Feline Leukemia: What It Is, How to Spot Symptoms & What You Should Do

Feline Leukemia-How to Spot Symptoms & What You Should Do

Feline leukemia is currently present in an estimated 2-3% of cats in the United States. That may seem like a rather small percentage, but when you take into account the number of cats in our country that percentage translates into as many as 28.8 million cats currently infected.

Because the virus is relatively easy to contract, we felt the need to pen this post to help spread awareness about this life-threatening ailment. You should know how to spot the symptoms of feline leukemia and how to help prevent your cat from contracting it.

What is Feline Leukemia?

Feline leukemia is a retrovirus, meaning it creates an enzyme called reverse transcriptase. This enzyme allows the virus to place a copy of its genetics into the DNA of infected cells in order to reproduce. It’s similar to feline immunodeficiency virus or even human immunodeficiency virus (HIV), but is also quite unique in many ways, although some symptoms may seem nearly identical. Retroviruses are species specific, so feline leukemia can only be passed from cat to cat. There is no risk of human infection from an ill cat.

How is Feline Leukemia Contracted?

One of the main unique qualities of feline leukemia is its ease of contraction. It’s also important to know that very young kittens, senior cats, and felines with a compromised immune system are far more likely to contract the virus than a healthy adult cat. Males contract the virus more commonly than females, as do outdoor cats, due to their increased exposure to other neighborhood cats.

There are several ways the virus can be passed from animal to animal:

Saliva and nasal secretions

Many cats participate in mutual grooming that involves the transfer of saliva to sensitive parts of the body, including the eyes, nose, and mouth. This transfer can be completed with limited interaction, but is most common in those living with or near other infected cats. Shared food and water bowls are also a common method of infection.


An infected mother cat can easily transfer the virus to her young nursing kittens through her milk. Their undeveloped immune systems make them far more susceptible to infection. It is also possible for the mother to transfer the disease to her kittens before they are born. Kittens will become less likely to contract the virus as they progress toward adulthood.

Urine and feces

This is a far less common method of transmission but still something to consider. A shared litter box can leave infected urine and feces in a place where it could come into contact with eyes, nose, mouth, anus, etc. The virus can only survive for a few minutes outside of its host, so these transfers are less likely.

Fighting (bites)

If your cat spends much of its time outdoors, it will likely come into contact with aggressive cats in your neighborhood. In the event of a fight, saliva will likely be transferred from the biting cat’s mouth to your cat’s bloodstream. Keeping your cat on your property—or better yet, indoors—may be difficult but will prevent aggression and possible infection.

What Feline Leukemia Does to Your Cat’s Body

Feline leukemia is the most common cause of cancer in cats, and frequently leads to blood disorders. It can also cause a state of immunodeficiency that makes your cat susceptible to infection from other diseases. This means that the bacteria, virus, and fungi that a cat has lived with every day of its life will now pose a threat of major infection.

It can also cause oral disease, respiratory problems, reproductive problems, gastrointestinal disease, platelet disorders, and neurological disease, among others.

How to Spot Feline Leukemia Symptoms

Knowing what to look for can help you identify feline leukemia early, giving you the opportunity to get your cat to the vet as soon as possible.

Loss of appetite – The lack of interest in mealtime or flat out refusal to eat is a common symptom of many diseases as well as a simple upset stomach, but if prolonged it should not be ignored.

Weakness – Feline leukemia causes chronic weakness in infected cats. Again, lethargy is a common symptom of other ailments but prolonged weakness could be a symptom of something serious.

Fever – Especially in the acute stage of the disease, fever is commonly present. This can be determined by taking its temperature with a rectal thermometer (available for purchase at most pet stores).

Weight loss – The symptoms listed above pair with the deteriorating effects of the disease to cause weight loss in infected cats.

Lymphadenopathy (enlarged lymph nodes) – Enlarged lymph nodes may be hard for you to find but your vet will be able to discern if they are indeed swollen.

Pale gums – Lack of blood flow to the mouth and teeth can cause pale gum coloration.

Gingivitis – Watch for irritated and/or red gums.

Yellow eyes – Look for the whites of their eyes to have a yellowish discoloration.

How to Help Prevent Feline Leukemia

There are many ways to help keep your cat safe from this serious disease. We recommend taking as many of these steps as possible.


There are several vaccines for feline leukemia, however none of them are 100% effective so it’s important to take other precautions.


Have your cat tested regularly. Ask your vet for their advice on how often your cat should be tested based on your area and your cat’s age and lifestyle.

Limit exposure

Keeping your cat indoors or on your property and away from other cats will drastically lower their chances of contracting the virus.

Test new introductions

If you plan to add a new cat to the family, be sure to have them tested.

Spay/Neuter your pet

Spayed and neutered felines tender to wander and stray less, resulting in less exposure to possibly infected animals.

What to Do If Your Cat is Diagnosed

Unfortunately, feline leukemia ranks as the second highest cause of death in cats (next to trauma) and typically kills around 85% of infected victims within three years. That is not to say that there is no hope or you shouldn’t take action. Your veterinarian can help extend your cat’s life considerably and make them more comfortable.

They may decide to follow a vaccine regimen that provides added protection against disease in an attempt to make up for your pet’s weakened immune system. They may also add nutritional therapies and recommend keeping your cat indoors, away from other cats, and avoiding stress.

AZT–an antiviral used in humans and animals alike—can provide some relief and, in some cases, remission of the disease. It can have toxic side effects, so you may have to work with your vet to weigh the benefits versus the risks.

While feline leukemia presents a serious risk to any cat, there are ways to help keep them safe. If you suspect your cat has contracted the virus you should take them to your vet for testing immediately. Know the signs and ways to protect them and help your cat to live a long and healthy life.