DogsVitalSigns

Accounting for better than five percent of all tumors known to occur in the dog, lymphosarcoma is the commonest malignancy seen in aging dogs, especially those in the eight to twelve-year range. Its cause is unknown and is relentlessly fatal, but early diagnosis combined with one or more of the therapy modes just described can comfortably prolong life for eight months to a year.

This tumor can develop in any organ or part of the body, and symptoms will naturally depend on the location. If it's in the digestive system, there may be vomiting, prolonged diarrhea, and continuing weight loss despite a good or even ravenous appetite. The liver or spleen may become quite enlarged causing a "big belly." Tumors in the chest can cause coughing and difficult breathing, as can tumefied tonsils.

In the skin form, there may be many hard, reddened areas which ulcerate easily. Some dogs show tumor development in one or both eyes, usually in the iris or just under the cornea. Any or all of these can occur in one dog, but the commonest symptom is enlargement of the lymph nodes located just under the skin on the back of the thighs, the front of the shoulders, and on either side of the throat near the jawbone. Such a dog may appear perfectly normal in all other ways and could misleadingly induce you to ignore the swellings until the tumor spreads further and causes obvious signs of illness.

Biopsy of an enlarged lymph node or suspicious skin will confirm the diagnosis. X-ray studies can confirm additional disease in the chest or abdomen and are essential when there are no external tumors. Blood studies are also helpful, about half of the dogs with lymphosarcoma tumors also have leukemia. Most cases of lymphosarcoma involve multiple parts of the body, thereby making surgical excision of the tumors impractical, if not impossible.

Chemotherapy is the method most often used and initially prednisone, a cortisone-like drug, is the medication generally prescribed. It makes your dog "feel better" and is less dangerous than most other effective drugs. These more toxic drugs may be used later on, or they are sometimes combined with the prednisone right from the beginning of therapy. Radiation treatments and immunotherapy are occasionally used as adjuncts to chemotherapy...