Lymphoma, also known is lymphosarcoma, is a cancer of the lymphocytes common in dogs. It occurs in the lymph nodes, spleen, liver and other organs. Lymphoma is a systemic disease, meaning that it spreads throughout your pet's body. While not curable, your dog's life expectancy can be expanded in many instances with chemotherapy treatment.
Lymphoma primarily affects middle-aged to older dogs. Breeds are diagnosed with the cancer in equal number, and both males and females develop the illness equally. The reason some dogs develop the cancer is not known. There is speculation that exposure to environmental toxins, such as pesticides or strong magnetic fields, may increase a dog's chances of developing the cancer, but this hasn't been proven. There are some indications that there may be a genetic predisposition to developing the cancer.
Very few dogs are actually sick when they are brought to the veterinarian and diagnosed with lymphoma. Most dogs are brought to the doctor because their guardian has found a lump or swelling. This is most often the first symptom guardians notice. Other symptoms depend upon where the tumours associated with the cancer develop. If the tumours develop in the gastrointestinal tract, the dog may vomit, lose weight and have diarrhoea. If tumours form in the chest, the dog may have shortness of breath. In the skin form, bumps, lumps and lesions are often present.
If the veterinarian suspects your dog may have lymphoma, the doctor will use several diagnostic tools to reach a definite conclusion. The tests will likely begin with a complete blood workup. This may be followed by fine needle aspirates and biopsies of the tumours. X-rays and ultrasounds may be used to examine organs that are affected by the cancer. The veterinarian will also determine to what stage your dog's cancer has progressed. In stage 1 lymphoma, the cancer is in only one lymph node and stage 2 involves several lymph nodes. Stage 3 involves all lymph nodes, stage 4 involves all lymph nodes along with some or several organs, and stage 5 includes cancer in the bone marrow.
Surgery and radiation are not often used in the treatment of lymphoma because it is a systemic disease. Chemotherapy is most often used, in various forms. These include injectable chemotherapy, and chemotherapy in oral doses. These are most often given on a weekly basis during treatment. Cyclophosphamide, vincristine, doxorubicin and prednisone are often given in combination with the chemotherapy. If your dog is diagnosed with lymphoma, you may wish to consult with a veterinary oncologist. Your veterinarian can refer you to a doctor in this speciality.
If left untreated, lymphoma can quickly be fatal. With chemotherapy, many dogs with lymphoma are living months, and sometimes years, longer than they would have without treatment. If you choose not to treat your dog with chemotherapy, the veterinarian may prescribe prednisone. The steroid will not extend your pet's life, but will ease some of the swelling and discomfort associated with the cancer. The life expectancy in this case will be only four to six weeks. With chemotherapy, life expectancy may be a year or longer.