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Lymphoma in Cats

Lymphoma is a cancer that our Tigard vets often see in cats. Lymphoma affects specific white blood cells in the cat's body called lymphocytes. Today, we discuss the types of lymphoma seen in cats, how they are diagnosed and how they are treated. 

What is lymphoma in cats?

Lymphoma is a systemic cancer that affects the lymphocytes of the cat's immune system. Lymphocytes travel through your cat's body in the blood and lymphatic vessels. This condition is associated with the viral infection feline leukemia.

Increasing numbers of cats being immunized against feline leukemia as part of the annual wellness and vaccination care are causing both feline leukemia and lymphoma to become less common than they once were, although there is still much room for improvement. Cats are diagnosed with lymphoma in approximately 30% of all cancer cases.

What causes lymphoma in cats?

Lymphoma in cats is primarily caused by the uncontrolled growth of abnormal lymphocytes, which are a type of white blood cell. While the exact cause of this abnormal growth is still unknown, but factors such as genetic predisposition, exposure to certain viruses, and environmental factors have been suggested to play a role in the development of lymphoma in cats. 

Where is lymphoma typically found in cats?

Lymphocytes are found throughout your cat's body, which means that lymphoma could develop in multiple organs.

The disease commonly affects the cat's nasal cavity, gastrointestinal tract, or mediastinal. Veterinarians will classify your cat's lymphoma based on the location of the disease and the size of the lymphocytes (either small cell or large cell).

  • Intestinal lymphoma is the most common form of lymphoma in cats. This cancer is found in the GI tract and is most often seen in cats over 9 years of age.
  • Mediastinal lymphoma affects the lymphoid organs found within the cat's chest. These organs include the lymph nodes and the thymus. Strongly associated with feline leukemia, this form of lymphoma is typically seen in cats around 5 years of age.
  • Renal lymphoma is also associated with feline leukemia. Renal lymphoma affects the cat's kidneys and may result in kidney failure.

What are the most common symptoms of lymphoma in cats?

Your cat's lymphoma symptoms will depend upon where the cancer is located.

  • A cat with intestinal lymphoma will often experience diarrhea, weight loss and vomiting. In cats with large cell intestinal lymphoma these symptoms can come on very rapidly, in a matter of just days or weeks, whereas cats with the small cell version of the disease will show a much slower onset of symptoms.
  • Because mediastinal lymphoma is found in the cat's chest area breathing difficulties are a common symptom of the disease. In some cases fluid can build up around the tumor making it increasingly difficult for the cat to breathe
  • As toxins build up in the blood system, cats with renal lymphoma will show common symptoms related to kidney failure including vomiting, reduced appetite, and increased thirst. In some cases the cat's central nervous system may be affected, in which case symptoms such as seizures, instability while walking and behavior changes may occur.

How is lymphoma in cats diagnosed?

Depending on the extent of the disease and the location, either fine needle aspiration cytology or a biopsy will typically be used to diagnose lymphoma in cats.

In some cases, vets may require sampling of bone marrow or other organs, or molecular testing on tissues or blood in order to provide a definitive diagnosis of lymphoma.

Diagnostics may also include:

  • Bloodwork such as CBC (Complete Blood Count) and full chemistry panel
  • Testing for feline leukemia FeLV/FIV
  • Urinalysis
  • Ultrasound imaging to evaluate the cat's GI tract, spleen, liver and lymph nodes
  • X-rays to evaluate lungs and lymph nodes

Can lymphoma be misdiagnosed?

Yes, lymphoma in cats can sometimes be misdiagnosed due to its similarity with other diseases or conditions. This can happen if the initial diagnostic tests are inconclusive or if the symptoms are mistaken for those of another ailment. 

Lymphoma in cats can sometimes be misdiagnosed as inflammatory bowel disease (IBD) due to similar symptoms such as vomiting, diarrhea, and weight loss. Additionally, it can also be mistaken for kidney disease or pancreatitis, as these conditions may present with similar clinical signs in cats. 

However, with thorough examination and further testing, veterinarians can usually differentiate Lymphoma from other conditions to provide an accurate diagnosis. 

What is the treatment for lymphoma in cats?

Veterinarians primarily use chemotherapy to treat cats diagnosed with lymphoma, although they may also consider radiation as an alternative option. Additionally, they may recommend surgery, with or without chemotherapy, if the lymphoma is localized to a specific area such as the cat's nasal region or abdomen.

Your veterinarian or veterinary oncologist will be able to recommend the best treatment for your pet based on their specific condition.

If for any reason chemotherapy is not an option prednisone may be prescribed as palliative or hospice care.

What are the stages of feline lymphoma?

Feline lymphoma typically progresses through four stages, known as Stage I, Stage II, Stage III, and Stage IV. In Stage I, the cancer is localized to one lymph node or a specific area. As it advances to Stage II, the disease spreads to multiple lymph nodes in a particular region. In Stage III, the cancer spreads beyond the lymph nodes to other organs or tissues. Finally, in Stage IV, the cancer has metastasized and spread throughout the body.

What is the prognosis for cats diagnosed with lymphoma?

With treatment, the prognosis for cats diagnosed with gastrointestinal large cell lymphoma is about 6 - 9 months. A small percentage of cats that reach full remission with treatment can live up to 2 years, although this is rare.

Cats diagnosed with small cell gastrointestinal lymphoma will require ongoing care with oral medications but could live 2 - 3 years with the disease of longer.

Sadly, cats diagnosed with mediastinal lymphoma and feline leukemia face a poor prognosis of about 3 months.

Cats that do not have feline leukemia, who are diagnosed with mediastinal lymphoma, may show a full or partial response to chemotherapy. These cats have an average survival time of about 9-12 months.

Unfortunately, renal lymphoma has a very poor prognosis. Cats with this type of lymphoma typically survive only 3-6 months on average, although there are isolated reports of cats surviving far longer. Renal lymphoma tends to spread to the brain and central nervous system, affecting approximately 40% of renal lymphoma cases and worsening the prognosis for this disease.

If not treated with chemotherapy, large cell lymphoma in cats will progress very quickly and soon be fatal. Palliative treatments may help to extend the cat's quality of life by a few weeks or possibly months.

    Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

    Contact our Tigard vets today if your cat is experiencing an emergency. If you suspect lymphoma, contact your primary vet first to get an official diagnosis.

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