Lymphocytic Leukemia in Cats

Lymphocytic leukemia affects cats of every age.
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It's scary enough to get a diagnosis you can barely pronounce or spell, but when it includes the word "leukemia" it suddenly gets scarier. While the survival rates for cats with some forms of lymphocytic leukemia are high, with some living nearly normal lives, other cats are not so fortunate.

What Is It?

Lymphocytic leukemia, in short and simple terms, is a cancer that starts in the bone marrow and quickly spreads to other areas of the body. Lymphocytic cells, or certain types of white blood cells, become misshapen and cancerous and speed the progress of the disease. The liver and spleen are usually the first organs affected. There are two types of this leukemia, acute and chronic.


Acute lymphocytic leukemia is fast-moving and severe. Sadly, cats affected by this acute form of cancer usually survive only a few months after they are diagnosed, even with treatment. The cancer cells multiply and spread rapidly throughout the whole body in acute cases. This is why the expected survival time is so short. Treatment can slow the progress of the cancer somewhat, but usually does not stop it. A cat with the acute form of this cancer will usually survive less than a year, and sometimes only a few weeks from the time of diagnosis.


Chronic lymphocytic leukemia spreads gradually instead of rapidly like acute cases. Affected cells reproduce slowly and take time to spread throughout the body. Depending on the speed of progression, cats with chronic lymphocytic leukemia can sometimes live as long as a healthy cat if the cancer is caught early or is especially slow-moving. Treatment can also slow down the spread of the cancer.

Feline Leukemia Virus

While not technically a form of lymphocytic leukemia, the feline leukemia virus is often linked with both acute and chronic lymphocytic leukemia. According to "The Merck Veterinary Manual," nearly 30 percent of cats with feline leukemia virus also develop lymphocytic leukemia. On the other hand, Dr. E. Gregory MacEwen, professor of veterinary oncology/internal medicine, found that 60 percent of cats with lymphocytic leukemia also test positive for the feline leukemia virus. The virus is one of the only forms of cancer that can be spread between cats. It is spread through saliva and blood. There is a vaccine available to prevent infection. Symptoms of feline leukemia virus are similar to those of lymphocytic leukemia, and blood work, ultrasounds and other testing may be necessary to determine exactly what is affecting your cat.


Rapid weight loss is one the first and most noticeable signs of lymphocytic leukemia. Most cats will stop eating or eat very little and might vomit, have diarrhea, act depressed and lethargic and have a fever. Some cats with the chronic form of lymphocytic leukemia will not have any symptoms until the disease has progressed. Regular veterinary checkups can catch this type of leukemia early.


Chemotherapy is the primary treatment for lymphocytic leukemia. A specific combination of anti-cancer drugs will be selected by your veterinarian depending on the type and severity of the leukemia. Chemotherapy may be injections administered at the clinic, or pills given at home. Fortunately, cats do not suffer many of the same side effects from chemotherapy as people. They keep their hair and don't usually have vomiting or nausea.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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