than others.

Genetic factors may play a role in this increased risk, but the exact reasons are still not fully understood. While any cat can contract FIP, the breeds mentioned have higher instances of the disease, especially in young cats. Regardless of breed, it’s important for all cat owners to be aware of FIP and its associated risks.

Also, avoid adopting cats from breeding catteries or taking in colony, stray, or feral cats. They are more likely to carry viruses that contribute to FIP.

What are the best ways to prevent FIP?

Maintaining a clean environment and minimizing stress can help reduce the likelihood of FIP in any cat. Keeping cats as healthy as possible, including preventing infection by other viruses such as feline leukemia virus and calicivirus by appropriate vaccination is likely to decrease the likelihood of FIP. Regular veterinary check-ups also contribute to early detection and management of potential health issues.

Is feline infectious peritonitis fatal?

FIP is one of the biggest killers of kittens and young adult cats. But with early detection, it can be treated and even cured. Infected cats have shown improvement when treated with antiviral medications such as molnupiravir. Your cat’s quality of life can be managed with medications that treat the symptoms of FIP. Also, recent virus research studies show promising results with other antiviral medications, but more research needs to be done.

Is there a test for FIP?

Unfortunately, there is currently no definitive test to diagnose FIP. Due to the complexity of FIP, a definitive diagnosis often requires multiple tests and evaluations. If you suspect your cat may have FIP, consult a veterinarian for thorough testing and a proper diagnosis.

Is a FIP vaccine still available?

There is only one licensed FIP vaccine available, but this vaccine has questionable effectiveness in preventing FIP and it is not routinely recommended by the American Association of Feline Practitioners Feline Vaccine Advisory Panel. The vaccine appears to be safe, but the risks and benefits of vaccination should be weighed carefully. Cat owners should consult their veterinarian to help them decide if their cat should be vaccinated.

VCA

Cornell Feline Health Center