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Feline Leukemia

July 15, 2023

Today is Feline Leukemia Day. This is one of the more serious kitty holidays on the calendar, but it is an important topic. Feline leukemia is much more common than any of us would like: it affects between two and three percent of our furry pals. A Brampton, ON vet goes over some basic facts about the disease below.

It Affects Fluffy’s Immunity

The FeLV virus compromises Fluffy’s immunity, leaving her very vulnerable to secondary infections, such as skin or respiratory problems. She’ll also be at higher risk of developing certain cancers. The disease can also significantly shorten her lifespan.

Risk Factors

There are several risk factors to keep in mind. Kittens born to FeLV-positive mommas are of course at greatest risk. Males are also more likely to be infected than females. Living with an infected cat also increases Fluffy’s odds. Outdoor cats are also at elevated risk, as are those in multi-cat homes.


Don’t worry: you can’t catch FeLV. However, it is quite contagious between kitties. Bites and scratches are common forms of transmission. However, Fluffy can also get it by sharing bowls or litterboxes with an infected cat.


The best way to protect your kitty from FeLV? Get her vaccinated! The vaccine is usually administered to kittens when they’re around two months old. Fluffy will also need boosters. Ask your vet for recommendations.


Some cats are able to fight the virus off, which will effectively render them immune to it. However, even if Fluffy is asymptomatic and purrfectly healthy, she could still transmit it to other cats.

Warning Signs

FeLV is typically asymptomatic at first. It doesn’t always progress at the same rate; however, symptoms can appear in just a few weeks. Some things to look for include lethargy, weight loss, respiratory issues, and fever. However, because it’s an immunity issue, this disease can present in many ways, such as through skin infections. Ask your vet for more information.


A FeLV-positive diagnosis isn’t good, but it isn’t the end of the world. Fluffy will need some extra TLC: you’ll need to be diligent about keeping her things clean and making sure she stays inside. FeLV-positive cats also need more frequent veterinary appointments. However, with good TLC,  your furry friend can still lead a wonderful life … or nine!

Our Advice on Feline Leukemia in 2024

What is Feline Leukemia, and how does it affect a cat’s health?

Feline Leukemia (FeLV) is a viral disease that impairs a cat’s immune system, making them more susceptible to infections, illnesses, and certain cancers. It can cause anemia and lymphoma, among other health issues. FeLV is one of cats’ most common infectious diseases and can significantly shorten their lifespan. The virus affects the cat’s bone marrow and blood, leading to secondary health complications. Early stages may show no symptoms, but as the disease progresses, it can manifest in weight loss, lethargy, respiratory problems, and more. Regular veterinary care is crucial for managing FeLV-positive cats.

How is Feline Leukemia transmitted among cats?

Feline Leukemia Virus (FeLV) is primarily transmitted among cats through close contact. Standard transmission methods include bite wounds, mutual grooming, and sharing food or water bowls and litter boxes with an infected cat. The virus can also be passed from a mother cat to her kittens during pregnancy or through nursing. FeLV is not typically airborne and requires direct contact with infected bodily fluids for transmission, such as saliva, blood, or urine. It’s important to note that FeLV is a cat-specific virus and does not spread to humans or other animal species.

What are the best preventative measures against FeLV for cats?

The best preventative measures against the Feline Leukemia Virus (FeLV) include vaccination and minimizing exposure risks. Vaccinate kittens and at-risk adult cats against FeLV, following a schedule recommended by your veterinarian. Feline Leukemia Virus (FeLV) is a contagious disease that affects cats worldwide. Kittens and young adults are more susceptible to the infection, so keeping them indoors is crucial to reduce exposure to infected cats. To prevent the transmission of FeLV, it’s essential to avoid introducing FeLV-positive cats into households with uninfected cats and to separate infected cats. By following these measures, we can help reduce the spread of this disease and keep our feline friends healthy. Regular veterinary check-ups and maintaining a clean, stress-free environment are crucial in avoiding FeLV.

What are the warning signs of FeLV in cats?

Warning signs of Feline Leukemia Virus (FeLV) in cats can vary but often include persistent lethargy, weight loss, poor coat condition, and recurring respiratory infections. Cats may also experience fever, diarrhea, and swollen lymph nodes. FeLV can lead to anemia, shown by pale gums and weakness, and increased susceptibility to other infections. Some cats exhibit behavioral changes or decreased appetite. Advanced stages can present with more severe symptoms like jaundice or difficulty breathing. Due to its impact on immunity, FeLV can cause diverse clinical signs, making regular veterinary check-ups crucial for early detection and management.

How does the progression and presentation of FeLV vary in cats?

The progression and presentation of Feline Leukemia Virus (FeLV) in cats can vary widely. Some cats may remain asymptomatic for years, while others develop symptoms relatively quickly. Early stages often show no signs, but as the disease progresses, symptoms like weight loss, lethargy, and recurrent infections become more evident. FeLV can lead to anemia, lymphoma, and other cancers, with symptoms depending on the affected organs. Some cats may experience acute illness, while others have chronic, slowly worsening conditions. The virus’s impact on the immune system means symptoms can manifest in multiple ways, making regular veterinary monitoring essential for managing FeLV-positive cats.

Do you have questions about FeLV? Contact us, your Brampton, ON pet hospital, today!