Feline Leukemia Virus (FeLV) in Cats

A serene tabby cat with FeLV peacefully rests on a cozy blanket.

What Cat Owners Need to Know

Feline Leukemia Virus, or FeLV, is one of the most important infectious diseases in cats. It can affect a cat’s immune system, increase the risk of certain cancers, and make affected cats more vulnerable to other illnesses.

A diagnosis of FeLV is not automatically a poor outcome. Some FeLV-positive cats can live comfortably for years, especially with good veterinary care, low stress, and an indoor lifestyle.

What Is FeLV?

A Viral Infection That Affects the Whole Body

FeLV is a retrovirus that can interfere with normal immune function and may also contribute to blood disorders and cancer in cats.

Not every cat with FeLV becomes seriously ill straight away. Some cats remain well for long periods, while others develop health problems sooner.

How Cats Become Infected

FeLV Spreads Mostly Through Close Cat-to-Cat Contact

FeLV is spread between cats most commonly through close contact with infected cats, especially through saliva and other secretions. It can spread through grooming, shared bowls, close social contact, and bite wounds, and can also be passed from an infected mother cat to her kittens.

Cats most at risk include:

• kittens

• outdoor cats

• cats living with infected cats

• cats with unknown vaccination or testing history

Kittens are generally more susceptible than adult cats.

Signs of FeLV in Cats

Symptoms Can Be Vague at First

FeLV can cause a wide variety of signs, and in the early stages some cats may appear completely normal. Over time, affected cats may develop:

• weight loss

• poor appetite

• lethargy

• pale gums

• recurring infections

• fever

• enlarged lymph nodes

Because FeLV affects the immune system, infected cats may also be more likely to develop secondary or opportunistic infections.

How Veterinarians Diagnose FeLV

Screening and Confirmatory Testing

FeLV is usually first identified using a screening blood test. If that test is positive, your veterinarian may recommend confirmatory testing, because the stage of infection can affect results and interpretation.

Testing is especially recommended for:

• all new kittens

• newly adopted cats

• sick cats

• cats entering a household with other cats

• cats before their first FeLV vaccination

These are standard testing recommendations in feline specialist guidance.

Special Considerations for Kittens

A Positive Test in a Young Kitten May Need Rechecking

Very young kittens can sometimes test positive because of maternal factors or early exposure, so follow-up testing may be needed depending on age and risk. Your veterinarian will advise the correct timing for retesting.

Caring for a Cat With FeLV

Good Management Makes a Big Difference

Cats with FeLV generally do best when kept indoors only. This helps reduce exposure to infections and prevents spread of the virus to other cats.

Good care for a FeLV-positive cat usually includes:

• regular veterinary check-ups

• prompt treatment of any illness

• good nutrition

• parasite prevention

• stress reduction

• an indoor lifestyle

Cats with FeLV are often advised to have veterinary examinations at least every 6 months.

Can FeLV Be Treated?

There Is No Cure, But Supportive Care Helps

There is no cure that eliminates FeLV, but many cats benefit from supportive care and treatment of secondary illnesses as they arise. Management focuses on maintaining quality of life and treating problems early.

Preventing FeLV

Testing and Vaccination Are Important

Prevention involves:

• testing cats before introducing them to other cats

• reducing exposure to infected cats

• vaccinating at-risk cats

Current feline vaccination guidance considers FeLV vaccination a core vaccine for cats younger than 1 year old, and a non-core vaccine for older cats based on risk of exposure.

FeLV Care in Kalamunda

If your cat has tested positive for FeLV, or if you are adopting a new cat and want testing advice, the team at Hilltop Veterinary Hospital in Kalamunda can help guide you through diagnosis, monitoring, and long-term care.

Early testing and good ongoing management can make a significant difference to your cat’s health and quality of life.

Concerned About Your Cat’s Health?

If your cat is unwell, losing weight, or you would like FeLV testing before introducing a new cat to your home, book a consultation with Hilltop Veterinary Hospital so our veterinary team can assess your cat and recommend the most appropriate next steps.

Explore More Pet Health Advice

For more veterinary advice on common cat health problems, explore our Pet Health Advice library.

You can also browse our Cat Health Care articles to learn more about FIV, kidney disease, hyperthyroidism, vomiting, and other common feline medical conditions.

The information provided in this article is intended for educational purposes only and should not replace professional veterinary advice. Every cat’s medical situation is unique. If your cat is showing signs of illness or you have concerns about FeLV exposure, consult your veterinarian for proper diagnosis and treatment.