Ginger cat
© Pixabay

Everything you need to know about feline leukaemia virus

By Dawn Parrish Content Writer

Updated on the

Feline Leukaemia Virus is a terrible disease that affects the cat’s immune system. Otherwise known as FeLV, this health condition can make the kitty vulnerable to other health issues such as tumours or anaemia.

What is Feline Leukaemia Virus?

First of all, the Feline Leukaemia Virus is a tiny micro-organism that consists of glycoproteins, proteins and nucleic acid. This highly infectious virus is only specific to members of the feline family and cannot infect humans or other animals. However, during the last 25 years with the development of medical research and an effective vaccine, the prevalence of the disease has decreased.

A cat infected with this FeLV virus is more at risk of developing a life-threatening anaemia condition. Likewise, other serious health problems linked to feline leukaemia virus are:

  • abortion in pregnant cats # intestinal inflammation – severe enteritis
  • neurological or nerve issues
  • ocular (eye) disease

You can make sure that your kitty is vaccinated against this FeLV virus. Certainly, in recent years, the feline population has reported fewer incidences of the disease, probably achieved through annual boosters.

Causes of Feline Leukaemia Virus

Infected cats carry this FeLV virus in their saliva, urine, faeces, blood and tears. A kitten can very easily pick up this virus from their mothers. Similarly, close contact when cats groom, feed or drink together can cause a transfer of the virus. It’s not thought to be transferred by fighting. Once the virus leaves the cat’s body, it cannot survive. It is thought to be easily destroyed with water and detergent shampoo or soap.

To prevent feline leukaemia virus transmission dont feed your cats out of the same dish ©Pixabay

The Virus

Feline leukaemia virus (FeLV) is a gamma-retrovirus affecting domestic cats worldwide; it was first detected in 1964 by electron microscopy (Fig. 1), after experimental transmission of cell-free material (Jarrett et al., 1964). FeLV also infects small wild cats including Felis silvestris  and European and Iberian lynxes, Florida Panthers, the Chilean wildcat (Leopardus guigna) and Jaguarundis (Puma yagouaroundi) of Central and South America (Leutenegger et al., 1999; Cunningham et al., 2008; Meli et al., 2009; Filoni et al., 2012; Mora et al., 2015; Silva et al., 2016).

The feline leukaemia guidelines were published in J Feline Med Surg 2009 -Report by

Symptoms of Feline Leukaemia

There are many ways that this disease affects a cat’s body. In the first place, this most common feline cancer can lead to many blood disorders. Likewise, this can cause an immune deficiency that allows the cat to have other infections. Because of this, severe illness can result from infection with bacteria, fungi, protozoa and viruses. It is these secondary infections that give rise to the many health conditions associated with feline leukaemia virus.

In the initial stages, your cat may show no symptoms at all. The incubation period can be quite lengthy. However, over time, even months or years, her health can deteriorate. Her illness may repeat in cycles of ill-health and then appearing to be fine. She may have a high temperature and be out of sorts.

Look out for the following visible signs that your cat might have feline leukaemia virus:

  • respiratory problems
  • sore gums 
  • digestive issues
  • enlarged lymph nodes
  • severe anaemia
  • breeding issues

If a cat is exposed to the Feline Leukaemia Virus, one of these following things might happen:

No 1. Transient infection and subsequent immunity

The cat can suffer from a transient viral illness, defend off the virus and go on to acquire future immunity.  Research shows that up to 80% of cats that initially have the FeLV recuperate and are then immune from the virus. However, young kittens under 4 months old are not likely to fend off this virus exposure.

No 2. Continuous infection and disease

If the infection is quite persistent and not overpowered, the cat will have the virus permanently. This virus infection will eventually compromise the cat’s immune responses and move to the bone marrow. Certainly, your cat may appear to be without symptoms for several years. However, within a 2-3 year period, other diseases related to the feline leukaemia virus will develop.

Although humans can be exposed routinely to the feline leukemia virus by contact with an infected cat, it is not possible for them to become infected at all.

No 3. Dormant infection and immunity

Should your kitty be constantly infected, there is no definitive proof that she will develop any disease. Although she may have the virus in her body, the cat can produce an effective immunity to the virus. This results in a dormant, or latent carrier. Consequently, a cat with no definite virus may still be a carrier and transmit to another feline. This dormancy of the virus in some cats appears in many cases to be only temporary. Many cats can become free of the virus even several years after the first infection.

A blood test is the only definitive way to diagnose feline leukaemia virus ©Pixabay

Diagnosis of Feline Leukaemia Virus

In the first place, speak to a medical professional. A blood test will be taken that can confirm the virus is present in the blood. If no definite confirmation of the virus, a second test can be taken a few weeks after the first.

Treatment for FeLV

Once a diagnosis has taken place, you will wonder what the next step is. Unfortunately, at present, there is no treatment to eradicate the feline leukaemia virus in cats. Your cat will, of course, be given appropriate treatment for any other associated illnesses or health problems, arising from the virus. Sadly, the prognosis isn’t too good.

If your cat is known to be infected, house confinement is needed. Make sure their vaccination programme is up to date to prevent any further infections. If your cat has a poor quality of life because of the disease, you may have to make the decision to opt for euthanasia. Because FeLV is such an infection disease, other cats are at high risk of developing the condition too. it is important to have all other felines in the household tested. If possible, the ideal solution is to separate non-infected cats and those cats with the infection, to prevent the further transmission of feline leukaemia virus.

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