Feline leukaemia (FeLV) & Feline Immunodeficiency Virus (FIV)

Feline Leukaemia Virus (FeLV) and Feline Immunodeficiency Virus (FIV) are serious, incurable viruses which affect the immune function of cats. They’re similar to HIV/AIDS in people.
Both diseases affect the immune system so that normal problems, like parasites, snuffles, etc. take a much heavier toll on the cat than they would on healthy cats, and make it easier for cancers to proliferate. Although both have similar signs and symptoms in many ways, FeLV is considered to be more devastating than FIV.

Although your cat may look healthy, he or she could still have one or both of these viruses as they usually do not show up immediately. Similar to AIDS in humans, the infected cat may be fine for a long time and then start to get sick and eventually die if not treated. 


Can I catch these illnesses? What about my children? And my dog?
No, absolutely not. ONLY cats can get the illnesses. There is NO WAY people or any other animals, including dogs, chickens, goats, etc. can get them.

How can my cat be infected?
FIV & FeLV are transmitted in similar ways, mainly during fighting and mating (bearing in mind that cats tend to bite during mating). Please do not chase away or harm other cats in order to try and keep your own cat safe – rather keep your own cat safe indoors.

FeLV: This virus is shed in saliva, urine, faeces, nasal secretions, and milk. It is most often spread through fighting and mating, grooming, and from mother cats to their kittens either in utero or while nursing. It may also, rarely, be transmitted via shared litter boxes, and shared food and water bowls.

FIV: The virus is mainly transmitted via saliva but also blood (e.g. transfusions). The main way of spreading it is through bite wounds, which would be during fighting or mating. It is thought to be unlikely that it’s transmitted in food/water bowls or litter boxes or via grooming. Infected mother cats can give it to their kittens in utero, especially if they’re infected when already pregnant.

What can I do to prevent it?
Have your cat sterilised by 6 months old as unsterilised cats wander around, are in contact with many more cats, mate, and fight. Cats seem to be going into season earlier and earlier, and we are coming across cats as young as 3 months that are ready to start having kittens. Many vets will sterilise kittens at 10 – 12 weeks of age already, as a result. We recommend that you not wait longer than 6 months. All kittens adopted from FAW will be sterilised by 6 months of age, as included in your adoption fee.

Keep your cat indoors instead of letting them roam.

There is a vaccine for Feline leukaemia but it is expensive and not 100% effective; there is also evidence that, in some cases, it could contribute to feline injection-site sarcoma (a type of malignant cancer). There is no effective vaccine for Feline Immunodeficiency Virus.

How do I know if my cat has FIV or FeLV?
There’s only one way to know for sure: a blood test that your vet can administer. It is advised to retest after 60 days to be sure. The test takes around 10 minutes and will require a drop of blood taken from your cat. 

In the beginning, your cat might not have any symptoms – some stay symptom free for years and, in a few cases, never show symptoms at all but may still pass on the virus/es to other cats. Some cats will have mild signs of infection a few weeks after they’re first infected, which gets better and they may then seem healthy for months or even years.

Both may result in fevers, swollen lymph nodes, weight loss, not wanting to eat, slow healing from injuries, frequent sicknesses, fatigue, depression, diarrhoea, skin sores, mouth and gum inflammation, chronic conjunctivitis, and poor coat condition. There other treatable illness with similar symptoms, such as thyroid imbalance or snuffles, so do not assume your cat has one of these viruses and panic. If in doubt, take your feline friend to the vet.

FeLV: Aside from the above, FeLV causes cancers by promoting cancerous cell mutations and by suppressing the immune system’s ability to heal. Leukaemia and lymphomas are common. Anaemia (reduction in red blood cells and/or haemoglobin), pancytopaenia (reduction in platelets, and red and white blood cells), and bone marrow suppression are also common.

FIV: Cats have suppression of white blood cells which means the immune system is progressively destroyed. This means that, aside from the abovementioned, you’ll see signs and symptoms related to a suppressed immune system such as upper respiratory infections, pneumonia, seizures and behavioural changes. Cancers, particularly lymphoma and squamous cell carcinoma, occur in many FIV-positive cats

Are FIV and FeLV curable?
Unfortunately, at this time, there is no cure for either of these diseases. The only options are keeping your cat healthy through good-quality food, a low-stress life, supplements, etc. and supportive treatment for secondary illnesses. If looked after properly, your cat could live for many years with one of these viruses (see below). 

Can’t I just leave my cat to live with it?
No, you cannot just leave them to live with it as they can suffer terribly. It may be kinder to put him or her to sleep, both to prevent the cat from suffering and to prevent the disease from spreading to other cats. Feral cats or cats living in non-optimal homes are usually put to sleep because, without a human to care for them properly, they will suffer greatly and experience a terrible, slow death.

It is possible to keep a cat with one or both of these viruses BUT you will need to put in a lot of work and money.

  • In order to protect other cats, your positive cat must become an indoor cat so that they can’t roam and infect others.
  • If you have other cats which are negative for both these viruses, you’ll need to keep the positive cat away from them OR accept that they may catch it from the positive cat. Assuming your cats don’t fight, FIV is less easily passed on than FeLV.
  • Positive cats need the best quality food (and, possibly, supplements) in order to keep their immune systems healthy.
  • You must keep their stress levels low.
  • They need regular vet checks (every 6 months is recommended).
  • Be very careful not to bring other illnesses to your cat, for example, feline herpesvirus that causes snuffles can live on surfaces for several months. You may need to invest in veterinary disinfectant and use this before handling your positive cat. Some owners of positive cats leave their shoes outside so as not to carry things into the house that could make their cat ill, like giardia, coccidiosis, etc.
  • Parasites can kill FIV- or FeLV-positive cats so you need to ensure they’re dewormed, kept flea and tick free, etc.
  • Any signs of infection must be treated immediately because it is often secondary infections that kills FIV- or FeLV-positive cats. Once they get sick with one thing, their weakened immune systems may succumb to more and worse infections.

The bottom line is this: you need to be prepared to put in the funds and effort for the rest of their lives and, if you cannot commit to this, putting them to sleep is usually kinder. This is also generally the best option for feral cats as they will not have access to the same veterinary care as owned cats, and they can infect other cats too. 

Note that FIV tends to be much slower progressing than FeLV but, once a cat infected with either virus starts getting sick (showing symptoms), they usually only have a few months left at most. A cat infected with both viruses tends to have a greatly shortened lifespan.

If I had a cat in the house that had one or both of these illnesses, can I get another cat afterwards?
The viruses don’t live long outside the body so, when the infected cat is no longer in your house (and any other cats you have test negative after 6 months), you can get another cat. You will need to clean all bowls, litter boxes, etc. thoroughly just in case. Remember to have your new cat sterilised by 6 months.

Does FAW rehome positive cats?
No, we do not. Cats surrendered to FAW or found as strays are tested for both viruses. Should they test positive, they are humanely put to sleep by a veterinarian. The reasons for this are as follows:

  • Our mission is to prevent suffering of animals now and in future. We can’t contribute to possible spread of deadly viruses by rehoming contagious cats as this would be irresponsible and go against our aims.
  • FAW only uses foster homes and we cannot expose people’s own cats to contagious illnesses.
  • Some of the cats that find their way to us, be they strays, surrendered, or rescued/confiscated may have a sub-optimal history such as poor nutrition, stress, parasites, injuries, etc. The key to keeping a cat with FIV or FeLV is swift, effective, intensive treatment but, because the cat may have been in bad circumstances for some time, it may be too late and the virus is already active and flaring up. As we don’t always know the history, we can’t take the chance.
  • The above will be worsened because of the immense stress of being brought in to the clinic, examined, transported, moved to fosters, changes in food, etc. This amount of stress will affect the immune system, causing the virus to worsen and the cat to become sick. We would then have an ill, homeless cat on our hands requiring extensive treatment (which may not even be successful), putting it through a great deal or stress without it even having a loving home to go to. This would be cruel.

As you can see in the above section ‘Can I leave my cat to live with it?’, looking after a positive cat is intensive and expensive, which is why most animal welfares aren’t able to keep or rehome them.

So, for the sake of both that specific cat and other cats, FAW took the difficult decision to humanely put positive cats to sleep and only rehome healthy cats. Fortunately, because most animal welfares follow the same protocol, we are seeing the numbers of infected cats reduce in our area of operation.

It is unlikely that these diseases will ever disappear entirely but we can try to reduce how many cats are infected.

© Copyright reserved Jennifer Davies 2021

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