Lymphoma in Dogs

Lymphoma is the cancer of lymphocytes (white blood cells). In this condition, proliferation of malignant lymphocytes within solid organs such as lymph nodes, bone marrow, liver and spleen, takes place. It is an unregulated overgrowth of cells in organs containing lymphatic tissue, such as the bone marrow, lymph nodes, thymus, liver and/or spleen.

Lymphocytes are a type of white blood cells and an integeral part of body immune system. Mostly found in lymphatic system, lymphocytes are distinguished into three different types, known as B cells, T cells and Natural Killers (NK). In lymphoma, proliferation of any of these cells can occur however, most cases involving B cells are seen.

When a lymphocyte becomes cancerous, it divides out of control and produces large numbers of cells just like it, which crowd the lymph nodes and make them swell. That is why the lymph nodes (and sometimes other lymphoid organs) appear enlarged in cases of lymphoma.

This condition is usually seen in middle to old dogs between 6-9 years of age. Certain breeds are at a higher risk of acquiring this disorder. These include Boxers, golden retrievers, saint bernard, basset hounds, Airedale terriers, Scottish terriers, and bulldogs.

 Lymphosarcoma is classified according to the location in the body in which the cancer begins. These include:

Multicentric form occurs in the lymph nodes.

Gastrointestinal form occurs in the stomach, intestines, liver and lymph nodes in the abdomen.

Mediastinal form occurs in the mediastinum, in front of the heart in an organ called the thymus. 

Hence this form of lymphosarcoma sometimes is called thymic lymphoma.

Cutaneous form occurs in the skin.

Acute lymphoblastic leukemia occurs when the disease starts in the bone marrow.

Miscellaneous forms of lymphosarcoma are less common and include those that begin in the 

nervous system, nasal cavity or kidneys.

General signs and symptoms include depression, fever, weight loss, loss of appetite, loss of hair or fur and vomiting. Other symptoms depend on location and stage of the tumor. 

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