Lymphoma and lymphosarcoma are cancers that develop from lymphatic tissue which is in lymph nodes but also in other organs such as bone marrow, the liver and the spleen, intestines and skin. The first sign of illness is often a swelling to a single lymph node in the neck, armpit, groin or hind leg, in pets over seven years old, sometimes younger. Chest involvement leads to breathing difficulties. Intestinal involvement causes loss of appetite and gastrointestinal signs. Skin lymphoma mimics a variety of less severe skin diseases.
A definitive diagnosis is made by examining a fine needle aspirate collected from the mass. While only one lymph node may be enlarged, in most dogs and cats the disease is in fact more widespread. The affected lymph node should be surgically removed. Blood counts and bone marrow biopsy give clues to whether the lymphoma has spread. In our experience combination chemotherapy can produce a prolonged, sometimes a permanent remission in small individuals but is less effective in larger dogs.