Canine and Feline Lymphosarcoma (Lymphoma)

1 Symptoms

Lymphosarcoma is a malignant tumor of lymphocytes arising in lymph nodes or other lymphoid tissue. It occurs in both dogs and cats, though it is not common, and tends to appear in dogs from about 4 years of age upward.

The multicentric form shows lethargy, reduced appetite, and weight loss, with symmetrical, painless enlargement of the peripheral lymph nodes, swelling of the face and limbs, and enlargement of the liver and spleen with fluid buildup in the abdomen. In cats the alimentary and thymic forms are most common, while the multicentric form is less frequent.

The alimentary form causes severe diarrhea or dysentery, often with anorexia and vomiting; a sausage-shaped tumor mass may be felt on abdominal examination. Thymic lymphosarcoma tends to appear in young dogs, usually under 3 years, and affected pets may die suddenly after a brief period of poor appetite and breathing difficulty. Chest X-rays show a large opaque mass occupying the front of the chest.

2 Causes and Transmission

The cause is not fully known. It is not considered contagious in the usual sense, although retroviruses are implicated in some feline cases. It does not spread directly between pets like an infection.

3 Diagnosis

Diagnosis uses fine-needle aspiration or biopsy of the affected nodes or organs, blood work, and imaging such as X-ray or ultrasound to stage the disease. Many cats die within weeks of diagnosis without treatment.

4 Treatment

Lymphosarcoma is generally not curable, but treatment can extend life from a typical 4 to 6 weeks when untreated to about 6 to 24 months with therapy. A veterinary-directed chemotherapy protocol using combinations of agents such as alkylating drugs, vinca alkaloids, corticosteroids, and anthracyclines is used; the exact drugs and schedule are individualized for each pet.

Nutritional support, including appetite stimulants and immune-supportive supplements, helps maintain condition during treatment.

5 Prevention and Home Care

There is no reliable prevention. Watch for lumps, weight loss, appetite changes, or digestive signs, and seek veterinary care early.

During treatment, provide good nutrition, reduce stress, and follow your veterinarian’s monitoring plan. Discuss quality-of-life decisions openly with your clinician so care stays aligned with your pet’s well-being.