Lymphosarcoma (Lymphoma) in Dogs
Veterinary care should include diagnostic tests and subsequent treatment recommendations.
In-depth Information on Diagnosis
Diagnostic tests are needed to recognize lymphosarcoma and exclude other diseases.
Tests may include: A fine needle aspirate using a regular syringe and needle can be performed to obtain cells from enlarged lymph nodes for microscopic analysis (cytology). Fluid that has accumulated in the chest also can be withdrawn for analysis. With the aid of ultrasound examination, needle aspirates also can be obtained from internal abdominal organs (liver, kidney, spleen) or from a mediastinal mass in the chest. A biopsy specimen can be collected if the diagnosis cannot be made on the basis of cytologic evaluation of a fine needle aspirate. A biopsy specimen can be obtained by one of several different methods. A lymph node biopsy can be collected by a taking a core of tissue with a needle biopsy instrument (so-called “Tru-Cut needle”), by making an incision to take a small piece of a lymph node or by removing the entire lymph node surgically. Needle biopsies can be obtained using sedation and local anesthesia but the lymph node removal requires general anesthesia. Biopsy specimens can be collected by endoscopy when gastrointestinal lymphosarcoma is suspected. Endoscopy involves the use of a long flexible scope and light source to examine the inner surface of the stomach and intestine. Several areas in the stomach and intestine are biopsied and submitted for examination by a veterinary pathologist. Biopsies also can be taken during an exploratory abdominal surgery, but endoscopy is much less invasive and takes less time. The biopsies taken during endoscopy are very small and may not be conclusive. If these samples are not conclusive, exploratory abdominal surgery can be performed to take larger biopsies from the gastrointestinal tract and to evaluate other abdominal organs such as the liver, spleen, and kidneys. A complete blood Count (hemogram or CBC) is performed to evaluate your pet for anemia, low platelet count, or abnormal circulating lymphocytes. Serum biochemistry tests can be performed to evaluate the general health of your dog and determine the effect of lymphosarcoma on other organ systems. High blood calcium concentration (hypercalcemia) occurs in some animals with lymphosarcoma and can cause increased water consumption, increased urinations, and kidney dysfunction. Urinalysis can be performed to evaluate kidney function or identify presence of urinary tract infection. Chest X-rays allow evaluation for a mediastinal mass, enlarged lymph nodes in the chest, or involvement of the lungs in the disease process. The mediastinum (a collection of lymphoid tissue located in front of the heart) can be the primary disease site in some dogs with lymphosarcoma. In addition, lymphosarcoma can be associated with fluid accumulation in the chest cavity. This fluid can be removed with a needle and syringe to allow the dog to breathe better and to obtain fluid for microscopic analysis. Abdominal X–rays can be used to identify enlargement of the liver, spleen, or kidneys that can occur in some animals with lymphosarcoma. Abdominal ultrasound examination can be used to identify enlargement of abdominal organs and lymph nodes in the abdomen. This procedure can also be used to guide the needle during biopsy procedures. A bone marrow aspirate is performed to determine if the disease process has affected the bone marrow. The bone marrow is responsible for making red and white blood cells and platelets. Bone marrow aspirates usually are performed using sedation and local anesthesia. The most common sites used to obtain bone marrow are the humerus (just below the shoulder) and the hip (ileum). Response to treatment may be adversely affected if lymphosarcoma is found in the bone marrow.
In-depth Information on Treatment
Treatment for lymphosarcoma may include one or more of the following: Chemotherapy is the most commonly recommended treatment for dogs with lymphosarcoma. A dog is said to be in remission when clinical evidence of the cancer disappears after treatment. Achievement of remission by chemotherapy does not mean that the animal is cured, and cancer is likely to return if treatment is discontinued.
Several different drugs alone or in combination have been used during the past 30 years to treat lymphosarcoma in dogs.
The commonly used drugs include: Prednisone (a cortisone-like drug) Vincristine (Oncovin) Cyclophosphamide (Cytoxan) Doxorubicin (Adriamycin) L-asparaginase (Elspar) Cytosine arabinoside (Cytosar)
Depending upon the drug, treatment can be given by injection under the skin (subcutaneously), intravenously or by mouth (orally). Combinations of these drugs work better than a single drug.