FIV and FeLV in Cats: What Owners Need to Know

At a glance

What it is	Two separate viral infections (feline immunodeficiency virus and feline leukaemia virus) that affect the immune system
Who's at risk	Cats that go outdoors, unneutered males that fight, cats living with an infected cat, and kittens born to an infected mother
Main signs	Often none at first; later, repeated infections, sore gums, weight loss, poor coat, lethargy and slow healing
Contagious?	Yes, between cats only. Neither virus can pass to people, dogs or other pets
Can it be prevented?	Risk can be reduced through neutering, testing, keeping positive cats apart from others and, for FeLV, vaccination discussed with your vet

What it is

FIV and FeLV are often mentioned together because they share a few features. Both are viruses, both affect the immune system, and both can be picked up by a simple blood test at the vet. Beyond that, they behave quite differently, and it helps to think of them as two separate conditions.

FIV (feline immunodeficiency virus) belongs to the same broad family as HIV in people, but it only infects cats. It slowly weakens the immune system over a long period. The virus is found mainly in saliva and is passed on most often through deep bite wounds, which is why it is seen more in cats that fight, especially unneutered males who roam and defend territory. Casual contact, such as sharing a bowl or grooming each other, is much less likely to spread FIV in a settled household where cats do not fight.

FeLV (feline leukaemia virus) spreads more easily. It is present in saliva, nasal secretions and other body fluids, so it can pass between cats through friendly, everyday contact: mutual grooming, sharing food and water bowls, and sharing litter trays. An infected mother can also pass it to her kittens before or after birth. Some cats exposed to FeLV fight off the virus, some carry it quietly, and some develop a lasting infection. A lasting infection is generally more serious than FIV, because FeLV can affect the bone marrow, the immune system and, in some cats, lead to certain cancers.

Neither virus can infect people, dogs, rabbits or other non-feline pets.

Signs to watch for

One of the most important things to understand is that a cat with FIV or FeLV can look completely well, sometimes for years. Many infections are only found through testing. When signs do appear, they tend to be vague and are usually caused by the illnesses that a weakened immune system lets in, rather than by the virus itself.

Signs that might be linked include:

• Infections that keep coming back or take a long time to clear, such as snuffles, skin problems or stomach upsets
• Red, sore or inflamed gums and mouth, which can make eating uncomfortable
• Gradual weight loss or a poor appetite
• A dull, scruffy or unkempt coat
• Low energy or sleeping more than usual
• Wounds that are slow to heal
• Swollen glands under the jaw or elsewhere
• Pale gums, which can be a sign of anaemia, particularly with FeLV
• Eye changes or a fever

These signs are not specific. Many other conditions can cause them, and a cat showing one or two of them is far more likely to have something else. Our symptom checker can help you think through what you are seeing, but only a vet can tell you what is going on.

When to see a vet

Book a routine appointment if:

• You have a new cat or kitten whose status is unknown, especially before introducing them to other cats
• Your cat has been in a fight and has a bite wound or abscess
• You notice gradual changes such as weight loss, a poorer coat or repeated minor infections
• You are thinking of adopting a second cat and want to know whether it is safe to mix them

Contact a vet promptly, the same day if possible, if your cat:

• Stops eating for more than a day
• Has very pale or yellow-tinged gums
• Seems weak, very quiet or is hiding
• Has difficulty breathing, a high temperature or a swelling that is growing

If your cat is already known to be FIV or FeLV positive, it is sensible to have a lower threshold for calling the vet, since their body may struggle to fight off infections that another cat would shrug off.

How vets diagnose it

Diagnosis usually starts with a quick blood test that can often be run in the practice. Many of these tests check for both viruses at once. A positive result is not always the end of the story, though, and your vet may recommend further steps.

• Confirming a result. Screening tests are very useful, but positive results, especially in a healthy cat with no risk factors, are often checked with a different laboratory test.
• Timing matters. A cat recently exposed to either virus may not test positive straight away. Your vet may suggest repeating the test after a period of time.
• Kittens and FIV. Young kittens can test positive for FIV because they have picked up protective antibodies from their mother, not because they are infected. Retesting when they are older often gives a clearer answer.
• FeLV can change. Some cats that test positive for FeLV later clear the virus, so a repeat test may be advised.

Your vet will also examine your cat and may suggest other checks, such as general blood tests, to understand how well they are coping overall.

Treatment and management

There is no cure that removes either virus from the body, but that does not mean nothing can be done. Management focuses on keeping your cat as healthy as possible and catching problems early.

Good care often includes:

• Regular check-ups, often more frequently than for other cats, so your vet can spot changes in weight, gums, eyes and lymph nodes early
• Prompt treatment of infections, because even minor illnesses deserve attention when the immune system is under strain
• A good-quality, complete diet and steady weight. Raw food is usually avoided for these cats because of the extra risk of infection
• Routine parasite control, including fleas and worms, as advised by your vet
• Dental care, since mouth problems are common. Our article on dental disease in pets explains what to look out for
• A calm, low-stress home, as stress can affect general health

Your vet may discuss specific treatments for particular problems as they come up. They will tailor any plan to your cat, so it is best to talk through your questions with them rather than trying anything on your own.

Prevention

You cannot control everything, but you can reduce the risk considerably.

• Neutering. Neutered cats, especially males, tend to roam less and fight less, which lowers the chance of bite wounds and FIV.
• Testing new cats. Before bringing a new cat into a household with others, ask your vet about testing. This is particularly important for FeLV.
• Vaccination for FeLV. A vaccine is available for FeLV. Whether it is right for your cat depends on their lifestyle, age and whether they go outdoors or mix with other cats. This is a conversation to have with your vet. There is no widely used FIV vaccine in many countries, so prevention relies on other measures.
• Keeping positive cats indoors. An FIV-positive or FeLV-positive cat kept indoors, or in a secure garden enclosure, is less likely to pass the virus to other cats and less likely to pick up infections themselves.
• Separate bowls and trays. In homes with an FeLV-positive cat and negative cats, your vet may suggest keeping them apart and not sharing bowls, beds or litter trays.
• Prompt care for bite wounds. Getting fight wounds checked helps prevent abscesses and gives you a chance to discuss testing.

Living with it

Hearing that your cat has FIV or FeLV can be upsetting, but try not to assume the worst. Many FIV-positive cats live long, happy lives with very few problems, often reaching a good age with thoughtful care. FeLV is more serious and some cats do become unwell sooner, but every cat is different, and many enjoy good-quality time with their families.

A few things can help day to day:

• Keep a simple diary of weight, appetite and energy so small changes are easier to notice
• Keep up with check-ups even when your cat seems well
• Make the home comfortable and enriching, especially for a cat who has moved indoors, with climbing spaces, play and window views
• Talk to your vet openly about what to expect and when to get in touch

If you share your home with other cats, your vet can help you decide how to keep everyone safe and content. With good information and regular support from your vet, living with a positive cat is usually very manageable.