What is F.I.P.?
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Feline Infectious Peritonitis (FIP)
Feline Infectious Peritonitis (FIP) is a serious and often fatal viral disease in cats. However, recent breakthroughs in treatment have transformed the prognosis from a death sentence to a manageable and often curable condition. This guide, based on a veterinarian’s perspective, explores the causes, signs, diagnosis, and new treatment options for FIP.
Understanding the Cause of FIP
FIP is caused by a mutated form of the Feline Coronavirus (FCoV), a virus distinct from the one causing COVID-19. FCoV is extremely common, especially in multi-cat households, where up to 100% of cats may have been infected.
In most cats, FCoV causes no symptoms or only mild, self-resolving diarrhea. The deadly FIP disease develops only when the virus mutates inside a cat’s body and the cat’s immune system reacts in a particular, destructive way. It’s vital to understand that a positive test for FCoV does not mean a cat has FIP, as many healthy cats are carriers of the virus without ever developing the disease.
The Two Forms of FIP
FIP is categorized into two main forms, both of which stem from the same viral mutation but manifest differently depending on the cat’s immune response.
1. Wet (Effusive) FIP
Wet FIP is the most easily recognizable form due to its key characteristic: fluid accumulation in the body cavities. This is a result of vasculitis, a severe inflammation of the blood vessels that makes them “leaky.” This leads to a buildup of a thick, yellowish, protein-rich fluid.
- Abdominal Effusion: Fluid in the abdomen causes a distended, bloated appearance. This can lead to a reduced appetite and discomfort.
- Pleural Effusion: Fluid in the chest cavity puts pressure on the lungs, causing severe respiratory distress, rapid breathing, and coughing. This is a life-threatening emergency.
2. Dry (Non-Effusive) FIP
Dry FIP does not cause significant fluid buildup. Instead, it is characterized by the formation of granulomas—small, inflammatory masses—in various organs. The signs are highly variable and depend on which organs are affected
- Neurological Signs: FIP affects the brain in approximately 30% of cases, leading to an unsteady gait, tremors, seizures, or behavioral changes.
- Ocular (Eye) Signs: This form of dry FIP affects a cat’s eyes and can cause uveitis (inflammation of the eye’s middle layer), bleeding, or a cloudy appearance. Approximately 30% of FIP cases have eye involvement.
- Internal Organ Damage: Granulomas can form in the liver, kidneys, lungs, or other organs, leading to a range of non-specific signs like fever, lethargy, weight loss, jaundice, and enlarged lymph nodes.
Cats Most at Risk
While FIP can strike at any age, it is most frequently diagnosed in young cats under two years old, with many cases appearing between four and twelve months of age. Cats from multi-cat environments, such as breeding households, are at higher risk due to the ease of FCoV transmission and the potential for stress to weaken their immune systems. Genetic susceptibility also plays a role in a cat’s likelihood of developing the disease.
The Challenge of Diagnosis
Diagnosing FIP is a complex process as no single test can definitively confirm the disease. A veterinarian must assemble a “puzzle” of information, including:
- Clinical Signs and Risk Factors: Evaluating the cat’s symptoms, age, and environment.
- Routine Blood Tests: Looking for nonspecific but suggestive findings like elevated globulins, anemia, or low lymphocytes.
- Fluid Analysis: If a cat has fluid, analyzing a sample for high protein content and specific cell types is highly suggestive of FIP. Further confirmation can be obtained via PCR testing on the fluid.
- Advanced Diagnostics: In dry FIP cases, a biopsy or aspirate of an affected organ may be needed to confirm the diagnosis by identifying granulomas and the presence of FCoV.
Important Note: A positive coronavirus antibody test (serology) is of very limited value for diagnosis, as many healthy cats have antibodies from prior exposure.
Breakthroughs in FIP Treatment
FIP was once considered a universally fatal disease, but recent developments in antiviral medications have brought remarkable hope. These drugs are highly effective at curing FIP
- EIDD-1931 (e.g., Petcore EIDD): A newer, often more affordable oral antiviral, EIDD-1931 has demonstrated a high success rate for both wet and dry FIP. It requires twice-daily dosing and may not be suitable for neurological or ocular cases. A notable product is Petcore EIDD, which is often given as “food supplement capsules.” Treatment usually involves twice-daily oral capsules for at least 60 days. While effective, it is essential to use legal, quality-assured medications, as “black market” supplies carry risks of unknown content and safety. Untill this day Petcore EIDD has a curation rate of
- GS-441524: This antiviral is regarded as the “gold standard” for FIP treatment. It works against both wet and dry forms, including neurological and ocular cases. Treatment usually involves daily injections or oral capsules for at least 84 days. Although effective, it can be expensive, and some cats may feel pain at the injection site.
Prevention Strategies
Given that a vaccine has limited efficacy (as kittens are often exposed before they can be vaccinated), prevention focuses on minimizing stress and reducing the viral load in a cat’s environment, especially in multi-cat households.
- Avoid Overcrowding: Keep cats in small, stable groups.
- Good Hygiene: Provide one litter box for every two cats and clean them daily. Place litter boxes away from food and water.
- Stress Reduction: Maintain a low-stress environment with plenty of enrichment.
In breeding households, additional measures can be taken, such as breeding from older, less-shedding cats, isolating pregnant queens, and ceasing breeding from cats that repeatedly produce FIP-affected kittens.
By understanding FIP and applying these preventative and treatment measures, veterinarians and cat owners can work together to successfully combat this once-devastating disease.