Lymphoma is a type of cancer that is caused by the uncontrolled proliferation of an immature form of a white blood cell called a lymphoblast. Lymphoma, which may also be called lymphosarcoma (LSA), is a common type of cancer in middle-aged or older dogs and cats. Cats are more likely to develop lymphoma when they are infected with the feline leukemia virus or feline immunodeficiency virus. Many owners are shocked when their pet is diagnosed with lymphoma because animals tend to feel and act relatively normally until the late stages of the disease.
Cancerous lymphoblasts can invade any of a number of different organs and an animal's symptoms vary accordingly. Pet owners may notice enlarged lymph nodes under the jaw, in front of the shoulder blades, or behind the knees. Abnormal looking patches of skin are also possible. If the disease affects the intestinal tract, vomiting, diarrhea, and weight loss can result. The kidneys, liver, and spleen may also be involved. Lymphoma can usually be diagnosed when a sample of the infected tissues is examined under the microscope. A routine health workup that includes blood work and a urinalysis is necessary to obtain a picture of the patients overall health. In some cases, additional tests may need to be run to plan appropriate treatment.
If cancerous lymphoblasts are limited to one part of the body, surgery or radiation therapy can be helpful. In many cases, however, lymphoma cells are present in many different locations and surgery is not an option. This type of cancer responds quite well to various chemotherapy protocols. Remissions can be lengthy and side effects are generally mild, but lymphoma is eventually fatal in the great majority of cases.
Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008