Feline Leukemia Virus
  • Catharina Hjorth

Feline Leukemia Virus


Most of us will know someone close to us who have suffered from one of the many forms of cancer, however what not everyone knows, is that cancer is also a disease that can affect our animals in large numbers. One of the most commonly seen ones in cats, is the Feline leukemia virus (FeLV).

Feline Leukemia Virus is an oncogenic, immunosuppressive retrovirus. Oncogenic retroviruses are only of veterinary relevance, however it is also retroviruses that causes HIV, leading to AIDS, in humans, which gives an idea of how dangerous this virus can be. In cats, if the immune system cannot defeat the virus, with time, it can cause anemia and can be lethal. Only second to trauma, FeVL is the leading cause of death in cats, killing 85% of persistently infested feline within 3 years of diagnosis. The main cause of death when infected with FeLV is anemia and lymphoma, but also the suppression of the immune system, which can lead the cats to be predisposed to other deadly infections. All caused by attracting a virus.

The Feline leukemia virus is specific to felines only; it cannot be transmitted to humans or other species of animals. The virus is passed from cat to cat via saliva, blood and other bodily fluids. The virus doesn’t survive long outside the body The virus infects hematopoietic precursor cells soon after the animal is infected, and continues to replicate here in hematopoietic and lymphatic tissue. Here it remains persistently viremic, meaning it can continuously infect other cats. However, one of the troubles with FeLV is that it can for a long period of time appear asymptomatic - meaning a lot of cats shows little to no symptoms for weeks and even up to several years.

The disease has a wide range of effects. The cat can fight off the infections and become a carrier that never gets sick, but can infect others, or it can become sick with a compromised immune system. Nonetheless the development of lymphomas is considered the final stage of the disease, it is here the symptoms will most often appear, and owners will become aware of it. The most common symptoms are weight loss, fatigue, fever, poor coat condition and everything from anisocoria (uneven pupils) to skin lesions.

Because the symptoms are so varied, and can even be non-existing, the easiest way to test for Feline Leukemia Virus, is to do a blood test called ELISA.

ELISA tests for antibodies for a specific virus in the blood. The test is highly sensitive, meaning it will rarely misdiagnose sick animals as being healthy. If the ELISA test is positive, it is often followed up by a IFA test to determine what stage of the disease the cat is in. This is important, as help started early gives the cats a better chance for prolonged survival.

However, there is no cure for Feline Leukemia Virus. Nonetheless, the cat can be helped to prolong a healthy existence by trying to limit the chance of getting into contacts with infections, this includes keeping the cat indoor from there on. This however, can be an issue for some cats. From a veterinarians point FeLV can be treated individually, depending on the symptoms the infected cat is showing, and secondary infections may be treated with antibiotics and/or anti-inflammatory drugs if necessary. It is important to note as well, that some cats can clear the infections themselves. Sadly though, the reality is, that by the time the cat is showing symptoms, the outlook is likely to be poor, and some cats will be euthanized as they have a poor quality of life.

Due to the poor outlook, many cat owners will often ask if it could have been prevented. One could argue that keeping the cat indoor, and thereby away from other cats, diminishes the chance of being infected significantly. However, I personally believe cats should be allowed to roam outside if possible. I find that the cats I meet, are happier when allowed to hunt and explore.

Other options includes a vaccine that is available most places; protection can't be guaranteed fully, but it is still important to make sure the cats receive annual boosters to try and keep the virus down in an area.

This is also why preventive measures are so important. In many areas the FeLV in the population is reduced, but exactly because of this, it's important to have cats checked for FeLV to ensure it continues this way - thereby preventing healthy cats from contracting the disease.

So if you are a cat owner who worries your cat may have contracted the virus, please take it to the nearest qualified veterinarian to be checked. Not only could this mean a longer, healthier life for your cat - it could save the lives of others, and help ensuring our cats have a long and healthy life.