Lymphoma Cancer in Cats
What are lymphomas?
Lymphoma is a diverse group of cancers that originate in lymphocytes - a type of white blood cell in the immune system.
The commonly affected sites are lymph nodes, spleen and bone marrow, but lymphoma can occur in almost any tissue in
the body where there is lymph tissue such as the gastrointestinal tract, eyes, central nervous system, bone, testes,
bladder, heart, and nasal cavity. Lymphoma is one of the most common cancers in cats, with the median age at diagnosis
11 years old.

Lymphoma can be classified into several categories:
  • Multicentric lymphoma
  • Mediastinal lymphoma
  • Alimentary/intestinal lymphoma
  • Nodal lymphoma
  • Leukemic lymphoma
  • Extranodal lymphoma

Alimentary/intestinal lymphoma
This type of lymphoma can be either specific to the intestine or involve other organs such as the liver. The most common
site is the small intestine (50-80% of cases), followed by the stomach (25% of cases) and colon. It can be present as either
a single tumor or can be diffused (spread) throughout the intestine and muscle layers that can interfere with food passage.

Mediastinal lymphoma
This type of lymphoma can involve the thymus and lymph nodes within the chest cavity, and is frequently accompanied with
fluid accumulation. Most cats with mediastinal lymphoma are young and positive for feline leukemia virus.

Nodal lymphoma
Involvement of peripheral (external) lymph nodes alone represents only about 4-10% of cases in cats, however, over 25%
of cats with other lymphoma present in other body locations will also have affected lymph nodes.

Extranodal lymphoma
The most common sites for this type of lymphoma are the kidneys, nasal cavity, eyes, central nervous system and the skin.
Kidney lymphomas represent approximately 5% of all lymphomas and extend to the central nervous system in 40-50% of
cats. Lymphoma in the nose is usually a localized disease but spread to other sites have been reported in some cases.

What are the symptoms of lymphoma in cats?
The symptoms will depend on the tumor's location and how advanced the disease is. Regardless of the lymphoma location,
blood tests may show reduced number of red blood cells. The alimentary/intestinal lymphoma is usually associated with an
abdominal mass, enlarged lymph nodes, weight loss, lack of appetite, diarrhea, and occasional vomiting. The mediastinal
lymphoma is usually associated with shortness of breath, fast breathing, sounds in the lungs and fluid accumulation in the
chest. Cats with nodal lymphoma will typically show signs of weakness and depression. Cats with lymphoma affecting the
central nervous system will show sudden onset of weakness, bladder paralysis and lack of muscle coordination. Cats with
lymphoma in their nose will frequently show nasal discharge, bleeding deformity, or shortness of breath.

How is the diagnosis made?
Pets with suspected lymphoma will have a variety of tests done to confirm the diagnosis, including physical exam, blood
tests, urinalysis,
imaging studies and biopsy. In many cases, fine-needle aspirates of the affected area is sufficient to
confirm lymphoma but
biopsy remains as the gold standard for any cancer diagnosis. After confirming the diagnosis, it is
important to evaluate how advanced the disease by
imaging techniques such as ultrasound, X-rays, CT scan or MRI in
order to plan an appropriate treatment.

Does cancer cause pain in cats and dogs?
Pain is common in pets with cancer, with some tumors causing more pain than others. In addition to pain caused by the
actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy or
chemotherapy. Untreated pain decreases the pet's quality of life, and prolongs recovery from the illness, treatment or
injury. It is, therefore, essential that veterinary teams that are taking care of pets with cancer should also play a vital role in
educating pet owners about recognizing and managing pain in their pets. The best way to manage cancer pain in pets is to
prevent it, a term referred to as preemptive pain management. This strategy anticipates pain ahead of time and
administers pain medication before the pet actually experiences pain, thus ensuring the pet's maximum comfort.  To learn
more about which tumors are likely to cause a lot of pain, how to recognize pain in pets with cancer and what cancer pain
management options are available for your pet, please visit the
Cancer Pain Management section.

How important is nutritional support for pets with cancer?
Cancer cachexia (a term referring to progressive severe weight loss) is frequently observed in pets with cancer. Pets with
cancer lose weight partly because of lack of appetite and partly because of cancer-induced altered metabolism. Some of
the causes for decreased appetite are related to the cancer itself (for example, tumors may physically interfere with food
chewing, swallowing, and digestion process) and some may be related to the side effects of cancer treatment (for example,
some chemotherapy drugs cause nausea and vomiting, and radiation therapy can cause mouth inflammation).

Proper nutrition while undergoing cancer treatment is essential to maintain your pet's strength, improve survival times,
quality of life and maximize response to therapy. Adequate nutritional support was shown to decrease the duration of
hospitalization, reduce post-surgery complications and enhance the healing process. Additionally, pets with cancer need to
be fed diets specifically designed to provide maximum benefit and nutritional support for the patient. To learn more, please
visit the
Cancer Nutrition section.

What are the treatment options for cats with lymphoma?
Chemotherapy remains as the treatment of choice, and combining several different chemotherapeutic drugs has shown
greater benefit compared to single drugs. The most effective chemotherapeutic drugs currently in use include the
combination of doxorubicin, L-asparaginase, polyethylene glycol-L-asparaginase, vincristine, cyclophosphamide, and/or
prednisone. If multi-drug therapy cannot be used, single drug doxorubicin or prednisone can be offered as an alternative.

Are there any clinical trials for cats with lymphoma?
Although there are no clinical trials evaluating new treatments specifically in lymphoma, there are several clinical trials
available for cats with any tumor type for which your cat may qualify. To learn more these trials (which are partially or fully
funded by the institutions), please visit the
Cat Clinical Trials (any tumor type) section. Additionally, there is one clinical trial
evaluating how often cats with lymphoma are deficient in cobalamin (vitamin B12). To learn more about this study, please
visit the
Cat Lymphoma Clinical Trials section.

What is the prognosis for cats with lymphoma?
The prognosis for cats with lymphoma is not as good as for dogs, and will depend on a variety of factors such as
lymphoma type, location, and how advanced it is. Complete response rates range from 50-70% after multi-drug
chemotherapy and overall survival is approximately 6 months. For those cats who responded to chemotherapy, 25-30% of
them enjoy long-term survival (more than 1 year). Unfortunately, it cannot be determined beforehand which cats will
respond.

Alimentary/intestinal lymphoma
The median survival of cats with this type of lymphoma is 7-10 months following doxorubicin-based chemotherapy
treatment. One study of 28 cats who did not receive doxorubicin-based treatment showed that the median survival of these
cats was 50 days.

Mediastinal lymphoma
Cats with mediastinal lymphoma positive for feline leukemia virus (FeLV)  face a poor prognosis, with median survival times
of 2-3 months after chemotherapy. Cats who are negative for FeLV have much better prognosis, with 90% experiencing
high response to chemotherapy.

Nasal lymphoma
Cats with lymphoma in their nose face the best prognosis. Radiation therapy or chemotherapy are able to control the tumor
and the cats enjoy a median survival time of 1.5 years. However, cats with both lymphoma and FeLV infection face shorter
survival.

Additional online resources about lymphoma in pets:
Gastric lymphoma in cats (by Veterinary Society of Surgical Oncology)
Large intestine lymphoma in cats (by Veterinary Society of Surgical Oncology)
Small intestine lymphoma in cats (by Veterinary Society of Surgical Oncology)
Gastric lymphoma in cats (by Veterinary Society of Surgical Oncology)
Nasal cavity lymphoma in cats (by Veterinary Society of Surgical Oncology)
Spinal cord lymphoma in cats (by Veterinary Society of Surgical Oncology)
Kidney lymphoma in cats (by Veterinary Society of Surgical Oncology)

Lymphoma in Cat by Doctors Foster and Smith
Feline lymphoma (by Washington State University)
Lymphoma in cats and dogs (by Michigan Veterinary Specialists)

Sources:
  • Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
  • Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins, 1998.
© 2007 Pet Cancer Center. ALL RIGHTS RESERVED.
Last updated 10/5/2014
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