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Lymphosarcoma (Lymphoma)

Liaison: Tina Oswald
Email: tinaoswald@cerebussamoyeds.com

Lymphosarcoma (LSA) is caused by a cancerous proliferation of lymphocytes (cells that normally function in the immune system) and is the third most common cancer in dogs. A lymphocyte is a type of white blood cell which develops in lymph nodes and other lymphoid tissues such as the spleen, thymus, gastrointestinal tract, and bone marrow. When abnormal lymphocyte proliferation occurs in one or more tissues it is called lymphosarcoma (if confined to the bone marrow it is called leukemia).
LSA is further broken down into B-Cell or T-Cell Lymphosarcoma. B-cells and T-cells are specific types of lymphocytes. Most dogs have B-cell LSA and of the two, it’s easier to treat. Note: Easy way to remember is “B” is for “Better” and “T” is for “Terrible”
Most dogs diagnosed with LSA are between the ages of 6-9 years.

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Signs and Symptoms

Clinical signs may be present depending on where the LSA is. For example in LSA affecting the gastrointestinal tract, the dog may present with diarrhea or vomiting.

There are 5 Stages of Lymphosarcoma

Stage I: Enlargement of ONE lymph node - usually under the jaw. This is not painful and can go undetected by the owner. It is rarely diagnosed at this stage.
Stage II: Enlargement of more than one lymph node in one region of the body
Stage III: Multiple lymph nodes enlarged throughout the body. Note: Stage IIIA is usually the earliest at which LSA is detected.
Stage IV: Spleen and/or Liver involved
Stage V: Bone marrow or other organs involved (e.g. gastrointestinal tract, skin, nervous system)

There are also subclasses A and B to the stages

A – shows no signs of illness
B - indicates clinical signs such as vomiting, diarrhea, fluid in the lungs

Causes

The cause of Lymphosarcoma is not known.

Risk Factors

Although the cause and genetics of lymphosarcoma are not known, it is thought to ‘run in families’ in some breeds.

Diagnostic Tests

A basic diagnosis of lymphoma can often be achieved through aspiration of an affected lymph node and cytology (evaluation of cells from the lymph node aspirate). Additional tests are performed to determine the overall health of the dog and the stage of the disease, and to further refine the diagnosis:

CBC (Complete Blood Chemistry) test -Increased serum calcium is associated with a poorer outcome
Thoracic radiographs (x-rays of chest area)
Abdominal ultrasound
Bone marrow aspiration and examination
Immunophenotype (to differentiate B cell vs T cell LSA)
Biopsy of spleen and/or liver Note: If emergency splenectomy is preformed, a small sample should be sent out for pathology.

Treatment Guidelines

Note: Treatment of animals should only be performed by a licensed veterinarian. Veterinarians should consult the current literature and current pharmacological formularies before initiating any treatment protocol.

LSA can be treated, but is not considered curable. The goal of treatment is to extend life via remission of the disease.

Prednisone Only – 1-2 months survival time
Radiation
Chemotherapy - (Standard treatment for most patients). There are a few different “Protocols” that are used for Lymphosarcoma. Each uses multiple drugs, with one or more drugs given weekly. Some are injectable drugs and/or given orally.

VELCAP Protocol from TUFT University - combines 5 drugs: Vincristine, Cytoxan, Prednisone, Adriamycin, and L-asparaginase
Madison (U of Wisconsin) Protocol - Combines 5 drugs (same drugs as VELCAP but with different dosing regimen): L-asparaginase, Vincristine, Cytoxan, Adriamycin & Prednisone. Another Wisconsin protocol, L-VCA short, uses only 4 of the drugs, Vincristine, Cytoxan, Adriamycin & Prednisone.
COP Protocol – Combines 3 drugs: Vincristine, Cytoxan and Prednisone

Dogs usually do not have the extreme side effects with Chemotherapy that humans do. That is not to say there aren’t any, such as nausea and occasional diarrhea. Some owners notice the dog losing its whiskers.

Management

Some research has shown that high-fat, low-carbohydrate diets may be good for cancer patients. Cancer cells use simple carbohydrates such as glucose for energy, and some have difficulty utilizing fat, so you may favor normal cells, while providing extra energy to your dog, by feeding a diet rich in a high-quality fat sources and low in carbohydrates. The type of fat may also be important – n-3 polyunsaturated fatty acids such as are found in fish oils being recommended.
In general, if you feed your cancer dog store-bought food, look for one that is low in carbohydrates and moderate in protein content. You can add the fatty acids to meals in the form of fish oil, flax seed oil and many other oils found in most health food stores.
The only commercially produced dog food that has been scientifically studied for its effect on dogs with cancer is Hill's Prescription Diet Canine n/d. This dog food was found to appreciably prolong the lives of dogs with lymphoma. It was not tested on dogs with other types of cancer.