Feline Leukemia Virus is a retrovirus found only in cats. It is considered a serious condition which, under some circumstances, can significantly shorten a cat’s lifespan.
What is FeLV?
Feline Leukemia Virus, also known as FeLV, was discovered in 1964. This virus can have a wide range of effects on infected cats.
Firstly, cats suffering from FeLV frequently develop cancerous tumours, which can impact quality of life and longevity. As the name also suggests, however, it can also have a serious impact on the immune system. It has been estimated that 50% of all FeLV-related diseases are due to immunosuppression.
Cats with compromised immune systems are far more at risk of secondary infections, and can much of their time fighting off one bug or another.
A further quarter of infected cats suffer from anaemia. Sadly, once is showing signs there is no known cure, and vets estimate that around 80% of cats die within 3-4 years of diagnosis.
What are the Symptoms of FeLV?
FeLV is an interesting disease in that the symptoms can vary significantly between patients. The most common early symptoms are fever, loss of appetite and lethargy.
What is notable is that FeLV goes through a number of stages of infection. In the first stage, the virus persist within the blood stream of the cat. Here the symptoms observed are likely to be mild. Numerous cases exist where a cat’s immune system has succeeded in beating these early infections. Indeed, young kittens may inherit immunity from their mothers while nursing.
In the second stage, however, the virus moves on to infect other organs of the body, such as the bone marrow. Once this stage takes hold there is rarely anything that can be done.
How is FeLV Caught?
The FeLV virus tends not to survive long outside of the body. It has been estimated that the virus is only capable of living for a couple of hours when not present in a host.
Infections most commonly occur, therefore, as a result of direct contact with infected cats. One of the most common sources of infection is believed to be fights with other cats, where the virus is passed on thanks to bite or claw wounds.
The virus is, however, present in most bodily fluids of infected cats. Thus it has been found in the saliva, faeces, urine and milk. In this way infected mothers are capable of passing it on to their youngsters, while cats sharing litter trays and food bowls also have the potential to infect one another.
What Cats are Most at Risk of FeLV?
In truth, FeLV can affect cats of any type. However, it is believed that cats living a primarily outdoor lifestyle are at particular risk. Additionally, cats with naturally supressed immune systems – such as the very young or old, or those recovering from illness, may be at particular risk. At present it is estimated that between 1 and 3% of cats in the UK and USA suffer from the virus, so there is a significant risk of cats getting infected.
Diagnosis and Treatment
There are a number of blood tests which can indicate the existence of FeLV.
Most common of these is an ELISA test, while immunochromatography is increasingly popular. Whatever the test used, it is important to appreciate that false positives and negatives are both encountered on a regular basis.
As a result, most vets will request to take multiple samples over an extended period of time to be certain of the diagnosis.
As discussed, the prognosis is often disappointing.
While some cats will manage to beat the initial infection, they may well still go through life as carriers without showing any symptoms.
In more severe cases there is little that can be done to fight the infection.
All cats known to be infected should be confined indoors to prevent them infecting other cats in the neighbourhood. They should also be kept away from other cats that you own to add further protection.
While a number of vaccines do exist, none offer 100% protection at present. Worse, FeLV vaccinations can have a number of unpleasant side-effects, such as causing tumours to grow at the vaccination site, so many vets are loathe to vaccinate unless absolutely necessary.