Feline Leukaemia: Causes, Symptoms and Treatment

Feline Leukaemia is one of the most common infectious diseases found in cats. As the second-leading cause of death in cats, it’s responsible for up to 85% of deaths in infected felines within three years of diagnosis.

However, exposure to the Feline Leukaemia virus, or FeLV, doesn’t have to be a death sentence; about 70% of cats that encounter the virus are able to resist or eliminate infection without human assistance. And, thanks to effective vaccines and accurate testing methods, the prevalence of FeLV has decreased significantly over the past 25 years. 

Symptoms and Transmission

Feline leukaemia only affects cats – it can’t be transmitted to people, dogs, or other animals. It’s passed from an infected cat through saliva, blood, urine, and faeces, and in utero in kittens or from an infected mother’s milk. Although the virus doesn’t live long outside a cat’s body, grooming and fighting are typical ways for infection to spread. 

The disease is often spread by seemingly ‘healthy’ cats; even a cat that doesn’t appear to be sick may be infected and able to transmit the virus, which is why vaccinating your cat annually is the best form of prevention. Although symptoms may vary, the virus commonly results in anemia or lymphoma, or predisposed illnesses that result from a suppressed immune system.

Some cats infected with FeLV are asymptomatic, which means they show no symptoms at all. If symptoms do appear, they can be in almost any form. A lack of appetite, lethargy, fever, and weight loss are common (but not guaranteed), which is why a blood test is the only sure way to tell if your cat is infected. These screening tests need only a few drops of blood and can be performed in a matter of minutes. If the screening test is positive, your veterinarian will recommend further blood tests and a treatment plan.

Diagnosis and Treatment

Two types of blood tests are commonly used to diagnose FeLV: an enzyme-linked immunosorbent assay (ELISA), which is usually performed upfront by your veterinarian as a screening tool to detect the presence of free FeLV particles in the bloodstream; and a laboratory test called the IFA, which detects the progressive phase of the infection. Sadly, cats that are IFA-positive have a poor long-term prognosis.

Although there is presently no cure for FeLV infection, secondary infections can be treated as they appear. However, the prognosis is dire for cats showing bone marrow compromise or widespread lymphoma. It is important to note that no matter the stage of infection, an FeLV-positive cat must be kept indoors and neutered to avoid spreading the virus.

How Can I Prevent My Cat From Getting Feline Leukaemia?

Your cat is at a higher risk of contracting FeLV if it is exposed to infected cats, especially if it is a kitten or young adult. Older cats are less likely to contract the infection because resistance seems to increase with age. A vaccination is available that provides protection against the virus, however it’s not a core vaccine and is only recommended for cats whose lifestyle puts them at risk for infection (those who go outside or live in shelters or catteries). Cats that live indoors and are not exposed to other cats are not at risk for infection. That said, most veterinarians recommend vaccinating kittens against FeLV regardless of lifestyle because of their susceptibility to infection.

Lisa Wallace

Freelance Writer & EditorI’m a Cape Town-based writer working in education technology. I love people, but undoubtedly love felines more! I literally skip with glee when TEARS rope me in with a writing assignment – it’s a great pleasure to be able to use my craft to help their marketing team, in any small way I can.