Cats get FIP (feline infectious peritonitis) when a common feline coronavirus mutates inside the cat and triggers an abnormal immune response. The virus itself is widespread in multi-cat environments, but only a small fraction of infected cats go on to develop FIP. Key points:
- How it spreads: Feline coronavirus (FCoV) is typically transmitted via the fecal-oral route, often through shared litter boxes, contaminated surfaces, or close contact with other cats. Infected cats can shed the virus in their feces for weeks to months, and some may continue shedding for life in some cases. Environment and stress can influence transmission and disease risk. This is especially common in crowded settings such as shelters, catteries, or households with many cats. [web results indicate FCoV transmission via feces and environmental contamination; multi-cat housing increases exposure and risk]
- Mutation to FIP-causing form: Most cats infected with FCoV do not develop FIP. FIP occurs when the virus mutates in a way that enables it to invade body tissues and when the immune response to the virus becomes dysregulated, leading to widespread inflammation. There is no single test that definitively distinguishes mutated FCoV causing FIP from the benign intestinal form in every case, making diagnosis challenging. [sources describe mutation and immune-mediated pathogenesis]
- Common risk factors: Very young cats (often under 2 years) and older cats can be more susceptible due to immune system maturity or decline. Stressful or crowded conditions, genetic predisposition (including some purebred lines), and ongoing exposure to the virus increase risk. [several veterinary sources discuss age, genetics, and environmental risk]
- Forms and signs: FIP presents in two main forms—wet (effusive) with fluid accumulation in body cavities, and dry (non-effusive) with organ-specific inflammation. Typical signs include fever not responding to antibiotics, weight loss, letharg, and abdominal distension or fluid accumulation if the wet form develops. Diagnosis is often based on a combination of history, clinical signs, imaging or fluid analysis, and supportive tests; confirmation can be complex. [standard veterinary descriptions of wet and dry FIP and diagnostic challenges]
- Prevention and management: Preventing FIP is about reducing high-risk exposure (e.g., good litter box hygiene, minimizing crowding, reducing stress) and monitoring at-risk cats closely. There is no universally effective vaccine for FIP in all settings, and treatment options vary; recent advances in antiviral therapies have improved outcomes for some cats in certain regions, but access and effectiveness can differ. Early veterinary involvement is essential if signs appear. [general guidance found in veterinary literature and clinics]
If you’d like, I can tailor this to your situation (e.g., number of cats you have, ages, shelter environment, or whether you’re seeking prevention steps or understanding signs to watch for). I can also pull current, specific guidance from reputable veterinary sources to provide up-to-date recommendations.
