Lymphoma is a common cancer in dogs, accounting for 10 to 20 percent of all cases of cancer in canines. Also called lymphosarcoma and non-Hodgkin's lymphoma, it occurs in the lymph nodes, spleen, liver, intestinal tract and skin and is a malignant cancer. While lymphoma can't be cured, if caught in time, many dogs can achieve remission with chemotherapy treatment.
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Predisposed
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Lymphoma most often occurs in middle-aged to older dogs, with the average age being between five and nine years. The cancer seems equally prevalent in male and female dogs. However, certain breeds may be predisposed. These include Rottweilers, Scottish terriers, golden retrievers, Basset hounds and German shepherds.
Cause
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Why some dogs develop the cancer is not known. There is some speculation, according to Doctors Foster and Smith at Pet Education, that there may be a connection between exposure to pesticides or magnetic fields as well as predisposition to lymphoma being inherited. However, neither of these theories has been proven.
Symptoms
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The first symptom most pet guardians notice is a lump or swelling under their dog's skin or swollen glands. These are tumors that have developed in the lymph nodes. If the tumors have formed within the dog's intestinal tract, there may be vomiting, diarrhea, weight loss and anorexia. If the tumors have formed in the dog's lungs, there may be shortness of breath.
Diagnosis
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If your veterinarian suspects lymphoma, the doctor will most likely follow a routine physical examination with several diagnostic tests and tools. These may include blood tests, a fine needle aspirate of the tumor, biopsies, X-rays and ultrasounds.
Lymphoma is classified in stages. Stage 1 means a single lymph node or the lymphoid tissue of a single organ is cancerous. Stage 2 means several lymph nodes in the same area are diseased. At Stage 3, all lymph nodes are diseased. And, at Stage 4 the cancer has spread to the liver, spleen and/or chest. By Stage 5, the cancer is in the bone marrow.
Treatment
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The primary way in which lymphoma is treated is with chemotherapy. The chemotherapy may be delivered by injection, pill or a combination of the two. Rarely is surgery performed, and radiation is not effective against this particular type of cancer. Prednisone is often prescribed in addition to the chemotherapy. The steroid helps to reduce inflammation and may ease any discomfort the dog is experiencing.
Washington State University announced in 2008 that it would offer bone marrow transplants for dogs with cancer. The cost of this treatment is about $20,000.
Prognosis
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Untreated, dogs with lymphoma will generally not survive longer than four to six weeks. With chemotherapy, the dog's life may be extended up to a year or longer, during which time the dog is often in complete remission from the cancer. About 40 percent of dogs will achieve remission during a second bout with the cancer if chemotherapy is used.
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