Canine and Feline Lymphosarcoma

1 Understanding Lymphosarcoma

Lymphosarcoma (also called lymphoma) is a malignant tumor that arises from the lymph nodes or other lymphoid tissue. Both cats and dogs can develop it, though it is seen more often in dogs, typically those aged four years and older.

The disease is classified into three main forms: multicentric (involving peripheral lymph nodes), alimentary (involving the digestive tract), and thymic (involving the chest). In cats, the alimentary and thymic forms are the most common, while the multicentric form is comparatively rare.

2 Clinical Signs

In the multicentric form, the main signs are lethargy, reduced appetite, and weight loss, along with symmetric, painless swelling of the superficial lymph nodes. Fluid accumulation may cause swelling of the face and limbs, and the liver, spleen, or abdomen can enlarge.

The alimentary form causes severe diarrhea or dysentery, often with anorexia and vomiting. On abdominal palpation, sausage-shaped tumor masses may be felt, though in some cases the lesions are more widely scattered.

Thymic lymphosarcoma tends to appear in young dogs, usually under three years of age. Affected dogs may die suddenly with no warning, or after a brief period of anorexia and labored breathing. On an X-ray, a large radiopaque mass can be seen occupying the front half of the chest cavity.

3 Prognosis & Veterinary Guidance

Without treatment, lymphosarcoma is usually fatal within 4–6 weeks. With active treatment, however, survival can be extended to 6–24 months, so a diagnosis should not lead to immediate euthanasia.

Because these cases are relatively uncommon, treatment costs can be high. For pets showing reduced appetite and weight loss, an oral IgG (egg-yolk antibody) supplement can help restore appetite and support immune function—given once daily, one dose per day, for five consecutive days.

4 Treatment Protocol

Many cats pass away within weeks of diagnosis, so treatment is typically initiated promptly. A common chemotherapy protocol includes:

1. Cyclophosphamide: 2 mg/kg, orally, every other day or once daily.

2. Vincristine: 0.02–0.05 mg/kg, intravenously, every 7–10 days.

3. Prednisone: 2 mg/kg orally, with the weekly dose reduced by 0.5 mg/kg down to 0.5 mg/kg, then discontinued.

4. L-asparaginase: dogs 400 IU/kg by intramuscular or subcutaneous injection, 1–2 times per week; cats 400 IU/kg by intramuscular, subcutaneous, or intraperitoneal injection.

5. Doxorubicin: 30 mg/kg intravenously, once every 3 weeks.

6. Mitoxantrone: 6 mg/kg intravenously, once every 3 weeks.