Lymphosarcoma (Lymphoma) in Dogs
By: Dr. Kimberly Cronin
Eighty to 90 percent of dogs treated for lymphosarcoma by chemotherapy achieve remission and average survival time is one year. Ten to 15 percent of dogs treated for lymphosarcoma survive 2 years or more.
It often is possible to treat pets successfully a second time using different drugs or radiation therapy when relapse occurs. Different treatment approaches are necessary because the malignant lymphocytes have become resistant to the drugs used previously. It is more difficult to treat animals experience a second or third relapse and remission times generally are shorter.
In some circumstances, radiation therapy may be recommended in addition to or instead of chemotherapy. Radiation therapy requires referral to a specialty institution that offers radiation therapy because it requires specialized equipment and training. Radiation therapy may be recommended if the pet has lymphosarcoma localized to a single site.
It is essential, in this situation, to conduct a thorough search for other areas of involvement. Chemotherapy should be used in conjunction with radiation therapy if other areas of involvement are suspected. A full course of radiation involves a total of 10 to 16 treatments given 3 to 5 times a week. Adverse effects vary depending upon the region of the body treated and the number of treatments given. Animals must anesthetized for each treatment to prevent movement during radiation exposure.
Treatment of one-half of the body has been used in dogs that have come out of remission. If a good response is obtained, the other half of the body is treated 3 to 4 weeks later. Adverse effects from this type of radiation therapy are similar to those observed after chemotherapy and include gastrointestinal symptoms and low white blood cell counts.
Radiation also can be used if lymphosarcoma is causing in a specific location of the body is discomfort or clinical signs. This type of treatment is called palliative radiation therapy, and involves use of a few large doses of radiation to the affected area. Adverse effects usually are minimal with this type of radiation therapy.
Surgery rarely is used in the treatment of lymphosarcoma, and is more commonly used to make a diagnosis of lymphosarcoma (i.e. to obtain biopsy specimens for examination by a veterinary pathologist).
