Lymphoma is a common type of cancer in cats. It affects specific white blood cells called lymphocytes. In this blog post, our veterinarians explain the types of lymphoma seen in cats and how they are diagnosed and treated.
What is lymphoma in cats?
Feline lymphoma is a malignant cancer of the lymphatic system, the complex structured arrangement of internal tissues and organs that directly or indirectly influences almost every aspect of a cat's physical body.
A cat's lymphatic system is an intricate network of components that move life-sustaining substances through a cat's body and help prevent harmful agents from circulating. Parts of this system include the bone marrow, spleen, thymus gland, and "gut-associated" lymphoid tissue, which lines the surface of various areas of a cat's body and keeps it from being exposed to infectious agents.
Specifically, feline lymphoma affects the lymphocytes, a type of white blood cell that's part of the immune system. Lymphocytes travel through the blood and lymphatic vessels in the cat's body. Lymphoma is associated with feline leukemia, a viral infection.
Thanks to increasing numbers of cats being immunized against feline leukemia as part of the annual wellness and vaccination care, both feline leukemia and lymphoma are becoming less common than they once were, although there is still much room for improvement.
Where is lymphoma typically found in cats?
Lymphocytes are found throughout your cat's body, meaning lymphoma can potentially develop in multiple organs.
Common areas affected by the disease include the cat's nasal cavity, gastrointestinal tract, or mediastinal. Your cat's lymphoma will be classified based on its location and the size of the lymphocytes (either small cells or large cells).
- Intestinal lymphoma is the most common form of lymphoma in cats. This cancer is found in the gastrointestinal tract and is most often seen in cats over nine years of age.
- Mediastinal lymphoma affects the lymphoid organs found within the cat's chest, including the lymph nodes and the thymus. Strongly associated with feline leukemia, this form of lymphoma is typically seen in cats around five 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?
Lymphoma in cats will depend upon where the cancer is located.
- A cat with intestinal lymphoma often experiences diarrhea, weight loss, and vomiting. In cats with large-cell intestinal lymphoma, these symptoms can come on very rapidly, in a matter of 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 disease symptom. 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 typical symptoms related to kidney failure, including vomiting, reduced appetite, and increased thirst. In some cases, the cat's central nervous system may be affected, and seizures, instability while walking, and changes in behavior may occur.
How is lymphoma in cats diagnosed?
Depending on the extent of the disease and its location, lymphoma in cats is typically diagnosed using fine needle aspiration cytology or a biopsy.
In some cases, vets may require sampling of bone marrow or other organs or molecular testing of tissues or blood to provide a definitive lymphoma diagnosis.
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
What is the treatment for lymphoma in cats?
Chemotherapy is the primary treatment for cats diagnosed with lymphoma, although radiation can also be an option. Surgery (with or without chemo) may be recommended if the lymphoma is confined to a single area, such as the cat's nasal area or abdomen.
Your veterinarian or veterinary oncologist can recommend the best treatment for your pet based on its specific condition.
If, for any reason, chemotherapy is not an option, prednisone may be prescribed as palliative or hospice care.
What is the prognosis for cats diagnosed with lymphoma?
With treatment, the prognosis for cats diagnosed with gastrointestinal large-cell lymphoma is about six to nine months. A small percentage of cats that reach full remission with treatment can live up to two years, although this is rare.
Cats diagnosed with small cell gastrointestinal lymphoma will require ongoing care with oral medications but could live two to three years with the disease for longer.
Sadly, cats diagnosed with mediastinal lymphoma and feline leukemia face a poor prognosis of about three 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. The average survival time with this type of lymphoma is only three to six months, though there are isolated reports of cats surviving far longer. Renal lymphoma tends to spread to the brain and central nervous system, which occurs in approximately 40% of cases and worsens 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 extend the cat's quality of life by a few weeks or 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.