The Cat Contagion

By July 2, 2014 December 14th, 2018 Uncategorized

What is feline leukemia virus?

Feline leukemia virus (FeLV) is a very common infection among cats which impairs the cat’s immune system and causes certain types of cancer. The virus has three different ‘types’ which all display varying effects on the animal. A cat with FeLV can be infected with one, two, or all three types! This infection is most likely to affect outdoor cats during the summertime, because this is when they have the most exposure to unfamiliar and unvaccinated animals.

FeLV can be transmitted in three basic ways:

1) Through contamination of eye, mouth and nose membranes when licked or bitten by an infected cat

2) Through passing of infected blood

3) Through pregnancy

What problems does feline leukemia virus cause?

FeLV is a very serious illness which, unfortunately, often results in the death of the animal. As high as 85% of the cats who are diagnosed with the disease will die within the following three years. The immune system is severely impacted in most cases, which results in an array of unique problems for the cat. All cats with FeLV are experiencing FeLV-A, which impacts the immune system. About 50% of cats will also be infected with FeLV-B, which causes tumors and abnormal tissue growths. A mere 1% of cats infected will also have FeLV-C, which causes anemia.

How common is feline leukemia virus?

FeLV is a very common infection, causing more cat deaths directly or indirectly than any other organism. It is more common among male cats as well as cats between the ages 0-6 years.

What are the symptoms of feline leukemia virus in my pets?

As the main problem associated with FeLV is immunosuppression, the symptoms will vary for each animal, depending on how the immune system is reacting. A diagnosis cannot be made based on symptoms alone, and the veterinarian may have to do a series of tests before they arrive at an accurate diagnosis. These tests may include a blood test (most common), urinalysis, or a bone marrow biopsy. That said, some of the most common symptoms include:

  • Anemia
  • Lethargy
  • Weight loss
  • Abscesses
  • Enlarged lymph nodes
  • Persistent diarrhea
  • Infections of the external ear and skin
  • Fever (seen in about 50 percent of cases)
  • Wobbly, uncoordinated movement
  • Inflammation of the nose or the eye
  • Inflammation of the gums or mouth tissues
  • Lymphoma (the most common FeLV-associated cancer)
  • Fibrosarcomas (cancer that develops from fibrous tissue)

How can I treat and prevent feline leukemia virus in my pets?

There are many preventative measures that can be taken to prevent this disease. First of all, new cats brought into the home can be tested for the virus and vaccinated if they are negative. Kittens are the most susceptible to the disease, and if they are given the proper vaccines when they are young, this makes a huge difference to lower their risk later on in life. Finally, keeping your cat indoors prevents exposure to the virus if you choose not to vaccinate.

Treatment methods in these cases will vary from animal to animal. Some animals will simply need a prescription medication to treat infections or symptoms that arise from their impaired immune system. Other animals may need special diets to help combat weight loss, or blood transfusions if affected by anemia. It all depends on the pet, and a proper treatment plan will be planned especially for them. Talk to your veterinarian today about how to keep your cat healthy and disease-free!


VIN Community Contributors. (2003, July 12). Feline leukemia virus. Retrieved from Veterinary Partner website:

(n.d.). Leukemia virus infection in cats. Retrieved from Pet MD website:

Content Contributor: Dr. Sandy Drury

LifeLearn Administrator

Author LifeLearn Administrator

H. Fraser is a LifeLearn author.

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