Feline Leukaemia Virus – FeLV

Feline Leukaemia Virus, FeLV Test Kit

Feline Leukaemia Virus, FeLV Test Kit

Feline Leukaemia Virus – FeLV, has long been a killer of cats, but thankfully, there is now a vaccine available which offers good protection against its effects. This is important because cats that are infected with feline leukaemia are a particular threat to the health of unvaccinated felines in the neighbourhood. Although the virus can be confirmed easily by means of a blood test, the symptoms associated with it can be overlooked in the early stages.

Why should my cat’s anaemia be linked with an FeLV infection? FeLV attacks the bone marrow where red blood cells are produced and so lessens the number in circulation. It can also destroy those already in the bloodstream, resulting in anaemia.

My cat has FeLV, but he was vaccinated. What has happened? The most likely explanation is that your cat was already infected with FeLV prior to being vaccinated. Some vets will test cats for the virus prior to vaccination.

What should I do with my cat now he is positive for FeLV? Keep him in strict isolation, as he represents a danger to other cats. Sadly, a second positive test means that he is almost certainly going to die. Unfortunately, there is no treatment available. Thankfully however, not all cats that are infected by FeLV actually go on to develop the disease itself.

If a cat gives a positive blood test, confirming the presence of the virus in its body, then it should be tested again about three months later. By this stage, it is possible that the body’s immune system will have overcome the virus, eliminating it before it can cause any lasting harm.

In spite of its name, FeLV’s main effects are on the lymphoid tissue rather than the blood, causing malignant tumours known as lymphosarcomas.

Feline Leukaemia Virus – FeLV – Symptoms to Look For

FeLV may cause a range of symptoms, depending on which part of the body is affected. Young cats, and especially Siamese may suffer tumours of the thymus, which is located at the front of the chest, and these will cause difficulty in breathing. Another common site for lymphosarcomas is the intestinal tract, with recurrent bouts of diarrhoea being the most likely indicator of their presence here.


The secondary effect of these growths is that as the lymphoid tissue forms a vital link as part of the body’s immune response, so the body’s ability to fight off infections is reduced. Cats suffering from FeLV often develop relatively minor ailments such as inflammation of the gums (gingivitis) which they cannot shake off easily.

  • If your cat has died from FeLV, and you feel ready to acquire another cat, you must allow at least a month before getting one. It is better to acquire a cat that has been immunised against the virus. Also disinfect all equipment that is not being replaced.
  • Extensive tests have shown that FeLV cannot be passed to humans, so if your cat falls ill, the virus is not likely to spread to other members of the family.
  • In the case of pregnant cats, FeLV can cause abortion, and may be a cause of so-called `fading kittens’, which die at an early age.
  • Abyssinians used to be thought to be most susceptible to the infection, but any cat is vulnerable. The infection has even been identified in lions.