However, FIV infection does not mean a cat already has severe immunodeficiency or will inevitably have a short life. Many remain well for years and may have a normal lifespan. The opening prevalence figures cannot be used as the infection probability for cats in every country: results depend on the region, health and exposure of the cats studied. A shelter background alone does not establish infection.
When to see a vet urgently
An FIV-positive cat needs immediate assessment if it has any of these signs:
- difficulty breathing or open-mouth breathing;
- collapse, altered consciousness or severe weakness;
- continuous or repeated seizures.
Contact an emergency practice: find a vet near you.
Overview
FIV is a lentivirus in the retrovirus family. It enters immune cells, including T lymphocytes and macrophages, alters their function and gradually damages the body's defences. The disease progresses slowly: months or years may pass after infection before obvious symptoms appear. A cat carrying FIV can look healthy but still infect other cats.
Routes of transmission
FIV is mainly transmitted:
- Through bites: the virus is present in saliva, and transmission most commonly occurs during cat fights
- From a mother to kittens during pregnancy or nursing
- Less commonly through blood transfusion
Important: the virus is fragile outside the body and is quickly destroyed, so it does not usually spread through everyday contact, such as shared food bowls, litter trays or living in the same home.
Mother-to-kitten transmission is much rarer under natural conditions than transmission through bites. A kitten from a positive mother should therefore not be assumed infected without appropriate testing. Blood transfusion risk is reduced by screening donor cats. Ordinary touching at home does not spread FIV to a person, dog or another cat in the same way as a deep bite from an infected cat.
The transmission risk among cats living peacefully together is low, but cannot be promised to be zero. Decisions about living together depend on behaviour, health and test results. Cats that fight or inflict bite wounds are separated. Do not introduce a new cat directly into the same space without assessing infection status and compatibility.
How the disease develops and its stages
After infection, the virus infects T lymphocytes and other immune cells. The disease has several stages:
- Acute stage: transient fever, enlarged lymph nodes and tiredness may occur 1–3 months after infection
- Asymptomatic stage: this can last years; the cat looks healthy, but immunity slowly weakens
- Immunodeficiency stage: recurrent severe infections, chronic inflammation, weight loss, oral inflammation, skin disease and tumours
These stages are not a precise timetable for predicting an individual cat's condition. Cats may remain symptom-free for a long time, and not all progress to severe end-stage disease. A positive antibody test provides information about infection status but does not alone show how well the immune system functions or whether a current symptom needs treatment.
Symptoms of FIV in cats
Symptoms appear gradually and can be very varied:
- Chronic respiratory, skin and intestinal infections
- Oral inflammation, including stomatitis and gingivitis
- Weight loss and general deterioration
- Prolonged fever and listlessness
- Enlarged lymph nodes
- Neurological signs, including behavioural changes and seizures
- Increased susceptibility to parasites, fungi and bacteria
- Tumours, including lymphomas and sarcomas
Similar symptoms also occur without FIV infection. A previous diagnosis therefore does not automatically explain every fever, weight change or lump. The vet distinguishes changes directly related to the virus, infections encouraged by reduced immunity and other common feline illnesses. Oral pain or urinary symptoms, for example, are investigated and treated rather than left as consequences of the immunodeficiency diagnosis alone.
Complications and consequences
FIV is dangerous because it causes:
- Profound immunodeficiency
- Chronic inflammatory disease
- Secondary infections that are difficult to treat
- Tumours
- A shortened lifespan
An infected cat's lifespan depends on its general condition and care. With good care, some cats live 5–10 years after diagnosis.
The stated 5–10 years is not a deadline or a prognosis describing every cat. Other infections, oral health, nutritional status and how treatable a diagnosed illness is all matter, for example. A positive FIV result in a symptom-free cat is not itself a reason for euthanasia. If quality of life declines, decisions depend on suffering and treatment possibilities, rather than the virus's name alone.
Veterinary diagnosis
FIV is detected through:
- Rapid tests, including IFA and ELISA, to identify blood antibodies
- PCR testing to detect viral DNA
- Repeat tests after a few weeks in uncertain cases
- Additional tests, including a blood count, biochemistry, ultrasound and X-rays, to detect complications
The most common in-practice screening test looks for FIV antibodies, rather than the virus itself. IFA is usually a laboratory confirmation method, so the methods listed above are not all the same kind of rapid test. An unexpected positive result in a healthy cat with little exposure is checked with another method or a new sample before lasting conclusions are drawn.
After a recent bite, a negative result may be too early because detectable antibodies have not yet formed. Repeat testing is timed from possible exposure; a vague wait of a few weeks does not suit every situation. A kitten's antibodies may come from its mother and not indicate its own infection. Previous FIV vaccination in another country may also affect some antibody tests, so tell the vet the vaccination history.
PCR can help investigate conflicting results but is not an infallible confirmation. The method's ability to detect different viral strains and the amount of virus in the sample affect the result. A negative PCR alone therefore does not automatically overturn repeatedly positive antibody findings. A blood count and imaging assess health and other diseases; they do not replace an infection test.
Treatment and follow-up
Routine treatment cannot eliminate FIV from a cat's body. Care targets diagnosed illnesses, such as a bacterial infection, painful oral inflammation or a tumour. A symptom-free positive cat does not automatically need antibiotics. Antivirals may be considered in selected situations, but benefits and adverse effects are assessed individually, and no curative medication suits every cat.
Oral examination is part of monitoring. Bad breath, cautious eating or drooling may indicate oral disease needing treatment. Necessary dental procedures or other surgery are not withheld solely because of FIV status: general health and any immune dysfunction are assessed beforehand. Pain relief is also planned as for other cats.
At home, record appetite, weight trends, activity and recurring symptoms. Follow-up examinations include the mouth, skin, eyes and lymph nodes. Blood and urine tests help identify changes before obvious deterioration. Do not wait for a planned check-up if your cat becomes ill again or a familiar problem does not improve as expected.
Provide complete, balanced cat food. Raw meat and unpasteurised dairy products increase avoidable exposure to pathogens. Weight or muscle loss needs investigation even if your cat still appears to eat. Supplements do not remove the virus, and dietary correction alone does not replace treatment of inflammation or another diagnosed illness.
Prevention
- Testing all new cats before they live together
- Limiting contact with outdoor cats
- Keeping cats indoors and avoiding fights
- Neutering to reduce aggression and biting
- Regular veterinary health checks
- Good nutrition and careful care to support immune defences
FIV vaccine availability differs between countries, so minimising infection risk is the main preventive measure.
FIV vaccines have been used in some countries, but protection is incomplete and vaccination does not replace bite prevention. Availability and licensed use must be checked by country. Vaccination against other infections is assessed individually by the vet; FIV positivity does not mean automatically stopping every vaccination. The cat's health and exposure risks affect the choice.
What it means for owners
- FIV does not infect people or other animal species
- An infected cat can live a long time with good care
- Regular veterinary monitoring and minimising stress are important
- An FIV-positive cat needs a safe environment without exposure to infections or fights
Safe indoor life includes quiet resting places and opportunities to avoid other animals. In a multi-cat home, watch whether every cat can eat and rest without intimidation. A cat can have a good home and daily life after an FIV diagnosis. Any restrictions on living together are planned to reduce infections and stress, rather than based solely on a positive test result.
This text provides information only and does not replace veterinary care. If your cat develops symptoms, seek veterinary attention.
Frequently asked questions
Can FIV infect a person or dog?
FIV is adapted to cat species and does not infect people or dogs. However, a cat's other infections may still require routine hygiene measures. FIV positivity does not remove the need to investigate the actual cause of a skin problem, for example.
Does a positive result mean the cat is seriously ill?
No. A cat can remain symptom-free for a long time, and an unexpected screening result may need confirmation. Clinical examination and appropriate additional tests establish both infection status and whether there is an illness currently needing treatment.
Can an FIV-positive cat live with another cat?
Risk is low among compatible cats that do not bite each other, but individual assessment is needed. Biting, tensions and new cat contacts change the situation. If safe coexistence cannot be ensured, keep the cats separate.
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 Immunodeficiency Virus, ABCD, accessed 2026-11-03.
- Feline Immunodeficiency Virus (FIV), Cornell Feline Health Centre, accessed 2026-11-03.
- Feline Immunodeficiency Virus (FIV), MSD Veterinary Manual, accessed 2026-11-03.
- 2020 AAFP Feline Retrovirus Testing and Management Guidelines, Journal of Feline Medicine and Surgery, accessed 2026-11-03.
- Feline Immunodeficiency Virus (FIV), ASPCApro, accessed 2026-11-03.
- 2020 AAHA/AAFP Feline Vaccination Guidelines: Frequently Asked Questions, AAHA, accessed 2026-11-03.
- Initial Triage and Resuscitation of Small Animal Emergency Patients, MSD Veterinary Manual, accessed 2026-11-03.