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A cat with a persistent fever, weight loss, or unusual tiredness may have a serious underlying illness. Some conditions can be difficult to identify because their symptoms resemble those of other feline diseases.
Feline Infectious Peritonitis (FIP) is a potentially life-threatening disease associated with feline coronavirus. Although diagnosis can be challenging, advances in antiviral treatment have significantly improved outcomes for many affected cats.
What Is Feline Infectious Peritonitis?
FIP develops in a small proportion of cats infected with feline enteric coronavirus (FCoV). Most cats exposed to this common virus do not develop FIP.
In affected cats, changes in the virus and the cat's immune response can cause widespread inflammation across different organs.
Young cats, particularly those under two years old, and cats living in crowded environments may be at increased risk.
What Are the Symptoms of FIP in Cats?
Feline Infectious Peritonitis can produce different symptoms depending on which organs are affected.
Common warning signs include:
- Persistent or recurring fever
- Reduced appetite
- Unexplained weight loss
- Lethargy or weakness
- Abdominal swelling
- Difficulty breathing
- Changes in eye appearance
- Poor coordination or other neurological problems
Not every cat develops all these symptoms. Some show gradual changes, while others become seriously ill more quickly.
Wet FIP vs Dry FIP: What's the Difference?
FIP is often described as having two forms, although some cats show features of both.
Wet FIP (Effusive Form)
This form involves fluid accumulating inside body cavities.
Possible signs include:
- Enlarged or swollen abdomen
- Breathing difficulties caused by fluid in the chest
- Reduced appetite
- Fever and weakness
Dry FIP (Non-Effusive Form)
Dry FIP causes inflammation in organs without substantial fluid accumulation.
Signs may include:
- Persistent fever
- Weight loss
- Eye inflammation or vision changes
- Neurological symptoms
- Organ-related health problems
Both forms require prompt veterinary attention.
How Does FIP Spread Between Cats?
The common feline coronavirus associated with FIP spreads mainly through fecal contamination, particularly in environments where cats share litter boxes.
However, FIP itself is not generally considered directly contagious in the same way as common respiratory infections. Most affected cats develop FIP after changes in coronavirus infection within their bodies.
Good litter-box hygiene and reducing overcrowding can help limit exposure to coronavirus.
How Is FIP Diagnosed?
Diagnosing Feline Infectious Peritonitis can be complicated because no single routine test reliably confirms every case.
Veterinarians may use several methods together:
- Physical examination: Assessing fever, weight loss, abdominal swelling, and other clinical signs.
- Blood tests: Looking for abnormalities such as increased globulin levels, changes in albumin, anemia, or inflammation.
- Ultrasound or X-rays: Checking for fluid accumulation and organ abnormalities.
- Fluid analysis: Examining fluid collected from the abdomen or chest when present.
- Coronavirus testing: Performing PCR testing or other laboratory analyses to help confirm the suspected diagnosis alongside the cat’s symptoms and clinical findings.
- Tissue testing: In selected cases, examining tissue samples for stronger evidence of FIP.
A positive feline coronavirus antibody or PCR test alone does not establish that a cat has FIP.
Veterinarians interpret results alongside the cat's symptoms, examination findings, and other possible diagnoses.
Can Feline Infectious Peritonitis Be Treated?
Yes. Feline Infectious Peritonitis was once considered almost universally fatal, but antiviral treatments have changed the outlook.
Antiviral medications such as GS-441524 and, in some veterinary settings, remdesivir can be effective when prescribed and monitored appropriately.
Treatment typically requires a structured course, follow-up examinations, and blood-test monitoring. Availability and regulatory approval vary by country.
Supportive treatment may also be necessary to manage dehydration, nutritional problems, or other complications.
Owners should seek veterinary advice promptly rather than buying unverified antiviral products or treating without professional supervision.
How Can You Reduce the Risk of FIP?
No method can guarantee protection against FIP, but reducing exposure to feline coronavirus and maintaining a healthy living environment may help.
Practical steps include:
- Cleaning litter boxes frequently
- Providing enough litter boxes for multi-cat households
- Avoiding overcrowding
- Reducing stress during household changes
- Maintaining appropriate nutrition and veterinary care
- Monitoring kittens and newly adopted cats for illness
Routine FIP vaccination is generally not recommended because evidence of effectiveness is limited.
When Should You See a Veterinarian?
Seek prompt veterinary attention if your cat develops persistent fever, unexplained weight loss, abdominal swelling, reduced appetite, or unusual weakness.
Breathing difficulties, seizures, or significant neurological changes require emergency veterinary care.
Early evaluation matters because timely treatment can make a substantial difference for cats diagnosed with FIP.
Support Your Cat's Everyday Health
Managing serious infectious diseases requires veterinary care, but everyday preventive measures still support a cat's overall well-being.
A clean environment, appropriate nutrition, routine veterinary exams, and veterinarian-recommended parasite prevention support responsible long-term care.
Explore cat health and parasite-care products at 79pets.com for everyday preventive-care options.
Important: Flea, tick, and deworming products do not prevent or treat FIP. Cats with suspected FIP need prompt veterinary assessment and appropriate antiviral treatment.
Related Cat Health Guides
Explore these additional articles we have already prepared for 79pets to understand other important feline infections.
- Feline Leukemia Virus (FeLV): Symptoms, Testing, and Prevention — Learn how FeLV affects the immune system, how testing works, and ways to reduce exposure.
- FIV in Cats: Symptoms, Transmission, Testing, and Care — Understand how FIV spreads, which symptoms to watch for, and how infected cats can be cared for.
- Cat Panleukopenia: Symptoms, Treatment, and Prevention — Discover the warning signs of a serious viral infection and the importance of vaccination.
Final Thoughts
Feline Infectious Peritonitis is a serious condition, but effective antiviral treatment has brought new hope for affected cats.
Recognizing unusual symptoms, obtaining an accurate veterinary diagnosis, and beginning appropriate treatment promptly can greatly improve a cat's chances of recovery.
