Lymphoma is a type of cancer commonly seen in cats that affects specific white blood cells called lymphocytes. In today's blog, our Glendale vets explain the types of lymphoma seen in cats, how they are diagnosed and how they are treated.
What is lymphoma in cats?
Lymphoma is 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 of feline leukemia.
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. Lymphoma makes up approximately 30% of all cancers diagnosed in cats.
What causes lymphoma in cats?
Viruses FeLV and FIV often cause lymphoma in cats. Vaccination against FeLV and testing for both these viruses help with disease prevention and spread. Avoiding contact with FeLV or FIV-infected cats and areas with smoke can also prevent 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.
Common locations of the disease include the cat's nasal cavity, gastrointestinal tract, or mediastinal. Feline lymphoma will be classified based on the stage, location of the disease, and 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 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 at the most common symptoms of lymphoma in cats?
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 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
What is the treatment for lymphoma in cats?
Chemotherapy is the primary treatment used for cats diagnosed with lymphoma although radiation can also be an option and 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 will be able to 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 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 or 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.
Renal lymphoma, unfortunately, carries a very poor prognosis. Average survival with this type of lymphoma is only 3-6 months, though there are isolated reports of cats surviving far longer. Renal lymphoma tends to spread to the brain and central nervous system; this occurs in approximately 40% of renal lymphoma 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 to extend the cat's quality of life by a few weeks or possibly months.
Can lymphoma in cats be misdiagnosed?
Many cats get sick but never receive a definitive diagnosis of lymphoma. Because some diagnostic tests are expensive, a family veterinarian may give a presumptive diagnosis based on clinical exam findings without performing further tests.
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.