A lymphoma is a type of cancer that starts in the lymphocytes, which are a type of white blood cell that is part of the immune system. Lymph nodes, the spleen and bone marrow are the parts of the body that are most often affected by a lymphoma, but it can affect any part of the body that has lymph tissue, which is most of the body. A multicentric lymphoma is a classification of lymphomas that affects multiple lymph nodes in the body.
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Prevalence
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Lymphomas are a common cancer in dogs and multicentric lymphomas account for about 80 percent of lymphomas. In 2007, the Pet Cancer Center estimated that there were three cases of lymphomas for every 200,000 dogs under a year old and about 84 cases for every 100,000 dogs aged 10 to 11.
Symptoms
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The most common symptom is swollen lymph nodes. Dog owners often mistake these as tumors, but this usually leads to the dog being taken to a veterinarian for proper diagnosis. Other symptoms may include loss of appetite and weight, vomiting, diarrhea, shortness of breath, increased thirst and urination, and fever.
Diagnosis
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Diagnosis will begin by the vet feeling for the swollen lymph nodes. The vet will then need a sample of the cells from the swollen lymph nodes. This is usually first done by aspirating liquid from the nodes with a needle. If this does not yield enough cells for proper diagnosis, then a biopsy of the lymph nodes is done. The cells are looked at under a microscope to confirm the lymphoma and to determine what kind of lymphoma it is.
Treatment
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The usual treatment for multicentric lymphoma is chemotherapy. Vincristine, adriamycin, cyclophosphamide, L-asparaginase, and prednisone are the most common drugs used to treat lymphoma. The drugs are chosen based on the type of lymphoma the dog has. Some chemotherapy involves high doses of drugs for short periods and others involve low doses of drugs that are given for the remainder of the dog's life. Fortunately, side effects such as nausea or hair loss are rare. Another treatment option is half-body radiation. The dog has the front half of his body irradiated two days in a row and then several weeks later will have the back half of his body irradiated two days in a row. This is sometimes done so the dog won't have to take drugs for the remainder of his life.
Prognosis
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If lymphoma is left untreated, the normal life expectancy of a dog after being diagnoses is only two months. However, with chemotherapy, more than 90 percent of dogs will see some improvement and about 75 percent will go into remission. How much improvement is seen and how long the remission lasts will depend on the type of lymphoma, how quickly it is caught and treated, and what type of treatment is given.
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