Cats
Published 2026-05-03 • 11 min read
FIP can be frightening, but treatment options and veterinary guidance have changed in recent years. This guide explains the basics in simple language and helps owners prepare better questions.
Compare with similar dog symptom guides: Why is my dog breathing heavy?, Why is my dog coughing?.
FIP stands for feline infectious peritonitis. It is a serious disease linked to feline coronavirus changes inside some cats. FIP can cause fluid buildup, fever, weight loss, eye or neurologic signs, and severe illness.
FIP is a serious condition. This article is educational and should not be used to diagnose or treat your cat at home. Contact your veterinarian quickly if FIP is suspected.
FIP patterns are often described as wet or dry, but real cases can overlap.
Symptoms can be vague at first and may look like other diseases.
There is no single simple home test. Vets use history, exam findings, bloodwork, imaging, fluid analysis, and sometimes specialist input to build a diagnosis.
Veterinary treatment discussions have changed as antiviral options have become more accessible in some settings. Your vet is the right person to discuss legal, safe, and case-specific options.
Fast action matters.
Call urgently for persistent fever, belly swelling, breathing effort, severe lethargy, not eating, eye changes, neurologic signs, or rapid weight loss.
FIP is serious, but prompt veterinary care matters.
FIP was historically considered almost always fatal, but treatment options have changed. Prognosis depends on the cat, disease pattern, timing, and veterinary treatment access.
Early signs may include fever, low appetite, weight loss, tiredness, or vague illness. Some cats later develop fluid, eye signs, or neurologic signs.
FIP itself is not usually considered contagious in the simple way owners fear, but feline coronavirus can spread among cats. Ask your vet about household risk and hygiene.
Diagnosis usually uses a combination of exam findings, bloodwork, imaging, fluid tests, and overall pattern. Your vet may recommend referral or additional testing.
In many regions, veterinarians can discuss antiviral treatment options that were not previously available through standard paths. Ask your vet about current legal and safe options.
Read [symptoms of kidney disease in cats](/blog/symptoms-of-kidney-disease-in-cats) and [why is my cat breathing heavy](/blog/why-is-my-cat-breathing-heavy).