Causes of Canine Lymphoma
Lymphoma is a cancer (neoplasia) that affects lymph nodes and other organs containing lymphoid tissue. In domestic dogs, the term typically is used to refer to malignant multicentric lymphoma, also called lymphosarcoma, which is a progressive, multisystemic disease caused by overgrowth of certain cells in the bone marrow, thymus, lymph nodes, liver, spleen and/or other tissues. Multicentric lymphoma is the most common lymphoma in domestic dogs. However, localized forms of lymphoma can also occur in dogs, including lymphoma of the central nervous system (CNS lymphoma), chest (mediastinal lymphoma), skin (cutaneous lymphoma), mouth and gums (oral cavity lymphoma) and gastrointestinal tract (alimentary lymphoma; affects the stomach, small intestine, large intestine (colon) and/or rectum). Lymphoma can also localize to the eyes, kidneys, liver and bone.
The causes of canine lymphoma are not known. However, there appears to be a genetic component to this disease, because certain breeds are disproportionately affected. Most lymphomas probably occur secondary to some random genetic mutation or other abnormal chromosomal recombination event. Many authorities suggest that these genetic changes can be caused or exacerbated by chronic retroviral infection, immune system compromise or electromagnetic radiation. They also may be caused by exposure to environmental carcinogens such as household cleaners, agricultural chemicals, herbicides or second-hand smoke, although these theories have not yet been proven.
There is no known way to prevent canine lymphoma.
Canine lymphoma is common and can be a potentially fatal disease in domestic dogs. Fortunately, aggressive chemotherapy in combination with other protocols has proven successful in many cases in achieving remission, especially in cases of multicentric lymphoma, which is by far the most prevalent form of lymphoma in dogs. Unfortunately, lymphoma does tend to be progressive. For some reason, female dogs seem to respond better to treatment than do males, and small dogs seem to respond better than large dogs. Treatment is not recommended for female dogs during periods of pregnancy.