Feline Immunodeficiency Virus in Cats

Feline immunodeficiency virus (FIV) weakens a cat’s immune system and can leave them vulnerable to recurring infections. Because cats often hide illness until disease is advanced, early testing and regular veterinary checkups are especially important.

Talk to a vet

Urgent

Schedule a veterinary visit if your cat may have FIV or has recurrent infections

FIV itself is usually not a sudden emergency, but cats with FIV can develop serious secondary infections, mouth pain, weight loss, fever, eye inflammation, or other complications. Call your vet promptly if your cat seems ill, has been in a fight, or has ongoing symptoms that keep coming back.

Symptoms to Watch For

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Weight loss

Gradual weight loss or poor body condition can be an early sign that chronic illness is developing.

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Gum or mouth inflammation

Painful gingivitis, stomatitis, drooling, bad breath, or trouble eating are common in cats with FIV.

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Fever or swollen lymph nodes

Some cats have fever, low energy, or enlarged lymph nodes, especially early after infection.

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Eye problems

Chronic conjunctivitis, eye inflammation, or squinting may occur with immune dysfunction or secondary infection.

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Vomiting or diarrhea

Digestive upset can happen, especially if secondary infections or chronic inflammation develop.

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Repeated infections

Recurring skin, respiratory, urinary, or other infections are a red flag because FIV weakens immune defenses.

What Causes Feline Immunodeficiency Virus

FIV is a feline-specific virus that attacks the immune system, especially certain white blood cells. The main route of transmission is deep bite wounds from an infected cat, which is why outdoor cats and cats that fight are at greater risk. Casual contact like sharing bowls or mutual grooming is generally not considered an efficient way to spread FIV in stable households. Infected cats may look completely healthy for months or years, so testing matters even when symptoms are subtle.

Primary spread is through bite wounds and saliva from an infected cat
Greatest risk is in outdoor, unneutered male, and fighting cats
Mother-to-kitten transmission can happen but appears uncommon
Sexual transmission is not considered a major route in natural settings
No breed predisposition is consistently recognized; risk is driven more by lifestyle and exposure than breed

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How It's Diagnosed

Veterinarians usually start with a blood screening test that looks for antibodies to FIV, commonly an ELISA-style test. Because antibodies can take weeks to develop after infection, a recently exposed cat may test negative early on and need repeat testing. Positive screening results may need confirmation, especially in kittens or in cats with a complicated testing history. Your veterinarian may also recommend bloodwork, urine testing, and other diagnostics to look for secondary infections, inflammation, anemia, or organ changes.

Initial screening is typically a blood antibody test
Recent exposure may require repeat testing after the antibody window period
Kittens can test positive from maternal antibodies and may need retesting later
Additional tests may include CBC, chemistry panel, urinalysis, and targeted tests for secondary disease
Cats with persistent or recurrent illness should be tested even if they seem low-risk

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Treatment Options

There is no cure that clears FIV infection, so treatment focuses on monitoring health, treating secondary infections quickly, and supporting quality of life. Many FIV-positive cats can live for years, and Cornell notes that infected cats commonly live average life spans if they are otherwise well managed and not also infected with feline leukemia virus. Your veterinarian may recommend regular exams, dental care, parasite prevention, routine lab work, prompt treatment of infections, and keeping your cat indoors. Some antiviral or immune-modulating therapies may be discussed in select cases, but treatment plans should always be individualized by a veterinarian.

Treat secondary infections promptly and completely
Plan regular veterinary exams, often every 6 months or as advised
Prioritize dental and oral care because gingivitis and stomatitis are common
Keep infected cats indoors to reduce exposure and lower transmission risk
Feed a balanced commercial diet and avoid raw diets unless your vet specifically advises otherwise
Use year-round parasite prevention and monitor for weight loss or behavior changes

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2.5–5%

Healthy cats infected in North America

15%+

Higher-risk or sick cats infected

1–5%

Average exposure rate reported by VCA

1–3 months

When acute signs may appear

Living with Feline Immunodeficiency Virus

Before

After

Before diagnosis: outdoor access, fighting risk, and delayed testing after a bite wound.

After diagnosis: keep your cat indoors, reduce stress, and call your vet after any illness or exposure.

Before diagnosis: mild bad breath or mouth pain may be easy to miss.

After diagnosis: watch closely for dental pain, drooling, weight loss, and changes in appetite because cats hide discomfort well.

Before diagnosis: routine care may happen only when your cat seems sick.

After diagnosis: schedule regular wellness exams and lab monitoring even if your cat appears normal.

Before diagnosis: bowls, litter boxes, and household stressors may not seem important.

After diagnosis: keep resources clean, provide enough litter boxes and feeding stations, and maintain a low-stress indoor environment.

Frequently Asked Questions

Is FIV in cats a death sentence?

No. Many FIV-positive cats can live for years with good care. Cornell notes that cats with FIV commonly live average life spans as long as they are otherwise well managed and not also infected with feline leukemia virus. Regular checkups and fast treatment of secondary infections are important.

Can humans or dogs catch FIV from a cat?

No. FIV is species-specific and infects cats, not people or dogs.

How do cats usually get FIV?

The most common route is a bite wound from an infected cat. That is why outdoor cats, intact males, and cats that fight are at highest risk.

Can FIV-positive cats live with other cats?

Sometimes, yes. In stable homes where cats do not fight, casual transmission risk appears low. However, other cats in the home should be tested, and your veterinarian can help you decide whether separation is needed based on behavior and household dynamics.

What should I do if my cat was bitten by another cat?

Call your vet. Your cat may need wound care and FIV testing now and again later, because early testing can miss recent infection before antibodies develop.

Is there a vaccine for FIV?

Cornell and current AAFP client guidance state there is no vaccine commercially available in North America. Prevention focuses on keeping cats indoors, reducing fighting, and testing at-risk cats.

Sources

Disclaimer: The information provided in this article is for educational purposes only and does not constitute veterinary medical advice. Reading this content does not establish a veterinarian-client-patient relationship. Every pet is different — always consult a licensed veterinarian before making decisions about your pet's health, diet, or care. If you'd like personalized guidance, you can talk to one of our vets. If your pet is experiencing a medical emergency, contact your local emergency animal hospital immediately.

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