By Dial A Vet Veterinary Team
Feline infectious peritonitis used to be a sentence more than a diagnosis. Families heard the name and prepared for hospice. That story is changing. In many places, including Australia, veterinarians can now discuss legal, clinic-supervised antiviral treatment pathways that have given large numbers of cats a real chance. Hope is appropriate. So is caution: internet powder and imported vials without veterinary oversight are not a safe substitute for a proper work-up.
Key takeaways
- FIP develops in some cats after mutation of ordinary feline coronavirus inside the body. It is not the same as casually "catching FIP" from every coronavirus-positive housemate.
- Wet (effusive) and dry (non-effusive) forms both need veterinary diagnosis.
- Persistent fever, fluid in the belly or chest, eye changes and neurological signs are classic patterns.
- Treatment decisions belong with a veterinarian. Do not dose unverified antivirals at home.
- Related: cat flu, inappropriate mentation in cats.
Wet versus dry FIP
Wet (effusive) FIP produces sticky yellow fluid in the abdomen or chest. Cats may look pot-bellied, breathe hard if the chest is involved, and feel feverish and miserable.
Dry (non-effusive) FIP forms inflammatory lesions in organs, eyes or the nervous system. Signs can include weight loss, jaundice, uneven pupils, cloudy eyes, seizures, wobbliness or behaviour change. Mixed forms occur.
Both start from feline enteric coronavirus that has circulated in multi-cat homes for decades. Only a minority of infected cats develop FIP, usually when the virus mutates and the immune response goes wrong. Young cats, purebreds in some lines, and stressful crowded environments appear over-represented, but any cat can be affected.
Signs that raise concern
- Fever that does not respond as expected to simple care
- Lethargy and steady weight loss
- Swollen belly or difficulty breathing
- Poor appetite lasting days
- Yellow gums or skin
- Eye colour change, squinting or vision trouble
- Tremors, seizures, circling or dull mentation
- Anaemia on bloodwork found during other investigations
When it is an emergency
Seek urgent care for laboured breathing, collapse, seizures, inability to walk, severe jaundice or a cat that stops eating and drinking. Chest fluid can become an immediate breathing crisis.
How vets diagnose FIP
There is no perfect single bedside test for every case. Vets combine history, exam, bloodwork, imaging, fluid analysis (when fluid is present), and sometimes PCR or other lab tests on fluid or tissue. Rival diagnoses include heart disease, bacterial peritonitis, cancer and other infections. A careful clinician rules in and rules out rather than labelling every sick young cat as FIP from a Facebook photo.
Treatment overview
Management has two layers:
- Supportive care: fluids, nutrition, draining uncomfortable fluid when appropriate, eye care and seizure control as needed
- Disease-directed antiviral therapy under veterinary prescription and monitoring where available and lawful in your region
Protocols, product choice and length of treatment are clinical decisions. Relapse monitoring after a course is part of responsible care. Owners sometimes see dramatic improvement within days of clinic-led therapy. That does not mean unfinished courses or shared leftover medicine are safe.
Avoid buying unverified GS-type chemicals from overseas sellers. Contaminated product, wrong concentration and delayed veterinary assessment have harmed cats. If cost is the barrier, ask the clinic about payment plans, charity partners or clinical trial access rather than gambling on grey-market drugs.
Living with multi-cat households
Ordinary feline coronavirus is common in shelters and multi-cat homes. Good litter hygiene, reducing overcrowding stress and isolating highly sick cats help general health. Quarantine panic after every coronavirus-positive faecal PCR is rarely useful, because many healthy cats shed coronavirus. Focus on the sick individual and veterinary advice for the group.
Outlook
With modern clinic-guided antiviral options, many cats that would have died a decade ago now enter remission. Neurological and advanced dry forms can be harder. Early recognition still matters. Celebrate progress without promising every cat the same result.
FAQ
Is FIP contagious to people?
Feline coronavirus and FIP are not human COVID-19. People do not catch FIP from cats.
Should I euthanase as soon as FIP is suspected?
Not automatically. Talk through diagnostics and treatment options with your vet before making end-of-life decisions.
Can vaccines prevent FIP?
Routine cat vaccines protect other diseases. FIP-specific vaccination is not a simple answer for most Australian household cats. Ask your vet what applies locally.
My other cat shared bowls. Will they get FIP?
They may already share enteric coronavirus exposure. Only some cats develop FIP. Monitor health and keep stress low.
Talk with a vet
If your cat has unexplained fever, fluid or neurological signs, a Dial A Vet veterinarian can help you prepare questions for diagnostics and treatment planning. Speak with a Dial A Vet vet.
References
- Addie D, et al. Feline infectious peritonitis: ABCD guidelines.
- Merck Veterinary Manual. Feline infectious peritonitis.
- Australian veterinary guidance on lawful FIP treatment access and monitoring.
- Pedersen NC. Historical and modern perspectives on FIP antiviral therapy.
Disclaimer: Educational only. This page does not replace an examination or advice from your own veterinarian. If you are worried about your pet right now, contact your local vet or nearest emergency animal hospital.