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Canine Lymphoma

Lymphoma is a cancer of the lymphatic system, which is part of the immune system. It is the most common type of cancer in humans and pets. Lymphoma can affect almost any part of the body. Dogs typically are presented with enlarged lymph nodes or glands. The ones that are usually the first to enlarge are the sub mandibular lymph nodes which are just below the jawline. Dogs that are brought in for “enlarged glands” are usually totally normal, eating, and active, but have generalized lymph node enlargement. Cats rarely present with enlarged lymph nodes. Their disease is usually manifested with gastro intestinal signs, kidney signs, or respiratory signs. Cats usually present thin, with chronic diarrhea, lethargic, and a lack of appetite. Palpable lymph nodes are more likely to be internal, with the lymph nodes that drain the intestines being enlarged. Diarrhea, and weight loss that is not responsive to treatment should alert the clinician and pet owner that lymphoma is a possibility.

Diagnosis is made with fine needle aspirates, or biopsies. Sometimes special stains have to be used to confirm the diagnosis. Lymphoma usually is very responsive to chemotherapeutic drugs. Lymphoma has been studied extensively in humans and effective chemotherapy protocols are readily available. Remission can usually be achieved in 93% of dogs using a combination drug protocol. Length of remission varies, but the usual first remission length is 12-13 months. Smaller dogs tend to stay in remission longer than their larger counterparts. Once dogs come out of remission, they have a reduced chance of going into a second remission, and the length of remission is usually half of the first remission.

The usual protocol is weekly chemo treatments for 4 treatments, then every other week for 20 weeks with a week off between cycles. Weekly CBC’s (complete blood counts) have to be done before chemotherapy treatments. The white count should be above 5000. If the levels are lower, the treatment is postponed. These drugs tend to suppress the bone marrow/immune system and make the patient susceptible to infection. Treatment is usually tolerated very well and the quality of life is excellent. I can attest to this. My dog Candi had lymphoma and survived 22 months with chemotherapy. My cat Charlie had nasal lymphoma, but did not respond well to chemotherapy and lived 3 months from the initial diagnosis.
Radiation therapy has shown promise in lymphoma patients especially those affecting the head and sinuses and is now available in several institutions in the state.

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