As a cat parent, you want your cat to have a happy and healthy life for as long as possible. Unfortunately, feline diseases exist that can significantly impact your cat’s lifespan. Feline leukemia is one of those diseases. However, there are ways to help protect cats from this contagious and often fatal virus.
What Is Feline Leukemia Virus (FeLV)?
Although vaccines and testing have reduced its incidence, feline leukemia virus is still one of the most common infectious diseases in cats — particularly in cats who spend time outdoors fraternizing with local neighborhood cats of unknown FeLV status.
There are three possible outcomes when a cat is infected with FeLV. For roughly one-third of cats, their immune system will eliminate the virus and their white blood cells will develop antibodies, providing immunity against FeLV.
Around another one-third of cats will develop a partial immune response that prevents the virus from replicating. While the virus is inactive, these cats can’t infect other cats, and it’s unlikely that they will develop symptoms. However, it is possible for the virus to reactivate if the cat’s immune system is suppressed, which means they can spread the disease and become sick.
For the last 30–40 percent of cats, their immune system is unable to eliminate the virus, which allows the virus to continually replicate and spread throughout their lymph nodes, bone marrow and organs. Cats persistently infected with FeLV can infect other cats and are at the highest risk of developing secondary infections and diseases that are eventually fatal.
Is Feline Leukemia Virus Contagious?
Yes, transmission of feline leukemia virus most commonly occurs through close social contact between cats. The virus is shed in the saliva and nasal secretions of an infected cat, as well as in their bodily fluids (feces, urine and milk). This means that affected cats who share feed and water bowls and use the same litter box as other cats can spread the disease. FeLV can also be spread by mutual grooming, through bite wounds, during mating and from a mother cat to her kittens. Like feline immunodeficiency virus, feline leukemia virus is not contagious to people, dogs or other species (only to cats and other feline species).
The virus only lives for a few hours in the environment, so close contact between cats is needed for a cat to become infected. Any cat can develop the infection, but cats who are already sick (have a compromised immune system) are more likely to become infected with FeLV. So are cats who are considered high risk — cats who spend time outdoors and may interact with other cats, those who live with FeLV-infected cats, and kittens due to their underdeveloped immune system.
What Are the First Signs of Feline Leukemia?
Cats infected with FeLV typically don’t show any symptoms when first infected. As the virus replicates and starts to spread, it weakens the immune system, making affected cats more susceptible to infections and other illnesses.
Feline leukemia virus can affect a cat’s body in numerous ways. FeLV infection is one of the most common causes of cancer (e.g., lymphoma and lymphosarcoma) in cats and can also cause blood disorders like anemia. The virus also reduces the ability of a cat’s immune system to fight off infections (e.g., skin, eye, upper respiratory tract and urinary tract infections) that wouldn’t cause a problem for healthy cats.
Symptoms of Feline Leukemia
Although there aren’t specific clinical signs associated with FeLV, there are a variety of symptoms to look for:
- Decreased appetite
- Weight loss
- Behavioral changes
- Poorly groomed coat
- Pale gums
- Chronic diarrhea
- Enlarged lymph nodes
- Persistent fever
- Gum and mouth inflammation
- Seizures
Feline Leukemia Diagnosis and Treatment
Many veterinary clinics can test potentially infected cats in-clinic using a quick and simple blood test. When a cat tests positive, the veterinarian may send a blood sample to an outside diagnostic laboratory to confirm the results. They may also repeat the test at a later date to confirm an active FeLV infection, since some cats can eliminate the virus. Depending on the cat’s health status, additional testing such as complete blood count, blood chemistries and radiographs may be needed to help guide treatment and prognosis.
Unfortunately, there is no cure for feline leukemia. Treatment usually involves managing secondary infections and conditions that develop due to infection with FeLV. Cat parents with FeLV-infected cats will need to monitor their cats and contact their veterinarian if they notice changes in their cat’s appetite, behavior, bathroom habits or appearance. It’s also important to reduce a FeLV-positive cat’s exposure to secondary illnesses. For example, keep affected cats indoors and away from cats who are sick.
FeLV Life Expectancy
Cats diagnosed with FeLV can live normal lives for months or even years after diagnosis by treating secondary conditions and infections as they appear. However, on average, most persistently FeLV-positive cats live for less than three years post-diagnosis, depending on individual health conditions and complications.
Feline Leukemia Prevention
Preventing your cat from being exposed to FeLV-positive cats is the best way to protect them. Keep them indoors or restrict their outdoor activities so they don’t come in contact with cats of unknown or positive FeLV status (e.g., build a catio). If you are introducing a new cat into your home, make sure they have been tested for feline leukemia virus. If the new cat is FeLV-positive, they will need to be kept separated from any FeLV-negative cats in your home, including separate water and food dishes and separate litter boxes.
A vaccine is available for feline leukemia virus. Veterinarians recommended the FeLV vaccine for all kittens (even if they are indoor-only kittens) due to their high risk of becoming infected. Ask your veterinarian whether they recommend an annual feline leukemia virus vaccination for adult cats in your home, especially if your cat spends any time outdoors. The vaccine will not cause a positive result on FeLV tests, but it is recommended to test your cat for FeLV before receiving the vaccine. No vaccine is 100 percent effective, so it’s still important to prevent vaccinated cats from being exposed to FeLV.
Feline leukemia is a serious condition, but knowledge, early detection and preventative care can make a significant difference in a cat’s quality of life. By asking your vet about vaccination options and limiting your cat’s contact with cats of unknown or positive FeLV status, you can help protect your cat from this potentially life-threatening disease.
