An asymptomatic infection means the cat has neither diarrhoea nor any other noticeable symptoms. FCoV infection alone is not a diagnosis of FIP. FIP remains a serious disease, but its prognosis has changed: many affected cats can recover with antiviral treatment planned by a vet.
When to see a vet urgently
Contact a vet promptly if your cat develops any of the following:
- Breathing becomes difficult, noticeably faster at rest or open-mouthed.
- The abdomen enlarges while your cat loses weight, becomes lethargic or stops eating.
- Your cat staggers, has seizures or develops limb weakness.
- The appearance of an eye or vision changes suddenly.
- A kitten has severe diarrhoea and becomes subdued or stops eating.
You can find a vet near you. These symptoms are not assessed solely from a previous coronavirus test result.
Overview
FCoV belongs to the Coronaviridae family. There are two forms:
- feline enteric coronavirus, which causes mild digestive disturbances
- a mutated variant that triggers FIP, in its wet or dry form
These terms describe the clinical picture. In an ordinary intestinal infection, the virus multiplies mainly in cells lining the intestines. In the development of FIP, changes in viral properties allow it to multiply in certain white blood cells, while the cat's immune response also contributes to disease development. Inflammation centres around blood vessels and can damage many organs.
Wet and dry FIP are not completely separate diseases. Signs can overlap and change over time. Fluid can accumulate in the abdominal or chest cavity, but FIP can also occur without a visible fluid collection. An enlarged abdomen is therefore not an essential symptom of FIP.
The virus spreads mainly through faeces: cats acquire it by using a shared litter tray or licking contaminated fur. Large amounts of virus are shed into the environment, particularly in crowded conditions.
A cat that looks healthy can shed the virus. Shedding can continue for a long time or be intermittent, so symptoms ending does not, on its own, prove the virus has gone. In multi-cat environments, cats can be exposed again even if shedding by one animal stops for a time.
Causes
The main source of infection is a cat carrying FCoV. Routes of transmission include:
- using a shared litter tray, the main route
- direct contact with affected cats
- contaminated food bowls, toys and sleeping places
- mechanical transfer on human hands or shoes
The usual chain of transmission involves enteric coronavirus. In most FIP cases, the changes associated with disease develop within an individual cat, and FIP does not usually spread in the same way as ordinary intestinal infection. However, an absolute guarantee of non-transmissibility should not be given: rare outbreaks and an unusual FCoV strain that spread in Cyprus, for example, have been described. Your vet assesses unusual clusters separately.
Risk factors
Infection occurs most often in:
- kittens and young cats
- cats living in shelters and breeding catteries
- animals in multi-cat homes
- cats with weakened immune systems
- pedigree cats, with some lines known to be more susceptible to FIP
This list combines risks of exposure and of developing FIP, which are not the same thing. A large group of cats increases opportunities for faecal exposure, while young age is particularly a risk factor for FIP. Breed or an affected relative does not mean an individual cat will definitely develop the disease. Future FIP in a cat without symptoms cannot be inferred simply from belonging to an at-risk group.
Symptoms
In most cats, coronavirus infection causes no symptoms or only mild diarrhoea. Possible signs include:
- intermittent diarrhoea
- soft or poorly formed stools
- occasional vomiting
- weight loss in a kitten with heavy exposure to infection
⚠️ The danger arises if the virus mutates and causes FIP, whose signs include abdominal fluid accumulation, fever, granuloma formation and internal organ damage.
Early signs of FIP may include persistent fever, reduced appetite, weight loss or poor growth in a kitten. Fluid in the chest cavity can make breathing difficult. Inflammation inside the eye can change its colour or impair vision, and nervous system damage can cause staggering or seizures. Diarrhoea alone does not indicate that this disease is developing.
The same symptoms also occur in other diseases. Cancer, heart disease and other infections, for example, can resemble FIP. Do not decide the cause of fever or abdominal enlargement at home from the fact that your cat once had a positive FCoV result.
Complications and consequences
Although enteric coronavirus itself is rarely dangerous, it can lead to:
- chronic intestinal inflammation
- weakening of the immune system
- development of FIP, the most serious consequence
An ordinary FCoV finding alone does not establish immune deficiency or explain every persistent intestinal disease. Cats carrying the virus without symptoms are common, so other possible causes of diarrhoea are investigated before symptoms are attributed to the virus. Ordinary intestinal infection and the systemic inflammation caused by FIP are assessed as separate clinical situations.
Diagnosis at the vet
Diagnosis is based on:
- faecal PCR testing to detect coronavirus
- serological tests for FCoV antibodies, which do not distinguish the viral form
- blood tests and faecal investigations to rule out other causes of diarrhoea
FCoV can be detected, but it is not possible to predict when the virus will mutate and cause FIP.
Faecal PCR indicates that viral genetic material is present in the sample. Alone, it does not establish the cause of diarrhoea, predict future FIP or confirm a current FIP diagnosis. Because shedding is intermittent, a single negative stool sample may not represent the whole situation. Your vet decides whether follow-up samples are needed, for example to manage infection in a group of cats.
Antibodies indicate exposure. A positive result cannot distinguish mild intestinal infection from FIP, and the antibody level does not predict an individual cat's disease outcome. A cat with FIP can sometimes test negative too. A positive test in a cat without symptoms should therefore not be interpreted as proof of serious disease.
When FIP is suspected, the history, examination findings, complete blood count, blood proteins and other organ values are considered together. Ultrasound and X-rays may reveal fluid or organ changes. None of these findings is decisive on its own in every case. If fluid is available, examining its cells, proteins and viral content is often more useful than a blood sample alone.
Without fluid accumulation, a sample may be obtained from an abnormal organ, using a fine needle for example. A tissue sample can be examined for characteristic inflammation and viral antigen, meaning structural components of the virus. The sampling method also depends on your cat's condition: less demanding methods are preferred where possible in a very ill animal.
Treatment and follow-up
Mild enteric coronavirus infection often needs no specific treatment. A cat with more severe symptoms may require fluids, nausea treatment and nutritional support. Other causes of diarrhoea are investigated at the same time. A test result in a symptom-free carrier is not equated with the treatment needs of a seriously ill cat.
FIP is now treated with medicines that inhibit viral replication, following a vet's plan. The treatment decision depends on the likelihood of the diagnosis and the patient's situation. Selecting the medicine, checking availability and monitoring treatment are the treating vet's responsibility. Early recognition allows treatment to begin before the disease progresses.
An antiviral alone is not always enough initially. Your cat may need nutritional support, correction of fluid balance, pain relief or removal of fluid that interferes with breathing. Neurological symptoms receive the treatment they require. Follow-up investigations monitor weight and changes in blood values as well as symptoms.
At home, record appetite, weight changes, activity and any eye or mobility symptoms. Improvement is not a reason to change medication yourself. Some patients can relapse, so report new symptoms to the clinic after initial recovery too. The prognosis depends on disease severity and treatment response.
Prevention
Completely protecting a cat against FCoV is difficult, but risk can be reduced through:
- keeping no more than 3–4 cats at home
- regular litter tray cleaning and disinfection
- keeping food bowls and resting areas separate
- minimising stress
- breeding and housing practices that avoid overcrowded groups
- an FCoV vaccine exists, but its effectiveness is limited and it is rarely used
Cat numbers are not a precise safety threshold: a small, stable group, adequate resources and reduced faecal contamination matter more than one maximum number for every home. Remove faeces from litter trays and keep feeding places separate from the area around them. Clean and disinfect trays and equipment with animal-safe products according to their instructions.
The vaccination point needs clarification: FIP vaccination is not generally recommended because evidence of clinically meaningful protection is insufficient. Many kittens have already been exposed before this vaccine could be considered. Vaccination does not replace hygiene, uncrowded housing or examination of an ill cat.
What it means for owners
Feline coronavirus is a common infection that is usually mild. The risk of mutation and possibility of FIP make it a serious concern. Remember that intermittent diarrhoea may be a reason for faecal testing. Prevention is particularly important in shelters and multi-cat homes.
Note: this material provides general information and does not replace veterinary advice. Contact a vet immediately if symptoms appear.
Frequently asked questions
Does a positive coronavirus test mean FIP?
No. Faecal PCR detects viral genetic material and an antibody test indicates exposure. Assessing FIP requires symptoms, examination findings and results from suitable samples to be considered together.
Can a cat recover from FIP?
Yes. Antiviral treatment has changed the prognosis, and many cats recover. The disease still needs prompt veterinary assessment, individual treatment and follow-up.
Is feline coronavirus the same as the human COVID-19 virus?
No. FCoV is a different virus from SARS-CoV-2, and feline enteric coronavirus is not considered transmissible to people. Normal hand hygiene is still part of handling litter trays.
Do all cats in the same home need testing immediately?
The need for testing depends on symptoms, the group of animals and the aim of testing. Carrying the virus without symptoms is common, and a single result alone does not establish other cats' future FIP risk.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- Guideline for Feline Infectious Peritonitis, European Advisory Board on Cat Diseases, accessed 2026-11-03.
- Feline Enteric Coronavirus Infection, Merck Veterinary Manual, accessed 2026-11-03.
- Feline Infectious Peritonitis, Cornell Feline Health Centre, accessed 2026-11-03.
- Feline Infectious Peritonitis, ASPCApro, accessed 2026-11-03.
- Feline Infectious Peritonitis, Merck Veterinary Manual, accessed 2026-11-03.
- 2024 guidelines for the vaccination of dogs and cats, World Small Animal Veterinary Association, accessed 2026-11-03.