Lymphoma is cancer derived from the white blood cells known as lymphocytes. In the canine world, it’s the most common type of tumor found in dogs. Because of its association with lymphocytes, canine lymphoma is often found in organs that work as part of the immune system, such as bone marrow or lymph nodes, though other body parts can be affected. Other common canine lymphomas include cutaneous, or skin, lymphoma and gastrointestinal lymphoma.
Some Unknowns of Lymphoma
No one knows how or why a dog gets lymphoma, though there are theories. Bacteria, viruses, exposure to chemicals and environmental influences, such as strong magnetic fields, all have been hypothesized to cause lymphoma, but there’s still no proof of cause. As well, because of the different varieties of lymphoma, there’s no set prognosis; the outcome depends on where the cancer is located, its stage of development and the treatment protocol used.
Early Signs of Cutaneous Lymphoma
As the name indicates, cutaneous lymphoma is a type of skin cancer, and it’s the most common type of lymphoma affecting dogs outside of the lymph system. Cutaneous lymphoma also can affect the foot pads as well as a dog’s gums and lips. Initial symptoms include hair loss, itching and scaling and redness of the skin. If the cancer is present in the mouth, the dog may have red, plaque-like bumps or lesions on his lips and gums, which is often mistaken for gingivitis or periodontal disease in its early stages.
Progression of Cutaneous Lymphoma
Cutaneous lymphoma may progress slowly, and it’s not unusual for a dog to be treated for an allergy or infection before he’s diagnosed with cutaneous lymphoma because the symptoms are similar to a variety of bacterial and fungal infections. As the cancer develops, the dog’s skin becomes increasingly red and thickened, often becoming ulcerated and oozing fluid. Masses in the skin also may develop. To diagnose this type of lymphoma, the vet will rely on skin biopsies, blood tests and stains to determine the type of cells involved. If the vet suspects more of the body is involved -- systemic involvement -- radiographs or ultrasounds may be necessary.
Treating Cutaneous Lymphoma
The progression of the disease drives its treatment, meaning early diagnosis may offer a wider variety of treatment options. Surgery or radiation therapy is often used to target localized lesions. Chemotherapy is the treatment of choice for generalized cutaneous lymphoma. Dogs typically respond well to chemotherapy, however, it’s normal for new lesions to develop within five months of treatment. Despite the short-term gain from treatment, the long-term prognosis for this cancer is poor; many dogs experience great discomfort with the increasing ulceration, bleeding and itching of their lesions, prompting euthanasia.