Symptoms and Prevention and Treatment Methods of Lymphosarcoma in Dogs and Cats

There are two types of lymphosarcoma: one occurs in lymphoid organs and tissues and is called malignant lymphoma, and tumor cells (lymphocytes) may be present in the peripheral blood; the other occurs in the bone marrow and is called lymphoid leukemia, and tumor cells (lymphocytes) are often seen in the peripheral blood. Its cause is still unclear, and feline leukemia virus may be the pathogen of lymphosarcoma in some cats. Surveys show that among cats with leukemia, 1/3 develop lymphosarcoma. Among cats with lymphosarcoma, nearly 70% test positive for feline leukemia virus.

Key points for diagnosis

Lymphosarcoma can be divided by anatomical site into multicentric lymphosarcoma in dogs and cats, alimentary tract lymphosarcoma, thymic lymphosarcoma, cutaneous lymphosarcoma, and lymphoid leukemia. In addition, cats also have central nervous system lymphosarcoma and kidney and eye lymphosarcoma.

1. Multicentric lymphosarcoma in dogs and cats is mainly manifested as depression, emaciation, symmetric enlargement of all lymph nodes throughout the body, and enlargement of the spleen and liver.

2. Alimentary tract lymphosarcoma in dogs and cats is mainly manifested as emaciation, vomiting, and diarrhea, with enlargement of the lymphoid tissue in the gastrointestinal wall and mesentery.

3. Thymic lymphosarcoma in dogs and cats is usually limited to the thymus, is mostly primary, and occurs more often in young animals.

4. Cutaneous lymphosarcoma in dogs and cats mainly presents as scattered or densely distributed firm nodules in the skin and subcutis ranging in size from a grain of rice to a fingertip. The nodule areas lose hair, and some form scabs or ulcers. Cutaneous lymphosarcoma often develops into multicentric lymphosarcoma.

5. Lymphoid leukemia is mainly manifested as lethargy, anorexia, pale conjunctiva, enlargement of the spleen and lymph nodes, and sometimes elevated body temperature or symptoms of bacterial infection. Laboratory tests: increased lymphoid tumor cells, sometimes up to 100000/ul. Decreased red blood cells, granulocytes, and platelets. The clinical symptoms of lymphosarcoma in other tissues and organs are all related to the affected tissue or organ. Confirmation of diagnosis requires biopsy examination of lymphosarcoma tissue (such as lymph nodes, bone marrow, etc.).

Prevention and treatment methods

1. When the granulocyte count is >3000/ul, bone marrow suppressive drugs can be used, such as cyclophosphamide treatment (see systemic lupus erythematosus). If the granulocyte count<3000个/ul或血小板<75000个/ul时，应用环磷酰胺能导致感染或出血。

2. Treatment of canine lymphosarcoma: (1) Vincristine sulfate 0.75mg/m2, (m2 is body surface area, m2=45 x body weight kg + 7/body weight kg + 90), administered intravenously once each on day 1, day 8, day 15, and day 22, and then repeated in cycles; (2) prednisone 1mg/kg, orally every day for a total of 25 days, then once every other day; (3) L-asparaginase 100001U/m2, administered intramuscularly once each on day 1, day 8, day 15, and day 22; (4) if there is improvement and granulocytes >3000/ul, after day 22 stop L-asparaginase treatment and switch to oral cyclophosphamide, 250mg/m2, also administered on day 1, day 8, day 15, and day 22. Five to seven days after medication, check the granulocytes; granulocytes<1000个/ul时，环磷酰胺量应减少25%。

3. For treating feline lymphosarcoma, the following can also be used: (1) vincristine sulfate, for usage see 2(1); (2) prednisone, for cats 2mg/kg per day, for usage see 2(2); (3) cyclophosphamide, for cats 300mg/m2; if granulocytopenia occurs, its dosage should be reduced.